Vallis (planetary geology)

Vallis or valles (plural "valles" ) is the Latin word for "valley". It is used in planetary geology to name landform features on other planets.
Scientists used "vallis" for old river valleys they discovered when they sent the first probes to Mars. The Viking Orbiters caused a revolution in our ideas about water on Mars; finding huge river valleys in many areas. Space craft cameras showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers. Some valles on Mars (Mangala Vallis, Athabasca Vallis, Granicus Vallis, and Tinjar Valles) clearly begin at graben. On the other hand, some of the large outflow channels begin in rubble-filled low areas, called chaos or chaotic terrain. It has been suggested that massive amounts of water were trapped under pressure beneath a thick cryosphere (layer of frozen ground), then the water was suddenly released, perhaps when the cryosphere was broken by a fault.
Nirgal Vallis and sapping.
Nirgal Vallis is one of the longest valley networks on Mars. It is so large that it is found on more than one quadrangle. Scientists are not sure about how all the ancient river valleys were formed. There is evidence that instead of rain or snow, the water that formed the valleys originated underground. One mechanism that has been advanced is sapping. In sapping, the ground just gives away as water comes out. Sapping is common in some desert areas in America's Southwest. Sapping forms alcoves and stubby tributaries. These features are visible in the picture from the Coprates quadrangle of Nigal Vallis taken with Mars Odyssey's THEMIS.
Kasei Valles.
One of the most significant features of the Lunae Palus region, Kasei Valles is one of the largest outflow channels on Mars. Like other outflow channels, it was carved by liquid water, probably during gigantic floods.
Kasei is about long. Some sections of Kasei Valles are wide. It begins in Echus Chasma, near Valles Marineris, and empties into Chryse Planitia, not far from where Viking 1 landed. Sacra Mensa, a large tableland divides Kasei into northern and southern channels.
Scientists suggest it was formed by several episodes of flooding and maybe by some glacial activity.
Lineated Floor Deposits.
The floors of some channels have features called lineated floor deposits. They are ridged and grooved materials that seem to deflect around obstacles. Scientists believe they are ice-rich. Some glaciers on the Earth show such features. Lineated floor deposits may be related to lobate debris aprons, which have been proven to contain large amounts of ice. Reull Vallis, as pictured below, displays these deposits.
Origin of Dao Vallis.
Dao Vallis begins near a large volcano, called Hadriaca Patera, so it is thought to have received water when hot magma melted huge amounts of ice in the frozen ground. The partially circular depressions on the left side of the channel in the image below suggests that groundwater sapping also contributed water.


Cascaden Ridge Formation

The Cascaden Ridge Formation is a geologic formation in Alaska. It preserves fossils dating back to the Devonian period.


Eisenberg Formation

The Eisenberg Formation is a geologic formation in Austria. It preserves fossils dating back to the Devonian period.


Esbataottine Formation

The Esbataottine Formation is a geologic formation in Northwest Territories. It preserves fossils dating back to the Ordovician period.


Alston Formation

The Alston Formation is a geologic formation in England. It preserves fossils dating back to the Viséan to Serpukhovian (Asbian, Brigantian and Pendleian in British straigraphy) stages of the Carboniferous period.


Marcellina Mountain

Marcellina Mountain is a prominent mountain summit in the West Elk Mountains range of the Rocky Mountains of North America. The peak is located in the Raggeds Wilderness of Gunnison National Forest, west by north (bearing 287°) of the Town of Crested Butte in Gunnison County, Colorado, United States.


Melanocratic rock

A melanocratic rock contains at least 60% dark and heavy ferro-magnesium minerals.<ref name="http://thesciencedictionary.org/melanocratic/">What is Melanocratic? definition of Melanocratic (Science Dictionary): dark and heavy ferro-magnesian mineral, accessdate: March 10, 2017</ref>


Calschistes de la bande ouest du Morvan

The Calschistes de la bande ouest du Morvan is a geologic formation in France. It preserves fossils dating back to the Carboniferous period.


Woolhope Limestone

The Woolhope Limestone is a geologic formation in Wales. It preserves fossils dating back to the Silurian period.


Essexite

Essexite (), also called nepheline monzogabbro (), is a dark gray or black holocrystalline plutonic igneous rock. Its name is derived from the type locality in Essex County, Massachusetts, in the United States.
Modern petrology identifies rocks according to mineralogical criteria. Utilising the IUGS QAPF diagram of Streckeisen (1974) "essexite" is more formally known as nepheline monzodiorite or nepheline monzogabbro depending on the ratio of orthoclase to plagioclase and the abundance of nepheline.
Petrology.
In order to produce a magma composition suitable for forming essexite the partial melting of the source rocks must be restricted, generally to less than 10% partial melting. This favors producing a melt rich in large-ion lithophile elements (LILE) such as K, Ba, Rb, Cs, Sr.
The source melts of essexites contain more aluminium and alkali ions than available silica tetrahedra, which is why essexites crystallise nepheline instead of plagioclase. Higher than normal potassium favors the production of orthoclase, which is usually absent from most mafic igneous rocks.
Mineralogy.
Essexite can be considered as an alkali gabbro or monzodiorite primarily composed of nepheline, plagioclase, with lesser amounts of alkali feldspar, with mafic minerals composed of any of the following; titanium augite (pyroxene), hornblende and biotite.
Trace mineralogy may include magnetite, ilmenite and accessory olivine (<5%).
Essexite grades into a nepheline monzogabbro with a decrease in potassium feldspar and an increase in the feldspathoid minerals.
Geochemistry.
Essexite is an alkaline igneous rock equivalent to an alkaline basalt. The presence of nepheline, a feldspathoid mineral, indicates that essexites are silica undersaturated. The presence of orthoclase indicates that it contains sufficient potassium to favor production of orthoclase over microcline or potassic oligoclase.
Essexites are generally rich in aluminium, alkalis (sodium and calcium), potassium (>3% K2O), LILE-enriched (strontium, caesium and barium), as compared to tholeiitic basalts and gabbros.


Oberhofer Formation

The Oberhofer Formation is a geologic formation in Germany. It preserves fossils dating back to the Permian period.


Sar-i Sang

Sar-i Sang (or Sar-e Sang) is a settlement in the Kuran Wa Munjan District of Badakhshan Province, Afghanistan, famous for its ancient lapis lazuli mines producing the world's finest lapis.
Lapis lazuli mines.
The Sar-i Sang lapis lazuli mine probably dates from proto-historic times. It consists of one old disused shaft and two new shafts. This was the main source of lapis lazuli in the ancient world, with lapis from here occurring in such famous archaeological discoveries as the Royal Treasure of Ur and the Tomb of Tutankhamun.


Dorsal de Huincul


Kugururok Formation

The Kugururok Formation is a geologic formation in Alaska. It preserves fossils dating back to the Devonian period.


McColley Canyon Formation

The McColley Canyon Formation is a geologic formation in Nevada. It preserves fossils dating back to the Devonian period.


Cabot Head Shale

The Cabot Head Shale is a geologic formation in Michigan. It preserves fossils dating back to the Silurian period.


Serpentinite

Serpentinite is a rock composed of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Minerals in this group, which are rich in magnesium and water, light to dark green, greasy looking and slippery feeling, are formed by serpentinization, a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle. The mineral alteration is particularly important at the sea floor at tectonic plate boundaries.
Formation and petrology.
Serpentinization is a geological low-temperature metamorphic process involving heat and water in which low-silica mafic and ultramafic rocks are oxidized (anaerobic oxidation of by the protons of water leading to the formation of ) and hydrolyzed with water into serpentinite. Peridotite, including dunite, at and near the seafloor and in mountain belts is converted to serpentine, brucite, magnetite, and other minerals – some rare, such as awaruite (), and even native iron. In the process large amounts of water are absorbed into the rock increasing the volume, reducing the density and destroying the structure.
The density changes from with a concurrent volume increase on the order of 30-40%. The reaction is highly exothermic and rock temperatures can be raised by about , providing an energy source for formation of non-volcanic hydrothermal vents. The magnetite-forming chemical reactions produce hydrogen gas under anaerobic conditions prevailing deep in the mantle, far from the Earth's atmosphere. Carbonates and sulfates are subsequently reduced by hydrogen and form methane and hydrogen sulfide. The hydrogen, methane, and hydrogen sulfide provide energy sources for deep sea chemotroph microorganisms.
Formation of serpentinite.
Serpentinite can form from olivine via several reactions. Olivine is a solid solution of forsterite, the magnesium-endmember, and fayalite, the iron-endmember.
Reaction 1c describes the hydration of olivine to yield serpentine and (brucite). Serpentine is stable at high pH in the presence of brucite like calcium silicate hydrate, (C-S-H) phases formed along with portlandite () in hardened Portland cement paste after the hydration of belite (), the artificial calcium equivalent of forsterite.
Analogy of reaction 1c with belite hydration in ordinary Portland cement:
After reaction, the poorly soluble reaction products (aqueous silica or dissolved magnesium ions) can be transported in solution out of the serpentinized zone by diffusion or advection.
A similar suite of reactions involves pyroxene-group minerals, though less readily and with complication of the additional end-products due to the wider compositions of pyroxene and pyroxene-olivine mixes. Talc and magnesian chlorite are possible products, together with the serpentine minerals antigorite, lizardite, and chrysotile. The final mineralogy depends both on rock and fluid compositions, temperature, and pressure. Antigorite forms in reactions at temperatures that can exceed during metamorphism, and it is the serpentine group mineral stable at the highest temperatures. Lizardite and chrysotile can form at low temperatures very near the Earth's surface. Fluids involved in serpentinite formation commonly are highly reactive and may transport calcium and other elements into surrounding rocks; fluid reaction with these rocks may create metasomatic reaction zones enriched in calcium and called rodingites.
In the presence of carbon dioxide, however, serpentinitization may form either magnesite () or generate methane (). It is thought that some hydrocarbon gases may be produced by serpentinite reactions within the oceanic crust.
Or, in balanced form:
Reaction 2a is favored if the serpentinite is Mg-poor or if there is not enough carbon dioxide to promote talc formation. Reaction 2b is favored in highly magnesian compositions and low partial pressure of carbon dioxide.
The degree to which a mass of ultramafic rock undergoes serpentinisation depends on the starting rock composition and on whether or not fluids transport calcium, magnesium and other elements away during the process. If an olivine composition contains sufficient fayalite, then olivine plus water can completely metamorphose to serpentine and magnetite in a closed system. In most ultramafic rocks formed in the Earth's mantle, however, the olivine is about 90% forsterite endmember, and for that olivine to react completely to serpentine, magnesium must be transported out of the reacting volume.
Serpentinitization of a mass of peridotite usually destroys all previous textural evidence because the serpentine minerals are weak and behave in a very ductile fashion. However, some masses of serpentinite are less severely deformed, as evidenced by the apparent preservation of textures inherited from the peridotite, and the serpentinites may have behaved in a rigid fashion.
Hydrogen production by anaerobic oxidation of fayalite ferrous ions.
Serpentine is the product of the reaction between water and fayalite's ferrous () ions. The process is of interest because it generates hydrogen gas:
The reaction can be viewed simplistically as follows:
This reaction resembles the Schikorr reaction observed in the anaerobic oxidation of the ferrous hydroxide in contact with water.
Extraterrestrial production of methane by serpentinization.
The presence of traces of methane in the atmosphere of Mars has been hypothesized to be a possible evidence for life on Mars if methane was produced by bacterial activity. Serpentinization has been proposed as an alternative non-biological source for the observed methane traces.
Using data from the Cassini probe flybys obtained in 2010–12, scientists were able to confirm that Saturn's moon Enceladus likely has a liquid water ocean beneath its frozen surface. A model suggests that the ocean on Enceladus has an alkaline pH of 11–12. The high pH is interpreted to be a key consequence of serpentinization of chondritic rock, that leads to the generation of , a geochemical source of energy that can support both abiotic and biological synthesis of organic molecules.
Impact on agriculture.
Soil cover over serpentinite bedrock tends to be thin or absent. Soil with serpentine is poor in calcium and other major plant nutrients, but rich in elements toxic to plants such as chromium and nickel.
Uses.
Decorative stone in architecture and art.
Grades of serpentinite higher in calcite, along with the verd antique (breccia form of serpentinite), have historically been used as decorative stones for their marble-like qualities. College Hall at the University of Pennsylvania, for example, is constructed out of serpentine. Popular sources in Europe before contact with the Americas were the mountainous Piedmont region of Italy and Larissa, Greece.
Serpentinites are used in many ways in the arts and crafts. For example, the rock has been turned in Zöblitz in Saxony for several hundred years.
Carvingstone tools, oil lamp-known as the Qulliq and Inuit sculpture.
Inuit and indigenous people of the Arctic areas and less so of southern areas used the carved bowl shaped serpentinite Qulliq or Kudlik lamp with wick, to burn oil or fat to heat, make light and cook with. Inuit made tools and more recently carvings of animals for commerce.
Swiss ovenstone.
A variety of chlorite talc schist associated with Alpine serpentinite is found in Val d'Anniviers, Switzerland and was used for making "ovenstones" (), a carved stone base beneath a cast iron stove.
Neutron shield in nuclear reactors.
Serpentinite has a significant amount of bound water, hence it contains abundant hydrogen atoms able to slow down neutrons by elastic collision (neutron thermalization process). Because of this serpentinite can be used as dry filler inside steel jackets in some designs of nuclear reactors. For example, in RBMK series, as at Chernobyl, it was used for top radiation shielding to protect operators from escaping neutrons. Serpentine can also be added as aggregate to special concrete used in nuclear reactor shielding to increase the concrete density () and its neutron capture cross section.
Cultural references.
It is the state rock of California, USA and the California Legislature specified that serpentine was "the official State Rock and lithologic emblem." In 2010, a bill was introduced which would have removed serpentine's special status as state rock due to it potentially containing chrysotile asbestos. The bill met with resistance from some California geologists, who noted that the chrysotile present is not hazardous unless it is mobilized in the air as dust.


Nocona Formation

The Nocona Formation is a geologic formation in Texas. It preserves fossils dating back to the Permian period.


Murdock Station Formation

The Murdock Station Formation is a geologic formation in Florida. It preserves fossils dating back to the Neogene period.


Wades Lane Formation

The Wades Lane Formation is a geologic formation in New Brunswick. It preserves fossils dating back to the Cambrian period.


McKay Group

The McKay Group is a geologic group in British Columbia. It preserves fossils dating back to the Cambrian period.


Kincaid Formation

The Kincaid Formation is a geologic formation in Texas. It preserves fossils dating back to the Paleogene period.


Louis J. Lanzerotti

Louis John Lanzerotti (born April 16, 1938) is a Distinguished Research Professor of physics in the "Center for Solar-Terrestrial Research" at New Jersey Institute of Technology (NJIT) in Newark, New Jersey.
His principal research interests have included space plasmas, geophysics, and engineering problems related to the impacts of atmospheric and space processes and the space environment on space and terrestrial technologies.
Early life.
Louis J. Lanzerotti was born and grew up in Carlinville, Illinois. He earned a BS in Engineering Physics in 1960 from University of Illinois. He obtained his MS and PhD degrees, both in Physics, and both from Harvard University in 1963 and 1965 respectively.
Career.
After serving as a postdoctoral fellow at Harvard University, he joined AT&T's Bell Laboratories in 1965 to engage in engineering and scientific research on Earth’s radiation belts, the existence of which was confirmed a few years earlier by James Van Allen. AT&T’s Telstar satellites had recently been launched, providing Lanzerotti and his colleagues with data for analyzing and interpreting the radiation belts and their effects of radiation on space systems. This marked the beginning of Lanzerotti’s leadership in the field now called “space weather.” Lanzerotti's work led to him being named a "Distinguished Member of Technical Staff" at Lucent Technologies.
Lanzerotti worked with multiple satellite programs and space missions, including the ATS-1 and ATS-3 communications satellites, the interplanetary IMP 4 and IMP 5 explorer missions, the Voyager missions to the outer planets and interstellar medium, the ACE solar wind mission, and the Cassini mission to Saturn. Furthermore, Lanzerotti has been awarded many NSF research grants including as the principal investigator for instruments aboard the Ulysses mission over the poles of the Sun, the Galileo mission to Jupiter, and more recently the Van Allen Probes, launched in 2012 to study Earth's radiation belts. He retired in 2002 and remained a consultant to Alcatel-Lucent through 2008. In 2002, he was appointed a Distinguished Research Professor of Physics in the Center for Solar-Terrestrial Research at the New Jersey Institute of Technology in Newark, New Jersey. He has also served as an adjunct professor of electrical engineering at the University of Florida and as a Regents' lecture at UCLA. He is currently "Distinguished Research Professor of Physics" at the New Jersey Institute of Technology.
Much of his research has involved close collaborations with telecommunications service providers on commercial satellite and long-haul (principally transoceanic) cables. His research has also involved geomagnetism, solid earth geophysics, and some oceanography. This research has been applied to design and operations of systems associated with spacecraft and cable operations. Lanzerotti has served as principal investigator or co-investigator on several United States NASA interplanetary and planetary missions including ATS-1&3, IMP-4&5, Voyager 1&2, Ulysses, Galileo Orbiter and Entry Probe, ACE, and Cassini. Currently, he is a Principal Investigator with instruments on each of the two spacecraft in the NASA Van Allen Probes mission launched August 2012. He has also conducted geophysical research in the Antarctic and the Arctic beginning in the 1970s, directed largely toward understanding of Earth's upper atmosphere and space environments.
Lanzerotti has served as an associate editor for the Journal of Geophysical Research and is the founding editor of the online journal Space Weather.
In recognition of his career as a research scientist and engineer, Lanzerotti was appointed by US President George W. Bush to the National Science Board, the 24-member governing body of the National Science Foundation (NSF) and served a 6-year term from 2004 to 2010. He served on the board as a "Board Consultant" from May 2010 until April 2012. Lanzerotti also led a 12-member panel organized by the National Research Council (NRC) of the National Academies to identify possible causes of unintended acceleration in vehicles in the aftermath of Toyota's large automobile recalls.
Lanzerotti has authored or co-authored of more than 500 refereed publications, contributing to research that includes studies of space plasmas and geophysics, and engineering problems related to the impact of atmospheric and space processes (a.k.a. "space weather") on terrestrial and spaceborne technologies. Lanzerotti co-authored a book on radiation belt physics and has co-edited four books. He has eight patents issued or filed.
In addition to his career in science, Lanzerotti served in the Harding Township, New Jersey local government. In the 1980s he was elected to three 3-year terms on his Harding Township, N. J., school board, with 6 years as chair of its curriculum committee and 6 years as vice president. Since 1993 he has served six elected terms on the township governing body, including 3 years as mayor.
Service activities.
Member or Chair ~ 40 committees of NASEM (including examples below) 1979-


Haragan Formation

The Haragan Formation is a geologic formation in Oklahoma. It preserves fossils dating back to the Devonian period.


Brilliant (diamond cut)

A brilliant is a diamond or other gemstone cut in a particular form with numerous facets so as to have exceptional brilliance. The shape resembles that of a cone and provides maximized light return through the top of the diamond.
Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight; rarely is it less than 50%. The round brilliant cut is preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals such as macles are more likely to be cut in a "fancy cut"—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.
Facet proportions and names.
The original round brilliant-cut was developed by Marcel Tolkowsky in 1919. The modern round brilliant consists of 58 facets (or 57 if the culet is excluded), ordinarily today cut in two pyramids placed base to base: 33 on the "crown" (the top half above the middle or "girdle" of the stone), truncated comparatively near its base by the table, and 25 on the "pavilion" (the lower half below the girdle), which has only the apex cut off to form the culet, around which 8 extra facets are sometimes added. In recent decades, most girdles are faceted. Many girdles have 32, 64, 80, or 96 facets; these facets are not counted in the total. While the facet count is standard, the actual proportions (crown height and angle, pavilion depth, etc.) are not universally agreed upon. Some gem cutters refer to an American brilliant cut or a Scandinavian brilliant cut. Quoting Green et al. 2001:
Figures 1 and 2 show the facets of a round brilliant diamond.
Figure 1 assumes that the "thick part of the girdle" is the same thickness at all 16 "thick parts". It does not consider the effects of indexed upper girdle facets.
Figure 2 is adapted from Figure 37 of Marcel Tolkowsky's Diamond Design, which was originally published in 1919. Since 1919, the lower girdle facets have become longer. As a result, the pavilion main facets have become narrower.
Cut grading.
The relationship between the crown angle and the pavilion angle has the greatest effect on the look of the diamond. A slightly steep pavilion angle can sometimes be complemented by a shallower crown angle, and "vice versa".
Other proportions also affect the look of the diamond:
Several groups have developed diamond cut grading standards. They all disagree somewhat on which proportions make the best cut. There are certain proportions that are considered best by two or more groups however.
The distance from the viewer's eye to the diamond is important.
The 2005 AGS cut standards are based on a distance of 25 centimeters (about 10 inches).
The 2004 HCA cut standards are based on a distance of 40 centimeters (about 16 inches).
Polish and symmetry are two important aspects of the cut. The polish grade describes the smoothness of the diamond's facets, and the symmetry grade refers to alignment of the facets. With poor polish, the surface of a facet can be dulled, and may create blurred or dulled sparkle. It may constantly look like it needs to be cleaned. With poor symmetry, light can be misdirected as it enters and exits the diamond.
Hearts and arrows phenomenon.
A diamond that has the top facet or "table facet" exactly perpendicular to the bottom of the diamond or "pavilion" and has its other facets precisely aligned with excellent symmetry, may show patterns that look like arrows from the top and hearts from the bottom. Generally it will need to be viewed loose under a gemscope to see the pattern very well. Although the hearts and arrows property is indicative of a top-tier cut, it does not always mean the diamond will be the most brilliant. Optimal facet placement is the key to brilliance and more important than facet patterning. Not all ideal round cuts will have the hearts and arrows effect either.


Dispersal index

Dispersal index is a parameter in volcanology. The dispersal index formula_1 was defined by George P. L. Walker in 1973 as the surface area covered by an ash or tephra fall, where the thickness is equal or more than 1/100 of the thickness of the fall at the vent. An eruption with a low dispersal index leaves most of its products close to the vent, forming a cone; an eruption with a high dispersal index forms thinner sheet-like deposits which extends to larger distances from the vent. A dispersal index of or more of coarse pumice is one proposed definition of a Plinian eruption. Likewise, a dispersal index of has been proposed as a cutoff for an ultraplinian eruption. The definition of 1/100 of the near-vent thickness was partially dictated by the fact that most tephra deposits are not well preserved at larger distances.
Originally, the dispersal index was considered a function of the height of the eruption column. Later, a role for the size of the tephra and ash particles was identified, with coarser fall deposits covering smaller surfaces than finer deposits generated by a column of the same height. For example, a deposit with a dispersal index of can be formed by a column with heights of . Thus, Walker's idea of the column height alone separating a cone forming eruption and an eruption generating a sheet-like deposit was later considered oversimplified. An additional complicating factor is that fine particles are prone to aggregating and thus falling out more quickly from the column. Further problems arise when the maximum thickness has to be determined.
The height of the eruption column, the presence and behaviour of water, the speed and direction of the wind as well as the sizes of the various tephra particles influence the fallout patterns of an ash cloud.
The dispersal index for volcanic eruptions ranges from < and . A number of basaltic phreatomagmatic deposits, frequently associated with tuff rings, have a dispersal index of less than .
A related measure is the thickness half-distance formula_2, which defines the distance over which the thickness of a deposit halves. These values are related with each other over formula_3 for circular deposits.


Macaronichnus

Macaronichnus is an ichnogenus of trace fossil.
The environmental preferences of "Macaronichnus" are high-energy foreshores and shallow shorefaces. "Macaronichnus" is an indicator of temperate to cold waters.


Desert Peak Formation

The Desert Peak Formation is a geologic formation in Nevada. It preserves fossils dating back to the Neogene period.


Ross Brook Formation

The Ross Brook Formation is a geologic formation in Nova Scotia. It preserves fossils dating back to the Silurian period.


Manebacher Formation

The Manebacher Formation is a geologic formation in Germany. It preserves fossils dating back to the Permian period.


Iberg Reef Formation

The Iberg Reef Formation is a geologic formation in Germany. It preserves fossils dating back to the Devonian period.


Waterhead Group

The Waterhead Group is a geologic group in Scotland. It preserves fossils dating back to the Silurian period.


Transpression

In geology, transpression is a type of strike-slip deformation that deviates from simple shear because of a simultaneous component of shortening perpendicular to the fault plane. This movement ends up resulting in oblique shear. It is generally very unlikely that a deforming body will experience "pure" shortening or "pure" strike-slip. The relative amounts of shortening and strike-slip can be expressed in the convergence angle alpha which ranges from zero (ideal strike-slip) to 90 degrees (ideal convergence). During shortening, unless material is lost, transpression produces vertical thickening in the crust. Transpression that occurs on a regional scale along plate boundaries is characterized by oblique convergence. More locally, transpression occurs within restraining bends in strike-slip fault zones.
Transpressional structures.
Transpressional shear zones are characterized by an association of structures that suggest zone-normal shortening and zone-parallel shearing. Commonly developed features include transposition foliations, lineations, stylolites, folds, and reverse faults. Pure shear-dominated transpression usually gives steep lineations, while simple shear-dominated transpression favors horizontal lineations. It is also common for non-vertical transpressional zones to have a significant component of shearing parallel to the dipline of the zone boundary. In these zones, the lineations are between horizontal and vertical. The complete geometry presented by all structural elements in the zone is used to constrain the actual boundary displacements. .
Restraining bend.
A fault bend, or fault stepover, forms when individual segments of the fault overlap and link together. The type of structures which form along the strike-slip fault depend on the sense of slip relative to the sense of stepping. When a sinistral fault steps to the right or a dextral fault steps to the left, a restraining bend is formed. These are areas of positive relief (topographic uplift), crustal shortening, and exhumation of crystalline basement. As seen in deeply eroded outcrop exposures or from subsurface geophysical surveys, restraining bends commonly define positive flower structures. In plan view we see them form contractional strike-slip duplexes, subparallel reverse or oblique-slip contractional faults that are bounded by two strike-slip segments. Restraining bends are widespread on the Earth's surface, from sub-outcrop-scale examples to large scale mountain ranges. They have been theorized to occur on extraterrestrial bodies, like Jupiter's icy moon Europa and on Venus.


Nilokeras Scopulus

Nilokeras Scopulus is a long escarpment (cliff) in the northern hemisphere of the planet Mars. It is located along the southeastern boundary of the Tempe Terra plateau and forms the northern valley wall (wallrock boundary) of the downstream portion of the immense Kasei Valles outflow channel system. The escarpment is 765 km long and ranges from 1 to a little over 2 km (3300–6600 ft) in height.
For most of its length, Nilokeras Scopulus lies between lat. 31° and 32° N. It trends west-east, extending from approximately long. 297° to 309° E. The escarpment curves northward at the eastern edge of Tempe Terra where the northern segment of Kasei Valles debouches into Chryse and southwestern Acidalia Planitiae.
Name origin.
Nilokeras, which is Greek for "horn of the Nile," was the name given by astronomer E. M. Antoniadi in 1930 to a telescopic albedo feature and canal centered at lat. 30° N., long. 55° W. (See List of Martian canals.) Scopulus is a descriptor term used in planetary geology for an irregular escarpment or cliff. The International Astronomical Union (IAU) formally adopted the name Nilokeras Scopulus in 1976. Scopulus is the Latin term for "crag" or cliff.
Geology.
In geomorphology, an escarpment (usually shortened to scarp) is any steep, abrupt slope or cliff along the margin of a plateau, terrace, or other topographic bench. A scarp may be formed by tectonic, erosional, or depositional processes. The term carries no implication of geologic origin.
Nilokeras Scopulus likely formed from a combination of faulting and erosion from flood waters that formed Kasei Valles. Recent geologic mapping of the Kasei Valles region indicates that the west-to-east flow of the Kasei Valles floods followed the existing structural trend of rift valleys in southern Tempe Terra. Thus, the proto-Nilokeras Scopulus was probably an east-west oriented fault scarp or fracture zone (or zone of weakness) that was eroded and further downcut by at least one (and possibly two) episodes of early catastrophic flooding from the northern Tharsis region. (See outflow channels.) These floods occurred in Hesperian time between about 3.6 and 3.4 billion years ago (Gya).
After initial flooding, the northern Kasei valley was covered by extensive late Hesperian-aged basaltic lava flows from Tharsis. Two final episode of flooding from the Echus Chasma region to the south occurred in Kasei Valles during Amazonian times (<1.8 Gya). The later floods carved the channels south of Nilokeras Scopulus and may not have strongly influenced development of the scarp.
During the course of its history, Nilokeras Scopulus has been subjected to glacial/periglacial processes and modified by groundwater sapping, slumping, collapse, and other mass wasting processes. Rocks making up the scarp face are Noachian or Early Hesperian in age (>3.6 Gya). They probably consist of ancient impact breccias and volcanic materials. Layered bedrock is visible at the top of the escarpment in some medium and high resolution spacecraft images, but the scarp face is largely covered by talus aprons and dust.


Polarcus

Polarcus Limited is an offshore geophysical company operating a fleet of seismic research vessels worldwide.
The company describes itself as having a strong environmental focus that aims to decrease emissions to both sea and air. Polarcus vessels have received high energy efficiency and environmental performance ratings.
Polarcus provides worldwide seismic data acquisition services and Multi-Client library data as well as seismic data imaging to help energy companies find oil and gas reserves offshore.
The company was founded in 2008 in Dubai, UAE.
Shares.
Polarcus listed its shares on the Oslo Stock Exchange OTC list in 2008, and has since 2009 been trading on the Oslo Stock Exchange OSE list, under the ticker PLCS.


Feng Xiating

Feng Xiating (; born September 1964) is a Chinese petrologist who is a professor and vice-president of Northeastern University (China), and currently president of Chinese Society for Rock Mechanics & Engineering (CSRME). He was president of the International Society for Rock Mechanics (ISRM) from 2011 to 2015.
Biography.
Feng was born into a family of farming background in September 1964 in the town of , Qianshan, Anhui. He received his bachelor's degree and doctor's degree from Northeastern University (China) in 1986 and 1992, respectively. After graduation, the university gave him accelerated promotion to associate professor and to full professor three years later.
He successively worked as a visiting research fellow at the Institute of Resources and Environment Technology in Japan (September 1995–March 1996), senior research officer at the University of the Witwatersrand (May 1996–November 1996), special researcher at the Japan International Industrial Technology Research Institute (December 1996–November 1997), and academy visitor at the Imperial College London (January 2001–March 2001). In June 2001 he became deputy of the Institute of Rock and Soil Mechanics, Chinese Academy of Sciences (CAS), and two years later he rose to become director. In August 2017 he was recalled to the Northeastern University and appointed vice-president.


Disconformity


Ladera Sandstone

The Ladera Sandstone is a geologic formation in California. It preserves fossils dating to the Neogene period.


Contourite

A contourite is a sedimentary deposit commonly formed on continental rise to lower slope settings, although they may occur anywhere that is below storm wave base. Countourites are produced by thermohaline-induced deepwater bottom currents and may be influenced by wind or tidal forces. The geomorphology of contourite deposits is mainly influenced by the deepwater bottom-current velocity, sediment supply, and seafloor topography.
Definition.
The definition of the term contourite has varied throughout the decades. Originally, Heezen "et al." (1966) defined the concept, without using the actual word, as a sedimentary deposit on the continental rise derived from thermohaline-induced geostrophic bottom-currents that flow parallel to bathymetric contours. They did this to emphasize the difference between these deposits and turbidites in order to explain the ubiquitous smoothness and lack of irregularities of the continental rise in the Blake-Bahama Basin. Before this, it was thought that only turbidity flows were capable of depositing and reworking sediment at depths greater than the continental slope. Hollister and Heezen (1972) adopted the name contourite for these deposits and provided a list of characteristics that described their sediments. Faugères and Stow (1993) note that as research on the subject developed, the term contourite was used to describe various forms of sedimentary deposits from bottom-currents including those at much shallower depths and even in lacustrine settings. They suggested going back to the original definition of a contourite, that is for deposits at depths greater than 500 m derived from stable thermohaline-induced geostrophic bottom-currents (i.e. deepwater bottom-currents), in order to avoid using the same name when describing sedimentary deposits formed by different processes. They also suggest the umbrella term bottom-current deposit, which includes contourites and deposits generated by other bottom-currents.
Flow conditions.
Thermohaline circulation is the principal driving force of deepwater bottom-currents. The term refers to the movement of water over large distances as a consequence of global oceanic density gradients. This circulation commonly travels at velocities between 2 – 20 cm/s. Note that at this velocity range, considering the general shape of the Shields diagram still holds in these conditions, a flow will only be able to continue transporting finer sediment that is already in suspension but will not be able to erode the same sized sediment once it is deposited. However, flow velocity may be intensified as a consequence of the Coriolis force driving currents west against continental margins or as current squeezes between two ridges.
Periodically, velocities may increase dramatically or even reverse due to atmospheric storms raising the local surface eddy kinetic energy, which gets partially transmitted down to abyssal depths in episodes called benthic storms. These velocities may reach magnitudes well above 40 cm/s and vary significantly depending on the specific location. At the lower continental rise, south of Halifax, Nova Scotia, and at the lower slope around the Faeroe Islands these velocities may reach up to 73 cm/s and 75 cm/s, respectively. Bottom-current flow velocities have been measured as high as 300 cm/s in the Strait of Gibraltar. These benthic storms occur only 5 to 10 times per year and usually last between 3 and 5 days, but that is enough to heavily erode benthic sediment and keep the finer grains in suspension even after flow velocities return to normal and the bedload has been deposited. During benthic storms, the eroded sediment may be transported over thousands of kilometers and deposited rather quickly (i.e. ~1.5 cm/month) once the storm wanes. However, the net sedimentation rate over thousands of years may be much smaller (i.e. ~5.5 cm/year) due to the intense periods of erosion during benthic storms.
Sediment supply.
Erosion of the seafloor contributes to the growth of a deepwater nepheloid layer. This layer plays a key role in supplying the sediment for the deposition of contourites under appropriate flow conditions.
Terrigenous sediment supply to the deepwater bottom-currents and to the nepheloid layer primarily depends on climate and tectonics in the continental environment. The rate of tectonic uplift is directly related to the amount of sediment available and variations in sea level will determine the ease with which this sediment is transported basinward. The sediment will most likely reach deepwater in the form of turbidity flows, which travel across bathymetric contours, only to be “blown” parallel to these contours as the finer sediments cross a deepwater bottom-current. Other sources of terrigenous sediment may include airborne and seaborne volcanoclastic debris.
Biogenic deposition from suspension may also supply sediment to these deepwater bottom-currents. The deposition of this material has strong implications for the biology, chemistry and flow conditions at the time. It must occur in areas of high biogenic productivity, during periods of relatively quiet flow and, if calcareous, must also occur at depths above the carbonate compensation depth. There is also a contribution to the concentration of suspended sediment by the burrowing activity of benthic organisms.
Geomorphology.
The accumulation and geomorphology of contourite deposits are mainly influenced by three factors: intensity of deepwater bottom-currents, seafloor topography, and sediment supply. There are five main types of contourite accumulations: giant elongate drifts, contourite sheets, channel related drifts, confined drifts and modified drift-turbidite systems.
Giant elongate drifts.
Giant elongate drifts form very large mounded elongated geometries parallel to the deepwater bottom-current flow. They are characterized by a near complete lack of parallel bedding. Mounded drifts are often bounded on one or both sides by non-depositional or erosional channels, sometimes known as "moats". These drifts can be “tens to hundreds of kilometers long, tens of kilometers wide, and range from 0.1 to more than 1 km in relief above the surrounding seafloor”. Their length to width ratio ranges from 2:1 to 10:1. They can accumulate to thicknesses greater than 2 km and can form anywhere from the upper slope to the deepest parts of the basin depending on the specific location of the bottom-current. Sedimentation rates range from 20 – 100 m/Ma. They tend to be finer-grained with a lot of mud, silt and biogenic material. Coarse-grained contourites are very rare. They may also form detached or separated versions due to seafloor topography and flow conditions. Detached drifts are isolated and migrate downslope while separated drifts typically are asymmetric in shape, tend to form at the base of a slope and migrate up-slope. Large sediment waves have been observed partially covering some giant elongate drifts.
Contourite sheets.
Contourite sheets are broad, low-relief features that extend through very large areas (i.e. ~1,000,000 km2) and are seen covering the abyssal plains or even plastered against the continental margins. They are characteristic of very deep water. They have a relatively constant thickness of up to a few hundred meters with a slight thinning towards the continental margin.
Sediment wave fields are a variety that is generally located near the rise to slope transition. Seismic reflection profiles show that the sediment waves tend to migrate up-slope.
Channel-related drifts.
Channel-related drifts form when deepwater bottom-currents are confined to a smaller cross sectional area of flow and therefore their velocity increases substantially. This can happen if the deepwater bottom-current is trapped within a deep channel or within a gateway that connects two basins. Due to the high velocities, it is common to see scours and erosional features as well as different types of deposits at the floor of the channel, the flanks, and the down-current exit of the channel.
Flank deposits are usually patchy and small (tens of km2), can be elongate and subparallel to flow direction and may have a sheeted or mounded geometry. At the down-current exit of the channel, flow velocity decreases dramatically and a cone-shaped contourite fan is formed which is much larger than the flank deposits, measuring about 100 km in radius and about 300 m in thickness. Channel floor deposits can be patchy and contain sand, gravel and mud clasts in the form of a channel lag.
Confined drifts.
Confined drifts are contourite accumulations that occur within small basins. The basins in which they form tend to be tectonically active in order to allow for topographic confinement of the deposit.
Modified drift-turbidite systems.
Modified drift-turbidite systems refer to the interactions of contourite and turbidite deposits. These can be observed as modifications of one another depending on the dominant process at the time. Examples range from asymmetric turbidite channel levees caused by strong deepwater bottom-currents as seen in the Nova Scotian Margin, to alternations in turbidite/debrite and contourite deposits both in time and space as seen in the Hebridean Margin. The Caledonia and Judith Fancy formations in St. Croix were studied by Stanley (1993) in which he found an ancient analog of an alternating turbidite and contourite deposit and generated a stratigraphic model of a continuum from a turbidite dominant environment to a contourite dominant one.
Distinguishing turbidites, contourites, and bottom-current modified turbidite deposits is essential for reconstructing the paleoenvironment in deepwater settings. Traction structures, such as cross-stratification, indicate bottom-current reworking because it is more likely to have avalanching in clear bottom-currents than it is in sediment saturated turbidity flows. Deposition from suspension in turbidity flows do not generate a sharp upper contact as bottom-current reworked deposits show due to the highly oscillating energy conditions. Stanley (1993) proposes that the transition from a turbidite to a contourite involves a continuous transition from a sandy deposit to lenticular bedding passing through wavy bedding.
Occurrence.
Present day.
Contourite deposition is active in many locations throughout the world, but particularly in areas affected by the thermohaline circulation.
Ancient examples.
Identifying contourites in ancient sedimentary sequences is difficult as their distinctive morphology becomes obscured by the effects of later bioturbation, sedimentation, erosion and compaction. Most examples of contourites identified in the geological record come from the Cenozoic but examples have been noted from as far back as the Ediacaran.


Dalhousie Formation

The Dalhousie Formation is a geologic formation in Quebec. It preserves fossils dating back to the Devonian period.


Adams Argillite Formation

The Adams Argillite Formation is a geologic formation in Alaska. It preserves fossils dating back to the Cambrian period.


Finnentrop Formation

The Finnentrop Formation is a geologic formation in Germany. It preserves fossils dating back to the Devonian period.


Headless Formation

The Headless Formation is a geologic formation in Northwest Territories. It preserves fossils dating back to the Devonian period.


Kreyenhagen Shale

The Kreyenhagen Shale is a geologic formation in California. It preserves fossils dating back to the Paleogene period.


Mount Dall Formation

The Mount Dall Formation is a geologic formation in Alaska. It preserves fossils dating back to the Permian period.


Timeline of Ordovician research

This timeline of Ordovician research is a chronological listing of events in the history of geology and paleontology focused on the study of earth during the span of time lasting from 485.4–443.4 million years ago and the legacies of this period in the rock and fossil records.
18th century.
1780s.
1789
20th century.
1970s.
1978
21st century.
2010s.
2015


ImaGem Inc.

ImaGem Inc. is a gem information company based on patented technology for grading and identifying gems. The parent company, ImageStatistics, offers applications in imaging and image processing for the medical, pharmaceutical, manufacturing, chemical and quality assurance industries. ImaGem was created after 20 years of research done on human perception and ImageStatistics, a statistical tool developed by Dr. Lalit K. Aggarwal. ImaGem’s Systems employ advanced optics, imaging technology and proprietary software programs to automate and integrate diamond grading. In addition to evaluating the 4C’s of diamond grading, ImaGem also analyzes Light behavior information based on precise and repeatable measures; three complementary dimensions of brilliance, intensity and sparkle. ImaGem has created a system of uniquely identifying and registering (fingerprinting) a stone without any need for laser inscription. By offering all this information, ImaGem has promoted decision-making and efficiency in the gem industry supply chain. In 1998, ImaGem Inc. was incorporated in the state of Pennsylvania, USA after funding from a major retailer, Ben Franklin Technology Partnership, and private funding. The company has developed an integrated technology to collect image data for diamonds and gemstones, analyze it using direct measurement methodology and grade for precise and repeatable measurements.
Breakthroughs and technological advances.
Color.
Color grading of diamonds (see Diamond color) and gemstones is subjective - an individual compares a subject stone under a light source to a master stone and assigns a color grade. This approach is well-known to provide a color grade that is not repeatable because, in the past, there has been confusion among different methods of grading used in various labs. Because of this, ImaGem solved several problems which contribute to a lack of precision and repeatability in color grading.
All these factors therefore, in varying degrees, contribute to inconsistent color grading as it has been practiced in previous years.
ImaGem’s color grading system was designed based on measurements with a system error of 1/400 of 1% to achieve high levels of precision and repeatability. The system assigns grades within 1/3 of the color grading system used by major diamond grading labs. The color grading system corrects for weight and fluorescence and uses CIE Chromaticity System (see CIE 1931 color space).
Fluorescence.
The most frequent color of fluorescence in diamonds is blue, but it occurs in many other colors. Fluorescence may be exhibited at both short-wave and long-wave UV. The strength of fluorescence also varies from slight to high. The value of a diamond may be affected by the presence and strength of fluorescence in a diamond. As a matter of personal taste, some people prefer a diamond with fluorescence. Although some may disagree, it is generally thought that fluorescence may influence perception of body color in a diamond and hence, its color grade.
Standard fluorescence grading is done by a trained gemologist using master stones and assigning a grade after projecting short and long-wave UV. Since a standardized lighting source has not yet been defined, and because of the subjective nature of the process, fluorescence grades in the past have not been repeatable.
Although instruments for measuring fluorescence have existed for some time, the process for measuring low-levels of fluorescence takes time and therefore may not be practical for fluorescence grading of diamonds. There are primarily three problems that need resolution to measure fluorescence accurately and repeat ably.
Clarity.
In diamonds and gemstones there is a need to identify that a product sold is what it is claimed to be. Also, one needs to determine if a gemstone has been treated or filled, or manufactured using composites. In rough gemstones, presence of foreign matter and inclusions affects the value of the rough material and is considered in planning how the stone will be cut to manufacture polished gemstones. Features in rough as well as finished goods are also used to fingerprint a gemstone. Finally, once polished goods are manufactured they require an assessment of their quality based on presence or absence of inclusions. Any activity related to the above, in general, deals with clarity of a gemstone.
ImaGem developed patented technology to precisely map, and measure inclusions in gemstones. There were several technical challenges ImaGem had to overcome in order to map inclusions:
These problems were addressed in the system developed by ImaGem by selecting appropriate immersion fluids, lighting environment and imaging system (lens and camera).
ImaGem’s Clarity system was built to see the exact location of inclusions in rough and polished diamonds. In regards to rough stones, inclusions are seen without the need to add windows to evaluate prior to cutting. Stones are immersed, in a special fluid and then imaged to identify inclusions. Some images of rough, polished diamonds and composite ruby illustrate the use of this technology in the gem and jewelry industry. This technology has also been used in the manufacture of other products where it is important to evaluate the product for consistency and absence of foreign matter. In the gem and jewelry industry in particular, this technology is used for Kimberley Certification, valuation of an individual of a parcel of rough, identification and for clarity grading.
Light behavior.
A diamond is cut to bring forth its beauty as expressed by its Light Behavior (see light performance). Until recently, it was impractical to measure light behavior in a cut and polished diamond. Gemologists relied on the proportions of a diamond as a means to cut and grade brilliant diamonds. One way that several organizations have advanced a system of grading a diamond is by grading it based on its proportions. Another development has been to use mathematical models to predict the light behavior of a diamond and grade it on the predicted behavior. The third approach is to measure light behavior in a real diamond. ImaGem’s light behavior is based on Direct Measurement of light behavior in diamonds of different shapes and sizes, which means that it grades these stones based on a new set of measurements, instead of simply comparing them to other brilliant-cut stones. It has identified 3 characteristics of light behavior that are important to describe the beauty of a diamond. These factors are brilliance, sparkle and intensity.
Brilliance represents average grey scale value of pixels comprising the top view of a diamond. This particular characteristic is generally accepted in most systems interested in light behavior of a diamond. Sparkle is measured as variation of grey scale values among pixels within the perimeter of a diamond. ImaGem uses sparkle to identify the dynamic behavior (scintillation) when a diamond or light is moved. Intensity (contrast) is a new concept introduced by ImaGem to capture the pattern of dark and bright areas in a diamond. This particular characteristic is patented and represents an attribute of a diamond that takes into account figure ground segregation essential to human perception. These three measures of light behavior in a diamond, in summary, are derived from direct measurement, are objective, repeatable, and take into account human perception of visual objects.


Jake Matijevic (rock)

Jake Matijevic (or Jake M) is a pyramidal rock on the surface of Aeolis Palus, between Peace Vallis and Aeolis Mons ("Mount Sharp"), in Gale crater on the planet Mars. The approximate site coordinates are: .
The rock was encountered by the "Curiosity" rover on the way from Bradbury Landing to Glenelg Intrigue in September 2012 and measures about height and width.
The rock was named by NASA after Jacob Matijevic (1947–2012), a mathematician-turned-rover-engineer, who played a critical role in the design of the six-wheeled rover, but died just days after the "Curiosity" rover landed in August 2012. Matijevic was the surface operations systems chief engineer for the Mars Science Laboratory Project and the project's "Curiosity" rover. He was also a leading engineer for all of the previous NASA Mars rovers including "Sojourner", "Spirit" and "Opportunity".
The rover team determined the rock to be a suitable target for the first use of "Curiosity"s contact instruments, the Mars Hand Lens Imager (MAHLI) and the Alpha particle X-ray spectrometer (APXS).
Analytical studies, performed on the rock by the "Curiosity" rover in October 2012, suggest the "Jake M" rock is an igneous rock but found to be high in elements consistent with feldspar, such as sodium, aluminum and potassium, and lower concentrations of magnesium, iron and nickel than other such rocks previously found on Mars. The mineral content and elemental abundance indicates "Jake M" rock may be a mugearite, a sodium rich oligoclase-bearing basaltic trachyandesite. Igneous rocks similar to the "Jake M" rock are well known but occur rarely on Earth. On Earth, such rocks form when magma, usually found in volcanoes, rises to the surface, cools and partially solidifies with certain chemical elements, while the warmer liquid magma portion becomes enriched with the left-behind elements. By remarkable coincidence, the Martian locality Glenelg is also the name of a small settlement in north-west Scotland that is east of type locality for mugearite at Mugeary on the island of Skye. The "Jake M" rock is a ventifact with a volcanic fabric. Its pyramidal shape was formed by eolian drifted grains of sand. The little cavities on its surface were formed by the blast-effect, which is caused by different flow dynamics at the micro-relief. On the surface one could see the marks of the main wind direction, by which "Jake M" was formed. On September 27, 2013, NASA scientists reported that "Jake M" rock was a mugearite and very similar to terrestrial mugearite rocks.


Accommodation (geology)

Accommodation is a fundamental concept in sequence stratigraphy, a subdiscipline of geology. It is defined as the space that is available for the deposition of sediments. Accommodation space can be pictured as the volume between the actual surface and the theoretical equilibrium surface where deposition and erosion are in balance at every point. In marine environments, this equilibrium level is sea level.
In marine environments, changes in accommodation on long temporal scales is mainly determined by tectonics or by changes in eustatic sea level. In fluvial environments, changes in accommodation are controlled by the gradient, discharge and sediment supply. In the lower parts of river systems, the change of accommodation in the fluvial system is controlled by the changes in marine accommodation.
The term is also sometimes used to described processes by which room is made for plutons to intrude country rock.


Somma volcano

A somma volcano (also known as a sommian) is a volcanic caldera that has been partially filled by a new central cone. The name comes from Mount Somma, a stratovolcano in southern Italy with a summit caldera in which the upper cone of Mount Vesuvius has grown.
A number of Earth's best examples of somma volcanoes are found on Russia's Kamchatka Peninsula and the Kuril Islands that stretch south from Kamchatka to Hokkaidō (Japan).
Some examples of somma volcanoes are the following:


Gene Autry Shale

The Gene Autry Shale is a geologic formation in Oklahoma. It preserves fossils dating back to the Carboniferous period.


Locatelli Formation

The Locatelli Formation is a geologic formation in California. It preserves fossils dating back to the Paleogene period.


Passamari Formation

The Passamari Formation is a geologic formation in Montana. It preserves fossils dating back to the Paleogene period.


Lanvoy Formation

The Lanvoy Formation is a geologic formation in France. It preserves fossils dating back to the Devonian period.


Ferhat Ozcep

Ferhat Ozcep is geophysicist and historian of science in Turkey. He was born in Zonguldak (the western Black Sea side of Turkey) on January 23, 1968. He was a visiting scholar in the Department of the Science at Harvard University. He currently is professor of geophysics at Istanbul University..
He received the B.Sc. degree in Geophysical Engineering from University of Istanbul in 1991 and the Pre-Bachelor's (Associate's) degree in Electrical Engineering Technician Program from Hacettepe University in 1992. He received the M.Sc. Degree in Geophysical Engineering from University of Istanbul in 1994. He received the Ph. D. degree in Geophysics from University of Istanbul in 1999. Between 1992 and 2004 years, he was a research assistant in Department of Geophysical Engineering, at University of Istanbul. In 1994 and 1996, he was elected a Member (as a general secretary) of Executive Committee of Istanbul Branch of “Chamber of Geophysical Engineers” that is only Geophysical Society in Turkey. Between 2006 and 2008, he was a Member of Executive Committee of “Union of Chambers of Turkish Engineers and Architects”. He was selected as a Member of History of Geophysics Committee, American Geophysical Union for the term 1 July 2002 to 30 June 2004. He is also a member of Geophysical Engineering Committee of ASCE
He is a member of American Geophysical Union, European Geosciences Union, Deutsche Geophysikalische Geselschaft (German Geophysical Society), American Society of Civil Engineers (ASCE), Chamber of Geophysical Engineers of Turkey, Earthquake Engineering Association of Turkey, and Turkish Society for History of Science.
His current research interests in geophysics focus on a wide range of topics: “Geotechnical Earthquake Engineering”, “Soil Dynamics”, “Seismic Microzonation”, “Paleomagnetism-Geomagnetism”, “Tectonophysics (Geodynamics)”, “Electromagnetic Techniques”, “Archeogeophysics”, “Exploration and Protection of the Nature (Environmental Geophysics)”, and “History and Philosophy of Science”.
He has been a Visiting Scholar in the Department of History and Philosophy of Science at University of Cambridge for Lent term 2015, where he has attended seminars and lectures run by the Department and has made use of the Department and University's facilities. Whilst he was in the Department, his sponsor was Professor Jim Secord.
While at Harvard, Prof. Ozcep will be conducting research on the “Investigation on Geophysical Ideas and Measurements in Ottoman Geography in Transition from Pre-Modern (Islamic) to Modern (Western) Periods.”
He was named co-chair of Department of Geophysical Engineering at Istanbul University-Cerrahpaşa in July 2018.


Ludlow Formation

The Ludlow Formation is a geologic formation in western North Dakota. It preserves fossils dating back to the Paleogene Period.


Timeline of Devonian research

This timeline of Devonian research is a chronological listing of events in the history of geology and paleontology focused on the study of earth during the span of time lasting from 419.2 to 358.9 million years ago and the legacies of this period in the rock and fossil records.
19th century.
1844
1859
1881
1889
1894
20th century.
1932
1937
1952
1956
1968
21st century.
2006
2010


Magnoavipes

Magnoavipes is an ichnogenus of dinosaur footprint. In 2016, it was found to belong to an oviraptorasaur and estimated the size of the animal at 6.9 meters (22.6 ft) and 1.3 tonnes (1.43 short tons). The footprint was 60 cm (2 ft) long.


Fort Preston Sand

The Fort Preston Sand is a geologic formation in Florida. It preserves fossils dating back to the Neogene period.


Hamburg Formation

The Hamburg Formation is a geologic formation in Nevada. It preserves fossils dating back to the Cambrian period.


Sedimentary basin

Sedimentary basins are regions of the Earth where long-term subsidence creates accommodation space for accumulation of sediments. As the sediments are buried, they are subject to increasing pressure and begin the processes of compaction and lithification that transform them into sedimentary rock.
Sedimentary basins occur in diverse geological settings usually associated with plate tectonic activity. Tectonic processes that lead to subsidence include the thinning of underlying crust; sedimentary, volcanic, or tectonic loading; or changes in the thickness or density of adjacent lithosphere.
Basins are classified by their tectonic setting (divergent, convergent, transform, intraplate), the proximity of the basin to the active plate margins, and whether oceanic, continental or transitional crust underlies the basin. Basins formed in different tectonic regimes vary in their preservation potential. On oceanic crust, basins are likely to be subducted, while marginal continental basins may be partially preserved, and intracratonic basins have a high probability of preservation.
Sedimentary basins are of great economic importance. Almost all the world's natural gas and petroleum and all of its coal are found in sedimentary rock. Many metal ores are found in sedimentary rocks formed in particular sedimentary environments.
Methods of formation.
Sedimentary basins form primarily in convergent, divergent and transform settings. Convergent boundaries create foreland basins through tectonic compression of oceanic and continental crust during lithospheric flexure. Tectonic extension at divergent boundaries where continental rifting is occurring can create a nascent ocean basin leading to either an ocean or the failure of the rift zone. In tectonic strike-slip settings, accommodation spaces occur as transpressional, transtensional or transrotational basins according to the motion of the plates along the fault zone and the local topography pull-apart basins.
Lithospheric stretching.
If the lithosphere is caused to stretch horizontally, by mechanisms such as "ridge-push" or "trench-pull", the effect is believed to be twofold. The lower, hotter part of the lithosphere will "flow" slowly away from the main area being stretched, whilst the upper, cooler and more brittle crust will tend to fault (crack) and fracture. The combined effect of these two mechanisms is for the Earth's surface in the area of extension to subside, creating a geographical depression which is then often infilled with water and/or sediments. (An analogy might be a piece of rubber, which thins in the middle when stretched.)
An example of a basin caused by lithospheric stretching is the North Sea – also an important location for significant hydrocarbon reserves. Another such feature is the Basin and Range Province which covers most of the USA state of Nevada, forming a series of horst and graben structures.
Another expression of lithospheric stretching results in the formation of ocean basins with central ridges; The Red Sea is in fact an incipient ocean, in a plate tectonic context. The mouth of the Red Sea is also a tectonic triple junction where the Indian Ocean Ridge, Red Sea Rift and East African Rift meet. This is the only place on the planet where such a triple junction in oceanic crust is exposed subaerially. The reason for this is twofold, due to a high thermal buoyancy of the junction, and a local crumpled zone of seafloor crust acting as a dam against the Red Sea.
Lithospheric compression/shortening and flexure.
If a load is placed on the lithosphere, it will tend to flex in the manner of an elastic plate. The magnitude of the lithospheric flexure is a function of the imposed load and the "flexural rigidity" of the lithosphere, and the wavelength of flexure is a function of flexural rigidity alone. Flexural rigidity is in itself, a function of the lithospheric mineral composition, thermal regime, and effective elastic thickness. The nature of the load is varied. For instance, the Hawaiian Islands chain of volcanic edifices has sufficient mass to cause deflection in the lithosphere.
The obduction of one tectonic plate onto another also causes a load and often results in the creation of a foreland basin, such as the Po basin next to the Alps in Italy, the Molasse Basin next to the Alps in Germany, or the Ebro basin next to the Pyrenees in Spain.
Strike-slip deformation.
Deformation of the lithosphere in the plane of the earth (i.e. such that faults are vertical) occurs as a result of near horizontal maximum and minimum principal stresses. The resulting zones of subsidence are known as strike-slip or pull-apart basins. Basins formed through strike-slip action occur where a vertical fault plane curves. When the curve in the fault plane moves apart, a region of "transtension" results, creating a basin. Another term for a transtensional basin is a "rhombochasm". A classic rhombochasm is illustrated by the Dead Sea rift, where northward movement of the Arabian Plate relative to the Anatolian Plate has caused a rhombochasm.
The opposite effect is that of "transpression", where converging movement of a curved fault plane causes collision of the opposing sides of the fault. An example is the San Bernardino Mountains north of Los Angeles, which result from convergence along a curve in the San Andreas fault system. The Northridge earthquake was caused by vertical movement along local thrust and reverse faults "bunching up" against the bend in the otherwise strike-slip fault environment.
In Nigeria, the dominant type of basement rock intersected by wells drilled for hydrocarbons, limestone, or water is granite. The three sedimentary basins in Nigeria are underlain by continental crust except in the Niger delta, where the basement rock is interpreted to be oceanic crust. Most of the wells that penetrated the basement are in the Eastern Dahomey embayment of western Nigeria. A maximum thickness of about 12,000 m of sedimentary rocks is attained in the offshore western Niger delta, but maximum thicknesses of sedimentary rocks are about 2,000 m in the Chad basin and only 500 m in the Sokoto embayment.
Ongoing development.
As more and more sediment is deposited into the basin, the weight of all the newer sediment may cause the basin to subside further because of isostasy. A basin can continue having sediment deposited into it, and continue to subside, for long periods of geological time; this can result in basins many kilometres in thickness. Geologic faults can often occur around the edge of, and within, the basin, as a result of the ongoing slippage and subsidence.
Study of sedimentary basins.
The study of sedimentary basins as a specific entity in themselves is often referred to as basin modelling or sedimentary basin analysis. The need to understand the processes of basin formation and evolution are not restricted to the purely academic. Indeed, sedimentary basins are the location for almost all of the world's hydrocarbon reserves and as such are the focus of intense commercial interest.


Pleito Formation

The Pleito Formation is a geologic formation in California. It preserves fossils dating back to the Paleogene period.


A.J. Timothy Jull

A.J. Timothy Jull (born 18 December 1951) is a radiocarbon scientist and director of the University of Arizona's Accelerator Mass Spectrometer Laboratory, as well as Editor in Chief of Meteoritics & Planetary Science and "Radiocarbon: An International Journal of Cosmogenic Isotope Research". Dr. Jull's work spans numerous disciplines, from radiocarbon dating the Shroud of Turin, to looking for signs of life in Martian meteorites.
Early life and career.
Dr. Jull was born in Leeds, England. He graduated from the University of Bristol in 1976 with a PhD in Geochemistry, doing postdoctoral work at Cambridge and the Max Planck Institute. Jull earned the Kirk Bryan Award in 1997 for his contributions in geological studies of Yellowstone National Park. He remains a senior research scientist and professor with the Department of Geosciences at the University of Arizona.


Radulichnus

Radulichnus is an ichnogenus of trace fossil which resembles the marks produced by the action of a mollusc's radula on sediment. As an ichnogenus, its classification is based solely on "appearance", and does not necessarily imply anything of the affinity of the organism which produced the trace.
However, fossils of "Kimberella" have been found at or near the ends of "Radulichnus" traces, leading to the suspicion (accepted nearly as fact by some) that the traces were made by "Kimberella".


North Fork Toutle River

The North Fork Toutle River is a tributary of the Toutle River in southwestern Washington in the United States. The river has its headwaters near Spirit Lake, on the north side of Mount St. Helens, and flows to the Toutle River, about upstream of its confluence with the Cowlitz River. The largest tributary is the Green River, which joins near the unincorporated town of Toutle.
The North Fork's watershed was severely affected by the 1980 eruption of Mount St. Helens, which coated the valley with ash and filled it with successive mudflows. The result of the eruption was that many hillsides were stripped of forest, and as a result erosion has increased dramatically and the North Fork is now extremely laden with sediment. Previously, Spirit Lake was the source of the river, but eruptions blocked the outlet and Spirit Lake no longer drains directly into the North Fork; instead, a tunnel was excavated in 1985 to connect the lake with South Coldwater Creek, a tributary of the North Fork. Once a mature river, the North Fork has transformed into a braided stream of relatively young origin, and its valley floor is less than three decades old. The Toutle River Sediment Retention Structure was built by the U.S. Army Corps of Engineers on the river in 1989 to prevent this sediment from traveling downstream and clogging the shipping channel of the Columbia River.
The upper part of the North Fork Toutle River watershed was redirected to the crater of Mount St. Helens itself until 1982. The river's headstreams begin on a volcanic ash deposit roughly long and deep, which is the source of much of the excess sediment.


Leintwardine Beds

The Leintwardine Beds is a geologic formation in England. It preserves fossils dating back to the Silurian period.


Meade Peak Formation

The Meade Peak Formation is a geologic formation in Idaho. It preserves fossils dating back to the Permian period.


Felsic

In geology, felsic is an adjective describing igneous rocks that are relatively rich in elements that form feldspar and quartz. It is contrasted with mafic rocks, which are relatively richer in magnesium and iron. Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Felsic magma or lava is higher in viscosity than mafic magma/lava.
Felsic rocks are usually light in color and have specific gravities less than 3. The most common felsic rock is granite. Common felsic minerals include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars (albite-rich).
Terminology.
In modern usage, the term "acid rock", although sometimes used as a synonym, normally now refers specifically to a high-silica-content (greater than 63% SiO2 by weight) volcanic rock, such as rhyolite. Older, broader usage is now considered archaic. That usage, with the contrasting term "basic rock" (MgO, FeO, mafic), was based on an ancient concept, dating from the 19th century, that "silicic acid" (H4SiO4 or Si(OH)4) was the chief form of silicon occurring in siliceous rocks. Although this intuition makes sense from an acid-base perspective in aquatic chemistry considering water-rock interactions and silica dissolution, siliceous rocks are not formed by this protonated monomeric species, but by a tridimensional network of SiO44– tetrahedra connected to each others. Once released in water and hydrolyzed, these silica entities can indeed form silicic acid in aqueous solution.
The term "felsic" combines the words "feldspar" and "silica". The similarity of the resulting term "felsic" to the German "felsig", "rocky" (from "Fels", "rock"), is purely accidental. "Feldspar" is linked to German. It is a borrowing of "Feldspat". The link is therefore to German "Feld", meaning "field".
Classification of felsic rocks.
In order for a rock to be classified as felsic, it generally needs to contain more than 75% felsic minerals; namely quartz, orthoclase and plagioclase. Rocks with greater than 90% felsic minerals can also be called leucocratic, from the Greek words for white and dominance.
Felsite is a petrologic field term used to refer to very fine-grained or aphanitic, light-colored volcanic rocks which might be later reclassified after a more detailed microscopic or chemical analysis.
In some cases, felsic volcanic rocks may contain phenocrysts of mafic minerals, usually hornblende, pyroxene or a feldspar mineral, and may need to be named after their phenocryst mineral, such as 'hornblende-bearing felsite'.
The chemical name of a felsic rock is given according to the TAS classification of Le Maitre (1975). However, this only applies to volcanic rocks. If the rock is analyzed and found to be felsic but is metamorphic and has no definite volcanic protolith, it may be sufficient to simply call it a 'felsic schist'. There are examples known of highly sheared granites which can be mistaken for rhyolites.
For phaneritic felsic rocks, the QAPF diagram should be used, and a name given according to the granite nomenclature. Often the species of mafic minerals is included in the name, for instance, hornblende-bearing granite, pyroxene tonalite or augite megacrystic monzonite, because the term "granite" already assumes content with feldspar and quartz.
The rock texture thus determines the basic name of a felsic rock.


Nightingale Corona

Nightingale Corona is a corona found on the planet Venus. Latitude 63.6° North, Longitude 129.5° East. It has a diameter of 471 kilometers, and is the 35th largest corona on Venus.
It is named for Florence Nightingale, an English nurse. Coronae are conventionally named for goddesses: however, when it was first discovered it was thought to be a crater, and named accordingly. It was 1983 when it was closely observed by the radar imaging equipment aboard the Venera 15 and Venera 16 spacecraft, that its true nature became apparent.
Unlike the circular Aramaiti Corona, the Nightingale formation is more elliptical and irregular in shape.


Silver Creek Fault

The Silver Creek Fault is a potentially seismically active, northwest-southeast trending strike-slip fault structure in Santa Clara County, California. The Silver Creek Fault runs through and adjacent to the , Evergreen Basin, and generally lies parallel and between the Guadalupe River and Coyote Creek, running directly through the center of San Jose. It also runs parallel to the Hayward Fault, which is located to the east.
No historic activity of the Silver Creek Fault has been recorded. The City of San José considers the fault to be a rupture hazard only in the foothills but not in the Santa Clara Valley floor. Studies in 2003 and 2004 for the Silicon Valley BART extension, which will cross the fault, found that the northern segment may be as shallow as deep but found no evidence of surface rupture. A 2017 article suggests that the fault may have effectively become dormant or abandoned roughly .
Research in 2003 suggested that an extension of the Silver Creek Fault may run the entire length of the East Bay, but by 2010 the California Geological Survey's state Fault Activity Map had truncated the Silver Creek Fault south of Fremont.


McGregor Creek Formation

The McGregor Creek Formation is a geologic formation in British Columbia. It preserves fossils dating back to the Permian period.


Alexander du Toit

Alexander Logie du Toit FRS ( ; 14 March 1878 – 25 February 1948) was a geologist from South Africa and an early supporter of Alfred Wegener's theory of continental drift.
Early life and education.
Du Toit was born in Newlands, Cape Town in 1878, and educated at the Diocesan College in Rondebosch and the University of the Cape of Good Hope. Encouraged by his grandfather, Captain Alexander Logie, he graduated in 1899 in mining engineering at the Royal Technical College in Glasgow. After a short period studying geology at the Royal College of Science in London, he returned to Glasgow to lecture in geology, mining and surveying at the University of Glasgow and the Royal Technical College.
Career.
In 1903, du Toit was appointed as a geologist within the Geological Commission of the Cape of Good Hope, and he began to develop an extensive knowledge of the geology of southern Africa by mapping large portions of the Karoo and its dolerite intrusions, publishing numerous papers on the subject. Subsequently, he mapped the entire Karoo System through the complete stratigraphy from Dwyka tillite to the basalt of the Drakensberg. He worked at a furious rate but was known for his painstaking meticulousness, as reflected in his book "Our Wandering Continents". It still bears reading for its creative and closely argued theses in the light of the geology of the day, and is soberingly consistent with modern principles of plate tectonics.
In 1920, du Toit joined the Union Irrigation Department as water geologist, and in 1927, he became chief consulting geologist to De Beers Consolidated Mines until his retirement in 1941.
In 1923, he received a grant from the Carnegie Institution of Washington, and used this to travel to eastern South America to study the geology of Argentina, Paraguay and Brazil. As is apparent from his remarks in "Our Wandering Continents", he had requested support for the expedition not on a whim but specifically to test his predictions of correspondences between the geology of both continents. In the event, he was able to demonstrate and follow the predicted continuation of specific features that had already documented in Southern Africa into the continent of South America. Although it might perhaps seem less impressive to the layman, that evidence was far more convincing to the geologist than was the matching of continental shelves.
In the light of his research, du Toit published a review of the stratigraphic and radioisotope evidence from those regions that supported Wegener's ideas, "A Geological Comparison of South America with South Africa" (1927). His best-known publication, "Our Wandering Continents" (1937), expanded and improved this work and, departing somewhat from Wegener, proposed two original supercontinents separated by the Tethys Ocean, a northern/equatorial Laurasia and a southern/polar Gondwanaland.
Awards and honours.
In 1933, du Toit was awarded the Murchison Medal by the Geological Society of London, and in 1943, he became a Fellow of the Royal Society.
In 1949, the year after his death, the Geological Society of South Africa inaugurated a biennial lecture series in his honour that continues to the present day.
In 1973, a 75 km crater on Mars (71.8°S, 49.7°W) was named "Du Toit" in recognition of his work.


Denay Limestone

The Denay Limestone is a geologic formation in Nevada. It preserves fossils dating back to the Devonian period.


Merevale Shales

The Merevale Shales is a geologic formation in England. It preserves fossils dating back to the Ordovician period.


Thornloe Formation

The Thornloe Formation is a geologic formation in Quebec. It preserves fossils dating back to the Silurian period.


Peach Spring Tuff

The Peach Spring Tuff is a pyroclastic flow sheet deposit spanning 32,000 km2 in California, Arizona, and Nevada. The source of the Peach Spring Tuff is the Silver Creek Caldera located outside of Oatman, Az. The Silver Creek Caldera was found to be a match to the Peach Spring Tuff after an ignimbrite sample from within the caldera matched the phenocryst makeup and age of the Peach Spring Tuff. The caldera eruption is dated to the early Miocene, radiometrically dated to 18.78 +/- 0.02 Ma using argon-argon dating methods on sanidine crystals. The Peach Spring Tuff has a rhyolitic composition with thickness ranging from 10-140 m depending on location.The Peach Spring Tuff is the only geologic evidence of a super-eruption in this region.
Tectonic Setting.
The 32,000 km2 area containing the Peach Spring Tuff overlies multiple tectonic environments including a stable plateau, a normal faulting transition zone, a basin and region, the Colorado River Extensional Corridor, and a strike slip region. There is evidence that prior to the eruption that resulted in the Peach Spring Tuff there was uplift of the Colorado Plateau that exposed erosional surfaces underlying the Peach Spring Tuff and provided drainage slopes that impacted the direction of eruptive flow.
Magmatic System.
Data indicates that the magma body that erupted resulting in the Peach Spring Tuff was compositionally and texturally zoned, as well as zoned by temperature. The textural difference and transition from low to high silica content between intra-caldera ignimbrite and the Peach Spring Tuff indicates a shift from crystal-poor rhyolite to crystal-rich trachyte during the eruption. This transition can be assumed because the intra-caldera ignimbrite would have been the last to be erupted. The textural and compositional shift represents a zoned magma body because the first material to erupt is slightly different than the last material, indicating change from shallow magma to deep magma.
Silver Creek Caldera.
The span of the Peach Spring Tuff indicates that it resulted from a significant eruption, likely forming a large caldera in the process. It wasn't until 2008 that the Silver Creek Caldera was suggested as the source caldera for the Peach Spring Tuff. The Silver Creek Caldera is distinguished by a 450m trachyte ignimbrite that petrologically and geochemically match that of the Peach Spring Tuff. The major differences between the Peach Spring Tuff and the ignimbrite of the Silver Creek Caldera is that the majority of the Peach Spring Tuff is rhyolitic while the ignimbrite is trachytic, indicating the SiO2 content in the Peach Spring Tuff is higher than that of the ignimbrite.
Petrology.
The Peach Spring Tuff shows 5 different zones through textural differences as a result of thermal zoning in the caldera magma chamber. Phenocrysts of sanidine, plagioclase, biotite, amphibole, pyroxene, and the occasional quartz build between 4 and 14% of the Peach Spring Tuff composition; titanite, zircon, and apatite have also been found. The first four zones contain these lower percentages of phenocrysts while an increase can be seen in zone 5, the uppermost zone. From zone 1 to zone 4 there is an increase in phenocrysts within the pumice from 5% to 11% while from zone 4 to zone 5 there is an increase to between 18% and 23%, measured volumetrically.
Zone 5 of the Peach Spring Tuff is trachytic while the underlying zones are rhyolitic. This trachytic zone is most compositionally similar to the intra-caldera ignimbrite.


Sheepeater Cliff

The Sheepeater Cliffs are a series of exposed cliffs made up of columnar basalt in Yellowstone National Park in the United States. The lava was deposited about 500,000 years ago during one of the periodic basaltic floods in Yellowstone Caldera, and later exposed by the Gardner River. The cliffs are noted as a textbook example of a basaltic flow with well defined joints and hexagonal columns. They were named after a band of Eastern Shoshone known as "Tukuaduka" (sheep eaters). Many of the exposed cliffs are located along a steep inaccessible canyon cut by the Gardner near Bunsen Peak, but some of the cliffs located just off the Grand Loop Road can be reached by car.


Batesville Sandstone

The Batesville Sandstone is a geologic formation in northern Arkansas that dates to the Chesterian Series of the late Mississippian. The base of the Batesville Sandstone, named the Hindsville Limestone Member, unconformably lies on the Moorefield Formation.


Dinehichnus

Dinehichnus is an ichnogenus found in the Morrison Formation that is attributed to dryosaurid dinosaurs. The trackways are present in Saltwash Member outcrops at Boundary Butte in southernmost Utah. "Dinehichnus" trackways are frequently found in groups, traveling parallel to one another. From this it can be inferred that the "Dinehichnus" trackmaker was a social animal. "Dinehichnus" tracks preserve impressions of three widely splayed toes on feet that point inwardly, as well as heel marks.


Anita Mai Tan

Anita Mai Tan is a Canadian jewelry designer who is currently the owner and main designer of AlGems. She has designed rings, necklaces, smartphone cases, wine decanters and luxury pens. Anita has designed products for charitable causes, including a Dragon and Spider iPhone case necklace that was valued at approximately $880,000 for a charity auction to help youth with low income to remain at school . Her Dragon decanter contains 2,000 grams of 18K gold and encrusted with diamonds and gemstones for a total of 72 carats. Her work has been carried by one of the Japan's international department store Mitsukoshi Ltd.
In 2010, she designed her first luxury pen cover in diamond and gold. The body of the pen is made of gold and adorned with 48 carats of diamonds (1,888 gems). The pen is priced at €688,000 (approximately $1.01 million). She also designed a pair of luxury iPhone cases, the Dragon and Spider phone case. Both cases are made in 18K gold. The Dragon case consists of 2,200 colorless and colored diamonds (cognac, brown, champagne) with total weight of 32 carats while the spider case covered with an array of 2,800 colorless and black diamonds for a total weight of 38 carats.
In many of her works, Anita uses animal figures (dragon, horse, spider) as well as floral patterns. The numbers of stones deliberately match certain numbers with auspicious connotations in Chinese culture such the numbers nine (leadership, the ability to see clearly), 22 (easy), 28 (easy gaining wealth), 32 (born lucky) or 38 (worn wealth).


Orca Formation

The Orca Formation is a geologic formation in Alaska. It preserves fossils dating back to the Paleogene period.


Ma Jin (geologist)

Ma Jin (; 27 November 1934 – 12 August 2018) was a Chinese geophysicist and structural geologist. She was a senior research fellow at the Institute of Geology of the China Earthquake Administration, and an academician of the Chinese Academy of Sciences.
Biography.
Ma was born on 27 November 1934 in Rugao, Jiangsu, Republic of China. She studied at the Beijing Institute of Geology from 1952 to 1956. After graduation, she entered the Institute of Geology of the Chinese Academy of Sciences (CAS) to study structural geology under Zhang Wenyou (). In 1958, she went to the Soviet Union to study at the Institute of Tectonophysics, USSR Academy of Sciences, and earned an associate doctor degree (Ph.D. equivalent) in 1962.
After returning to China in 1962, she worked as an assistant researcher at the Institute of Geology of CAS. In 1978, she was transferred to the Institute of Geology of the China Earthquake Administration and promoted to associate research fellow. She became senior research fellow in 1981, and later served as Director of the institute's academic committee. She was a visiting scholar at the United States Geological Survey in 1983.
Ma made significant contributions in tectonophysics, specifically the mechanisms of tectonic deformation and its relations to seismic activity. She published over 200 scientific papers and several monographs, and won more than 10 national and ministerial awards. She was elected an academician of the Chinese Academy of Sciences in 1997.
Ma died in Beijing on 12 August 2018, at the age of 83.


Gerster Formation

The Gerster Formation is a geologic formation in Utah. It preserves fossils dating back to the Permian period.


Messel Formation

The Messel Formation is a geologic formation in Hesse, central Germany, dating back to the Eocene epoch (about 47 Ma). Its geographic range is restricted to the Messel pit. There it unconformably overlies crystalline Variscan basement and its Permian cover (Rotliegend) as well as Eocene volcanic breccias derived from the basement rocks. The formation mainly comprises lacustrine laminated bituminous shale (‘oil shale’) renowned for its content of fossils in exceptional preservation, particularly plants, arthropods and vertebrates (e.g. "Darwinius masillae").


Catahoula Formation

The Catahoula Formation is a geologic formation in Texas and Louisiana. It preserves fossils dating back to the Paleogene period.


Johns Wash Limestone

The Johns Wash Limestone is a geologic formation in Nevada. It preserves fossils dating back to the Cambrian period.


Downton Castle Sandstone

The Downton Castle Sandstone is a geologic formation in England. It preserves fossils dating back to the Silurian period. As its name would suggest the formation predominantly consists of sandstone with minor siltstone and mudstone. The oldest known Trigonotarbid "Palaeotarbus" is known from the formation.


Zmija Facula

Zmija Facula is a bright region on the surface of Mercury, located within an unnamed crater that is itself within the larger Rembrandt basin. It was named by the IAU in June 2020. "Zmija" is the Serbian word for snake.


Picrite basalt

Picrite basalt or picrobasalt is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine. It is dark with yellow-green olivine phenocrysts (20-50%) and black to dark brown pyroxene, mostly augite.
The olivine-rich picrite basalts that occur with the more common tholeiitic basalts of Kīlauea and other volcanoes of the Hawaiian Islands are the result of accumulation of olivine crystals either in a portion of the magma chamber or in a caldera lava lake. The compositions of these rocks are well represented by mixes of olivine and more typical tholeiitic basalt.
The name "picrite" can also be applied to an olivine-rich alkali basalt: such picrite consists largely of phenocrysts of olivine and titanium-rich augite pyroxene with minor plagioclase set in a groundmass of augite and more sodic plagioclase and perhaps analcite and biotite.
Picrites and komatiites are somewhat similar chemically, but differ in that komatiite lavas are products of more magnesium-rich melts, and good examples exhibit the spinifex texture. In contrast, picrites are magnesium-rich because crystals of olivine have accumulated in more normal melts by magmatic processes. Komatiites are largely restricted to the Archean.
When the term "oceanite" was apparently first proposed by Antoine Lacroix, he used the term to apply only to basalts with more than 50% olivine content (an extremely rare occurrence). Picrite basalt is found in the lavas of Mauna Kea and Mauna Loa in Hawaii, Curaçao, in the Piton de la Fournaise volcano on Réunion Island and various other oceanic island volcanoes.
Oceanite.
Oceanite is the name of variety of picritic basalt characterized by its large amounts of olivine phenocrysts and lesser amounts of augite and by having a groundmass of olivine, plagioclase and augite. The term was coined by Antoine Lacroix in 1923.
Common uses.
Olivine basalt is commonly used by foundries, boilermakers and boiler users to protect the area around a burner tip or to protect a floor from molten metal and other slag. Its use in this fashion is appropriate since olivine is a highly refractory, high-melting-temperature mineral.


Bone bed

A bone bed is any geological stratum or deposit that contains bones of whatever kind. Inevitably, such deposits are sedimentary in nature. Not a formal term, it tends to be used more to describe especially dense collections such as Lagerstätte. It is also applied to brecciated and stalagmitic deposits on the floor of caves, which frequently contain osseous remains.
In a more restricted sense, the term is used to describe certain thin layers of bony fragments, which occur in well-defined geological strata. One of the best-known of these is the Ludlow Bone Bed, which is found at the base of the Downton Sandstone in the Upper Ludlow series. At Ludlow (England) itself, two such beds are actually known, separated by about . of strata. Although quite thin, the Ludlow Bone Bed can be followed from that town into Gloucestershire, for a distance of . It is almost completely made up of fragments of spines, teeth and scales of ganoid fish. Another well-known bed, formerly known as the Bristol or Lias Bone Bed, exists in the form of several thin layers of micaceous sandstone, with the remains of fish and saurians, which occur in the Rhaetic Black Paper Shales that lie above the Keuper marls, in the south-west of England. A similar bone bed has been traced on the same geological horizon in Brunswick, Hanover (Germany), in Franconia and in Tübingen (Germany). A bone bed has also been observed at the base of the Carboniferous limestone series, in certain parts of the south-west of England.
Bone beds are also recorded in North America, South America, Mongolia and China. Terrestrial bonebed examples are: the Triassic "Metoposaurus" bone bed from Portugal, the "Mapusaurus" bone bed at Cañadón del Gato, in Argentina, the "Allosaurus"-dominated Cleveland-Lloyd Dinosaur Quarry of Utah, the Dinosaur National Monument on the boundary of Utah and Colorado, an "Albertosaurus" bone bed from Alberta, a "Daspletosaurus" bone bed from Montana, the Cenozoic John Day Fossil Beds of Oregon and the Nemegt Basin in the Gobi Desert region of Mongolia. Bentiaba, Angola, is an example of a marine bonebed with numerous mosasaurs and plesiosaurs.


Millbuie Sandstone

The Millbuie Sandstone is a geologic formation in Scotland. It preserves fossils dating back to the Devonian period.