Lunar Sample Laboratory Facility

The Lunar Sample Laboratory Facility (LSLF) is a repository and laboratory facility at NASA's Lyndon B. Johnson Space Center in Houston, Texas, opened in 1979 to house geologic samples returned from the Moon by the Apollo program missions to the lunar surface between 1969 and 1972. The facility preserves most of the of lunar material returned over the course of Apollo program and other extraterrestrial samples, along with associated data records. It also contains laboratories for processing and studying the samples without contamination.
History.
Planning for handling returned lunar samples began early in the Apollo program. In 1964, a proposal was made for a small () sample receiving laboratory equipped with remote-controlled manipulators operating in a sterile, high-vacuum chamber to prepare samples for distribution to scientists, and this proposal was subsequently expanded to include a clean room with analytical instruments for performing preliminary analyses on the samples.
A committee of the Space Science Board reviewed the idea of a lunar sample receiving laboratory and sought to address multiple concerns. One was the fear that creating a facility with too great a capacity to analyze the samples would discourage distribution of samples to outside researchers and effectively exclude them. In addition, space biologists and the United States Public Health Service expressed concern about "back contamination" of Earth by extraterrestrial microorganisms brought back via returning spacecraft, (although many of the astronauts and scientists involved in the program were skeptical that non-terrestrial microorganisms could survive lunar conditions). To address these issues, the committee in 1965 recommended a laboratory with limited analytical capacity and an ability to quarantine the returning astronauts and samples.
The result of this planning was the Lunar Receiving Laboratory (LRL) in Building 37 at the Johnson Space Center, built to process and conduct basic analysis on lunar materials and to quarantine the materials and astronauts. (The requirement that astronauts be quarantined following their missions was dropped beginning with Apollo 15.) The LRL was completed in 1967 at a cost of $7.8 million. The LRL was used for study, distribution and safe storage of the samples, but although the LRL had adequate facilities to process samples for the current mission, the facility was not ideal, and it lacked facilities to process or store samples from previous missions. To address some of these concerns, NASA dropped the requirement after Apollo 12 that samples be processed in vacuum (in favor of a simpler-to-work-in nitrogen atmosphere). An additional vault and, subsequently, a new laboratory – the Sample Storage and Processing Laboratory (SSPL) – were built in Building 31 of the Johnson Space Center. All lunar samples were moved from the LRL to Building 31 after the last Apollo mission
Nonetheless, there were still concerns about the adequacy of the facility and about the wisdom of maintaining the entire collection of lunar samples in a single facility that might be vulnerable to natural disasters (especially the hurricanes to which Houston is vulnerable) and military actions. The collection was divided among multiple vaults at the Johnson Space Center while a vault was built in an empty ammunition bunker at Brooks Air Force Base in San Antonio, Texas as second-site storage. Fourteen percent of the lunar sample collection was moved to this bunker in 1976, transported secretly at night with a police escort in a specially modified passenger bus. This smaller collection of materials remained at Brooks until 2002, when the base was transitioned from military control as part of the Base Realignment and Closure process. The second-site lunar materials were then moved to the White Sands Test Facility, where a new, smaller facility was built inside an existing secure building to house the samples. Of the of lunar samples returned by the Apollo program, are currently stored at White Sands.
With a selection of the lunar samples secured offsite, construction began on the LSLF, with state-of-the-art facilities for handling the samples and better protection against natural disasters. The LSLF was constructed in a new annex of Building 31 (Building 31N at the Johnson Space Center) beginning in 1977. Built for a cost of $2.5 million, the building was dedicated on July 20, 1979, the tenth anniversary of the first manned Moon landing.
Features.
The two-story, facility consists of storage vaults for the samples, laboratories for sample preparation and study, a vault for sample data and records, and machinery to supply nitrogen to the cabinets in which the samples are stored and processed.
The facility's storage vaults are elevated above anticipated storm-surge sea level heights to protect the samples from threats posed by hurricanes and tornadoes. During hurricane threats, a water-tight door is bolted into the frame of the door to the pristine sample vault in order to protect the samples.
The facility takes extensive measures to prevent contamination of the lunar samples. For example:
The facility has room to store many more lunar samples. NASA anticipates that more samples from the Moon will be brought back and processed and curated in the lab.
Samples stored at facility and other lunar samples.
The facility is the chief repository of the samples returned by the Apollo program. The Apollo missions to the lunar surface (Apollo 11, Apollo 12, Apollo 14, Apollo 15, Apollo 16, and Apollo 17) returned a total of 382 kilograms (842 pounds) of lunar rocks, core samples, pebbles, sand and lunar surface dust, comprising 2200 individual specimens. Seventy-five percent of the lunar materials returned by Apollo are housed at the Lunar Sample Laboratory Facility, most in pristine condition. Some of the materials have been processed into smaller samples to meet scientific requirements, resulting in more than 110,000 individually cataloged samples.
Perhaps the most notable of the samples stored at the facility is the Genesis Rock, a sample ultimately determined to be nearly as old as the Moon itself. Also at the facility is the sample known as Big Muley, the largest sample returned from the Moon by Apollo.
In addition to the Apollo materials, the Johnson Space Center also houses other extraterrestrial samples:
 of the of lunar samples returned by the Apollo program are stored at the White Sands Test Facility. Other small samples have been distributed to foreign heads of state, U.S. states, museums, and other institutions. NASA has also made a number of educational packs available for exhibition and educational purposes, each consisting of a disc of six small rock and soil samples in a lucite disc and a pack of thin petrological sections.
In addition to the lunar samples returned by the Apollo missions, an additional of lunar samples were returned to Earth by three automated Soviet spacecraft, Luna 16, Luna 20, and Luna 24.
Access to facility and samples.
Approximately 100 people visit the facility annually for research or educational purposes, and the facility provides samples to hundreds of others each year for research or educational purposes.
Researchers seeking samples submit proposals, which are evaluated by an independent peer review panel. 40 to 50 such proposals are approved each year and approximately 400 lunar samples (most weighing less than one gram) are sent to these scientists.


Chattanooga Shale

The Chattanooga Shale is a geologic formation in Alabama, Arkansas, Kentucky, Missouri and Tennessee. It preserves conodont fossils dating to the Devonian Period. It occurs mostly as a subsurface geologic formation composed of layers of shale. It is located in Eastern Tennessee and also extends into southeastern Kentucky, northeastern Georgia, and northern Alabama. This part of Alabama is part of the Black Warrior Basin.
The Chattanooga Shale of east Tennessee is reported to be an extension of or correlates with the Marcellus Shale of the Appalachian region to the east. Exploratory drilling of the Chattanooga Shale in east Tennessee indicates that it contains significant amounts of natural gas. This has resulted in interest in and attempts to use hydraulic fracturing to exploit the resource.


East Mountain Shale

The East Mountain Shale is a geologic formation in Texas. It preserves fossils dating back to the Carboniferous period.


Indusial Limestone

The Indusial Limestone is a geologic formation in France. It preserves fossils dating back to the Neogene period.


Hopkinton Dolomite

The Hopkinton Dolomite is a geologic formation in Iowa. It preserves fossils dating back to the Silurian period.


Wych Beds

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


Barrel Spring Formation

The Barrel Spring Formation is a geologic formation in California. It preserves fossils dating back to the Ordovician period.


Bristol Dinosaur Project

The Bristol Dinosaur Project is a public engagement and educational initiative run by the University of Bristol. It began in 2000, and since then the Bristol Dinosaur Project team has visited hundreds of schools and spoken to tens of thousands of children, as well as appearing at science fairs in Bristol and elsewhere.
Background.
The Bristol dinosaur, "Thecodontosaurus antiquus", was found in 1834, and named in 1836, and did not achieve much recognition locally, either at the time of discovery, in the 1830s, nor later, when it was restudied, in the 1870s, 1900s, or 1990s. Then, after the re-examination of specimens collected in the 1830s, still located in Bristol City Museum and Art Gallery, and the collection of additional specimens from Tytherington quarry, in the 1970s, local palaeontologists and geologists realised there was potential to use the newly reinvigorated research programme as a means to include the public, especially local children, in the excitement of scientific discovery.
Funding.
Initially, the Bristol Dinosaur Project was funded by the University of Bristol using widening participation funds. These were funds intended to reach out to local schools that did not have a reputation for sending many children to university. By sending students to visit those schools, it was hoped that children might be inspired, work hard, and then later apply to study at university.
Then, the Bristol Dinosaur Project received substantial funding from the Heritage Lottery Fund, and it was able to operate at a much more ambitious level, from 2010-2013. After that funding cycle, the University of Bristol continued funding of the project for widening participation purposes.
Engagement.
From the start, the Bristol Dinosaur Project sought to engage children in two age groups, 7- to 9-year-olds, and 14- to 15-year-olds. With younger children, it has always been very easy to engage their enthusiasm – it is enough to pass round a dinosaur bone or tooth, and they are thrilled to be handling the real thing. With the teenagers, it is more important to let them see how much fun a career in science, or a related field, can be. At that age, young people are making important choices that may affect the rest of their lives - whether to engage with their academic studies or not, whether to focus on science or other disciplines.
A recent evaluation report about the Bristol Dinosaur Project by David Owen, summarised the learning and engagement side of the project as follows:
Since May 2010 the project engaged with over 136 schools and more than 13,200 pupils. The majority of these pupils were Key Stage 1-2 (11,000) with the remainder being Key Stage 3-4 (2,000). In total the project delivered 216 day visits to schools, reaching schools across Bristol, North Somerset, South Gloucestershire and Bath and North East Somerset. The project also visited some schools in Somerset, Dorset, Wiltshire, South Wales, Gloucestershire and one in the West Midlands. Interviews confirmed that the project had developed an excellent reputation across the city with teachers, schools and organisations that support schools. This was largely attributed to the high quality resources and the professionalism of the volunteers and staff delivering the workshop. A major part of the schools’ outreach was the development of fossil walks; these were particularly targeted at Key Stage 3-4. Young people had the chance to visit Aust Cliffs, South Gloucestershire or Charmouth, Dorset, to find fossils and discover more about how they formed and what life was like in the past.
In addition to its work with schools, the project team developed a wide range of partnerships with organisations across the city, in order to better engage new audiences and hard-to-reach adults and young people with the project. Evidence collected for this report suggested that the partnerships would have lasting impacts beyond the HLF funding, and in particular had connected the discovery of the Bristol Dinosaur with the cultural heritage of the city.
In three years the project visited a wide range of annual or one-off public events and festivals including the Bristol Festival of Nature, At-Bristol, the Cheltenham Science Festival, Arnos Vale Cemetery, libraries across South Gloucestershire, and Bristol's City Museum & Art Gallery. The project visited over 30 one-off or annual events in total, with the project team estimating a reach of 18, 000 people (children and adults). These figures do not include the 650,000 people who visit the Bristol Zoo each year.
The reach of the Bristol Dinosaur Project was recognised as a key success, and is a major part of how the project reached new audiences. However, in building the partnerships that delivered this reach, the project was able to piggyback on the efforts of other organisations to engage hard-to-reach groups of young people and adult. The project also sought to involve adults and young people from hard-to-reach groups in a more sustained and transformational manner.
In 2018, the Bristol Dinosaur Project was featured in the "Jurassic Make Off" series, a sponsored YouTube collaboration between the Let's Play channels Game Grumps and The Yogscast, where Education Officer Rhys Charles was cast as a competition judge alongside Ben Ebbrell of Sorted Food.
Laboratory work.
Laboratory work has always been the key component of the Bristol Dinosaur Project. The 1975 find from Tytherington Quarry consisted of some 4 tonnes of fossiliferous rock, and numerous technical staff and student volunteers have laboured over the years to remove the fossilized bones from the rock.
The HLF funding allowed one side of a new palaeontology laboratory to be built at the University of Bristol. This was used for the preparation and curatorial work done with over 4 tonnes of rock containing the remains of "Thecodontosaurus" and associated micro-fauna. For the first 2 years, the creation and development of a new research collection was one of the main activities in the laboratory. A new volunteering program was developed at the University, and hundreds of volunteers (University students and external volunteers) worked under the preparator's guidance and supervision in order to process several hundred kilograms of rock by means of acid digestion, mostly using acetic acid. This process, even though very slow and painstaking, provided great results for the project's laboratory and research team: several thousand microfossils were recovered, studied and classified. The implementation of a new summer research program enabled undergraduate and master students to take part in top research projects, with the aim for scientific publications, while developing their laboratory and scientific skills.
The second year of the project marked the beginning of curatorial and preparation work. Tons of rock were prepared using mechanical or chemical techniques. Thousands of dinosaur bones were extracted and fully curated into a new research collection. Both micro- and macrofossil collections are now housed at the University's museum, and are available for further research studies.


Val Formation

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


Chalk Hills Formation

The Chalk Hills Formation is a geologic formation in Idaho. It preserves fossils dating back to the Neogene period.


Bronydd Formation

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


Lizard Springs Formation

The Lizard Springs Formation is a geologic formation in Trinidad and Tobago. It preserves fossils dating back to the Paleocene to Early Eocene period.


Montesano Formation

The Montesano Formation is a geologic formation in Washington (state). It preserves fossils dating back to the Neogene period.


Bois Formation

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


Cape Formation

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


Eyam Limestone

The Eyam Limestone is a geologic formation in England. It preserves fossils dating back to the Carboniferous period.


Friars Formation

The Friars Formation is a geologic formation in San Diego County, Southern California.
Geology.
It is the uppermost unit of the La Jolla Group. The rocks are nonmarine and lagoonal sandstone and claystone, named for exposures along the north side of Mission Valley near Friars Road.
It reaches a maximum thickness of between Mission Valley and Carmel Valley.
Fossils.
It preserves fossils dating back to the middle and late Eocene epoch of the Paleogene period, during the Cenozoic Era.


Croatan Formation

The Croatan Formation is a geologic formation in North Carolina. It preserves fossils dating back to the Neogene period.


Xcacau Corona

Xcacau Corona is a corona (geological formation in the form of crown) in the planet Venus, in the coordinates -56 ° S and 131 ° E.
It covers a circular surface about 200 kilometers in diameter. It is located in Henie Quadrangle.
The Xcacau Corona was named in 1997 in reference to the Xcacau, the K'iche' goddess of the cacao and fertility.


Belleville Formation

The Belleville Formation is a geologic formation in Kansas. It preserves fossils.


Drum Formation

The Drum Formation is a geologic formation in Kansas. It preserves fossils dating back to the Carboniferous period.


Linear ridge networks

Linear ridge networks are found in various places on Mars in and around craters. These features have also been called "polygonal ridge networks," "boxwork ridges", and "reticulate ridges." Ridges often appear as mostly straight segments that intersect in a lattice-like manner. They are hundreds of meters long, tens of meters high, and several meters wide. It is thought that impacts created fractures in the surface, these fractures later acted as channels for fluids. Fluids cemented the structures. With the passage of time, surrounding material was eroded away, thereby leaving hard ridges behind.
It is reasonable to think that on Mars impacts broke the ground with cracks since faults are often formed in impact craters on Earth. One could guess that these ridge networks were dikes, but dikes would go more or less in the same direction, as compared to these ridges that have a large variety of orientations. Since the ridges occur in locations with clay, these formations could serve as a marker for clay which requires water for its formation. Water here could have supported past life in these locations. Clay may also preserve fossils or other traces of past life.
These ridges could be formed by large impacts that produced fractures, faults, or dikes made up of melted rock and/or crushed rock (breccia). One formation mechanism proposed by Quinn and Ehlmann in 2017 was that sediment was deposited and eventually the sediment underwent diagenesis which caused a loss of volume and fractures. After erosion exposed the fractures, they were filled with minerals possibly by acid-sulfate fluids. More erosion removed softer materials and left the more resistant ridges behind. If the impact-caused dike is made of purely melted rock from the heat of the impact, it is called a pseudotachylite .
Also, hydrothermalism may have been involved due to the heat generated during impacts. Strong evidence for hydrothermalism was reported by a team of researchers studying Auki Crater. This crater contains ridges that may have been produced after fractures formed with an impact. Using instruments on the Mars Reconnaissance Orbiter they found the minerals smectite, silica, zeolite, serpentine, carbonate, and chlorite that are common in impact-induced hydrothermal systems on Earth. Other evidence of post-impact hydrothermal systems on Mars from other scientists who studied other Martian craters.
Because ridges seem to be found in older crust only, it is believed that they occurred early in the history of Mars when there were more and larger asteroids striking the planet.
These early impacts may have caused the early crust to be full of interconnected channels.
These networks have been found many regions of Mars including in Arabia Terra (Arabia quadrangle), northern Meridiani Planum, Solis Planum, Noachis Terra (Noachis quadrangle), Atlantis Chaos, and Nepenthes Mensa (Mare Tyrrhenum quadrangle).
A somewhat different ridge formation has been discovered in the Eastern Medusae Fossae Formation; these dark ridges can be 50 meters in height and erode into dark boulders. It has been suggested that there are from lava filling fractures in the Medusae Fossae Formation which is surrounded by lava flows.
Linear ridge networks in Mare Tyrrhenum quadrangle.
Some of these may be from hydrothermal systems produced after an impact.


Marl Formation

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


Dekkas Formation

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


Underplating


Interval zone


Peace Valley Beds Formation

The Peace Valley Beds Formation is a geologic formation in California. It preserves fossils dating back to the Neogene period.


Honaker Trail Formation

The Honaker Trail Formation is a geologic formation in Utah. It preserves fossils dating back to the Carboniferous period.
It is a member of the 3-member Hermosa Group and is located above the Paradox Formation in the dramatic site of Goosenecks State Park, Utah, notably Cataract Canyon. It is gray-colored above the multi-layered Paradox deep in Cataract Canyon, riverside.


Hennessey Formation

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


William Ka Ming Lau

William Ka Ming Lau (born 22 March 1950) is a senior scientist at the Earth System Science Interdisciplinary Center, a research center at the University of Maryland and an Adjunct Professor of the Department of Atmospheric and Oceanic Sciences at the University of Maryland. A physicist by training, his research spans over 4 decades covering a wide range of topics in climate dynamics, tropical meteorology, ocean-atmosphere coupling, aerosol-water cycle interactions, and climate variability and change. Lau conducted pioneering research on atmospheric teleconnection, and the global monsoon climate system. He discovered the aerosol-monsoon regional feedback mechanism, i.e., the Elevated Heat Pump (EHP) effect that strongly modulate climate change in Asian monsoon regions. He was the senior author of a popular research reference book, “Intraseasonal Variability in the Atmosphere-Ocean Climate System”. As of November 2020, he has coauthored 297 refereed papers, with total citation = 33,932, h-index=101.
Education.
Lau was born in Macau, Special Administrative Region (SAR) China. He received his early education at a grade school run by the Jesuit China missions. In 1960, his family emigrated to Hong Kong, SAR, China, where he completed his high school education in New Method College. He received his BSc (Mathematics and Physics) in 1972; BSc Honors (Applied Mathematics) in 1973 from the University of Hong Kong; PhD in Atmospheric Sciences in 1977, from the University of Washington in Seattle, Washington.
Academic career.
After graduating from the University of Washington, he was recruited as assistant professor at the Naval Postgraduate School (1978-1980). In 1981, he joined the NASA Goddard Space Flight Center (GSFC) as a civil servant scientist. At GSFC, he rose through the ranks serving as the Head of the Climate and Radiation Branch (1991-2000), Chief of the Laboratory for Atmospheres (2001-2010), and the Deputy Director for Science, NASA Goddard Space Flight Center Earth Science Division (2011-2014). In 2015, he retired from GSFC, and joined ESSIC. Dr. Lau frequently visits international research and academic institutions around the world to present invited lectures, keynote presentations in scientific meetings, and public speeches to promote awareness on impacts of climate change on regional weather extremes. He has served on numerous national and international science steering groups, committees and review panels, including as Chair of Climate Variability (CLIVAR) monsoon panel, and member of the science steering group of Global Energy and Water Exchanges (GEWEX), World Climate Research Programme (WCRP). He was a coauthor of the chapter on regional effects of climate change of the Intergovernmental Panel on Climate Change (IPCC), and a U.S. National Academy of Sciences report on “Himalayan Glaciers: Climate Change, Water Resources and Security. In 2014-16, he served as the President of the Atmospheric Science Section of the American Geophysical Union
Awards and honors.
Lau has received many awards and honors for his research accomplishments and leadership, including:


Cow Head Group

The Cow Head Group is a geologic group in Newfoundland and Labrador. It preserves fossils dating back to the Ordovician period.


Soft-sediment deformation structures

Soft-sediment deformation structures develop at deposition or shortly after, during the first stages of the sediment's consolidation. This is because the sediments need to be "liquid-like" or unsolidified for the deformation to occur. These formations have also been put into a category called water-escape structures by Lowe (1975). The most common places for soft-sediment deformations to materialize are in deep water basins with turbidity currents, rivers, deltas, and shallow-marine areas with storm impacted conditions. This is because these environments have high deposition rates, which allows the sediments to pack loosely.


Manitou Limestone

The Manitou Limestone is a geologic formation in Colorado. It preserves fossils dating back to the Ordovician period.
Depositional Environment.
Because the rocks of the Manitou Dolomites are mostly indeterminate carbonates, the exact depositional environment is unknown. However it was likely shallow water, either lagoon or near-shore, and the many jumbled fossils of trilobite spines and brachiopods suggest that the paleoenvironment may have been prone to storms.
Paleontology.
The limestones and dolomites of the Manitou Formation, contain cast/mold-preserved Ordovician-aged marine fossils, including cystoid stems, brachiopods, and trilobites such as "Manitouella" ("Leiostegium"?) and "Kainella".


Virginia Toy

Virginia Toy (born 1979) is a New Zealand geologist who studies fault zones and earthquakes in New Zealand, Japan and Ecuador. She is one of the leaders of the Deep Fault Drilling Project of New Zealand's Alpine Fault, and was a research scientist on the Japan Trench Fast Drilling Project. She then worked as a Research Associate Professor in geology and Associate Dean (International) in the Division of Sciences at the University of Otago. Virginia currently works as a Professor at the University of Mainz.
Early life and education.
Toy grew up on Auckland's North Shore and gained her Bachelor of Science then Master of Science (with honours) in geology from Auckland University. She then gained a Master of Philosophy in Earth Sciences from the Australian National University and a Doctor of Philosophy in geology from the University of Otago in 2008. Her PhD was on the (micro)structural geology of New Zealand's Alpine Fault.
Career and impact.
In 2016 Toy was awarded a Rutherford Discovery Fellowship by the Royal Society for her research entitled: 'Weaving the Earth's Weak Seams: Manifestations and mechanical consequences of rock fabric evolution in active faults and shear zones'.
In 2017 Virginia Toy co-published in Nature that they had discovered "extreme" hydrothermal activity beneath Whataroa, a small township on the Alpine Fault, which "could be commercially very significant" and possibly globally unique.
Toy also worked on building stability during earthquakes in Ecuador, using computer modeling to determine the relationship between rock type and building damage. She has been used numerous times by New Zealand media as a geological expert, on the Kaikoura earthquake, tsunami risk, predicting the next earthquake on the Alpine Fault and the misreporting of science in the media. She has also been used as a popular science presenter in the book "Terrain: Travels Through a Deep Landscape" and TV show "Beneath New Zealand."


Drywood Formation

The Drywood Formation is a geologic formation in Missouri. It preserves fossils dating back to the Carboniferous period.


Amblydactylus

Amblydactylus is an ichnogenus that has been attributed to dinosaurs. The generic name, derived from the Greek words "amblys" and "dáktylos", means "dull finger". Two species of "Amlydactylus" have been named: "A. gethingi", which references the Gething Formation where it was found; and "A. kortmeyeri", which honours Carl Kortmeyer who discovered the holotype.
Large dinosaur tracks in the Winton Formation of Queensland, Australia, at the Lark Quarry trackway, were previously identified as cf. "Tyrannosauropus" and were as such interpreted as belonging to a large theropod. However, "Tyrannosauropus" has since been declared a "nomen dubium" and the referred tracks likely belonged to hadrosaurid ornithopods. Similarly, the large Lark Quarry footprints are also now suggested to belong to an ornithopod, and are most similar to "Amblydactylus gethingi", with the suggested referral of "Amblydactylus" cf. "gethingi".


Cerro Alto Limestone

The Cerro Alto Limestone is a geologic formation in Texas. It preserves fossils dating back to the Permian period.


Bermont Formation

The Bermont Formation is a geologic formation in Florida. It preserves mostly invertebrate fossils that date back to the Middle Pleistocene. Most of the fossils preserved are extant mollusk shells. It is mined commercially along with similar formations, to produce shell fill for construction.
A lot of our information on the Bermont Formation comes from commercial mining operations. Due to the nature of Florida's flat landscape, paleontologists rely on commercial interest in mining to gain access to otherwise inaccessible specimens for study. Such is the case with the Bermont Formation's bone bed in the Leisey shell pit.
As is the case with some other formations, UV can sometimes be used to bring out hidden pigmentation in some fossil shells. This is especially useful in telling the difference between some species, which would otherwise be indistinguishable.
Environment of Deposition.
The original environment of the deposits has been interpreted as being that of a shallow coastal marine reef, to open brackish waters, with a maximum depth of less than 15 meters. Currently, it is estimated that 10 - 20% of its mollusk species are extinct.
Index Taxa.
Index taxa in the Bermont formation currently include Strombus mayacensis, Vasum floridanum, Fusinus watermani, Fasciolaria okeechobeensis, and Miltha carmenae.


Petrogenetic grid

A petrogenetic grid is a geological phase diagram that connects the stability ranges or metastability ranges of metamorphic minerals or mineral assemblages to the conditions of metamorphism. Experimentally determined mineral or mineral-assemblage stability ranges are plotted as metamorphic reaction boundaries in a pressure–temperature cartesian coordinate system to produce a petrogenetic grid for a particular rock composition. The regions of overlap of the stability fields of minerals form equilibrium mineral assemblages used to determine the pressure–temperature conditions of metamorphism. This is particularly useful in geothermobarometry.
For example, suppose one came across a metapelitic rock containing chlorite, kaolinite, and quartz. As illustrated by the given petrogenetic grid on metapelites, one sees that such a rock can only form at relatively low pressures and temperatures. However, if it had carpholite instead of chlorite, then it would have formed at higher pressures, and if it had pyrophyllite instead of kaolinite, it would have formed at higher temperatures. This assumes the rock has a KFMASH composition, since that is what the experimental data was created with. If the composition of the rock differs from this, then the figure is less accurate.
Norman L. Bowen proposed the idea in 1940. At the time, he envisioned geologists eventually determining every possible metemorphic reaction and assembalge in nature, but realized that the magnitude of undertaking the necessary experiments was a huge task that would not be finished for a very long time. As such, modern petrogenetic grids are only partially complete. Depending on the level of precision and characterization needed, a petrogenetic grid may be simple, or it may be an extremely large system consisting of a hundred or more reactions.
To the right is an example of a rather complex petrogenetic grid for metamorphosed pelitic rocks. It shows most of the important reactions that govern the development of aluminous mineral assemblages from the prehnite-pumpellyite facies to the granulite facies, as well as the blueschist facies and eclogite facies at higher pressures and the contact hornfels facies at lower pressures. As the rock undergoes higher temperatures and pressures, one can see it follow the classic Barrovian sequence from the chlorite zone to the biotite zone to the garnet zone to the staurolite zone.


Mafic

A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian.
Chemically, mafic rocks are enriched in iron, magnesium and calcium and typically dark in color. In contrast, the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium. The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older "basic rock" class.
Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava. As a result, eruptions of volcanoes made of mafic lavas are less explosively violent than felsic-lava eruptions.


Boat Harbour Formation

The Boat Harbour Formation is a geologic formation in Newfoundland and Labrador. It preserves fossils dating back to the Ordovician period.


Pteraichnus

Pteraichnus is an ichnogenus that has been attributed to pterosaurs. It has been found in, among other units, the Lower Jurassic Aztec Sandstone and Lake Ezequiel Ramos Mexia in the Candeleros Formation.


Gregg Ranch Formation

The Gregg Ranch Formation is a geologic formation in California. It preserves fossils dating back to the Ordovician period.


Ancorichnus

Ancorichnus is an ichnogenus. Ancorichnus, is distinguished by structured mantle peripheral to a meniscate core. The mantle is not considered as a wall structure since it formed by the locomotive behaviour of the burrow producer. This ichnotaxon occurs in full relief at the top of grainstone beds 10 and 12. It is a non-branched, cylindrical, horizontal burrow with a diameter of 0.2-0.3 cm and 0.3-0.4 cm, respectively.


Planitia Descensus

Planitia Descensus was named to commemorate the site of the first soft landing on the Moon of Luna 9 on 3 February 1966. It is located at Lat. 7.1°N and Long. 64.4W. It is the only officially named plain on the Moon. The Working Group of Commission 17 of the IAU confirmed the name of the site in 1970.


Nathair Facula

Nathair Facula is a bright region on the surface of Mercury, located at 36° N, 295.5° W. It was named by the IAU in 2018. "Nathair" is the Irish word for snake.
In the center of the region is an irregular depression with crisp topography, surrounded by a region of subdued features. It is interpreted to be the site of explosive volcanic eruptions. Hollows have formed within the depression. The facula is approximately 270 km wide, although the edges are diffuse.
Nathair Facula is located northeast of the prominent Rachmaninoff crater, west of Copland crater, and east of the smaller Neidr Facula.


Bergisch Gladbach Formation

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


Chapin Formation

The Chapin Formation is a geologic formation in Iowa. It preserves fossils dating back to the Carboniferous period.


List of montes on Venus

This is a list of montes (mountains, singular "mons") on the planet Venus. Venusian mountains are all named after goddesses in the mythologies of various cultures, except for the Maxwell Montes.
The four main mountain ranges of Venus are named Akna Montes, Danu Montes, Freyja Montes, and Maxwell Montes. These are found on Ishtar Terra.
Mountain ranges are formed by the folding and buckling of a planet's crust. The mountain ranges of Venus, like those of the Earth, are characterized by many parallel folds and faults.
The presence of mountain ranges on Venus may provide evidence that the planet's surface is in motion.
Montes.
Key


Carmanah Formation

The Carmanah Formation is a geologic formation in British Columbia. It preserves fossils dating back to the Paleogene period.


Aber Mawr Formation

The Aber Mawr Formation is a geological formation in Wales. It preserves fossils dating back to the Arenig Series of the Ordovician period.


Adinath Lahiri

Adinath Lahiri (1916–1975) was an Indian geochemist and fuel technologist, known for his efforts in developing "Central Fuel Research Institute", Dhanbad (CFRI) into one of the premier research institutions in India. He was the director of the "National Coal Development Corporation" (NCDC) and contributed towards the establishment of the "Central Mining Research Station", which was later merged with CFRI to form the present day Central Institute of Mining and Fuel Research). The Government of India awarded him the fourth highest civilian honour of the Padma Shri in 1960 and followed it up with the third highest honour of the Padma Bhushan, in 1969, for his contributions to Science and Technology.
Biography.
Adinath Lahiri was born on 24 August 1916. After completing his master's degree in geology and geochemistry from the University of Calcutta, he obtained "Sir Palit Foreign Fellowship" of the university and did his doctoral studies at the Imperial College of the University of London to secure a PhD, winning the Judd Memorial Prize for the best thesis in geochemistry. He started his career as a research associate at the Department of Chemical Technology at Imperial College in 1942, but joined the Royal Air Force during World War II to serve as a Scientific Officer and, later, as the Head of the Fuel and Oil Research Section at the Royal Aircraft Establishment, Farnborough airfield. After the war was over, he returned to India, in 1945, to take up the position as the Assistant Director (Planning) at the Council of Scientific and Industrial Research (CSIR) when he contributed to the planning and establishment of the Central Fuel Research Institute (CFRI), Dhanbad. He joined the institute after its inception as the Deputy Director and when the founder director, J. W. Whitteker left, he took over as the director in 1953 to stay with the institute till his superannuation in 1974. In between, he also underwent training under a Summer Fellowship at the Massachusetts Institute of Technology School of Science in 1950. After his retirement from CFRI, he joined the United Nations as an advisor and served in Chile when he died on 26 August 1975, two days after his 60th birthday, succumbing to a cardiac arrest.
Lahiri's research interests covered the fields of petrography, oxidation mechanisms, solvent extraction, surface chemistry of coal, catalysts and adsorbents and he was credited with several innovations in fuel technology, which earned him over 90 patents. His contributions have been reported in the development of beehive coke oven, process technologies for the isolation and recovery of useful chemicals from the byproducts of coal, process technologies for the production of resins and other compounds, and active carbon and ion exchangers for determination of water-based coal. He published his research and professional experiences by way of over 500 articles, "Reaction of coals under plasma conditions: direct production of acetylene from coal", "National Coal Development Corporation A New Approach", and "Trekking on the Southern Bhutan Frontier" counting among them. During his tenure with CFRI, he proposed the setting up of "Central Mining Research Station" for overcoming the coal mining issues faced in India and served as the director of the National Coal Development Corporation. In 1954, he proposed energy studies, a pioneering effort in India, and served the Indian Energy Survey Committee of 1965 and the National Fuel Policy Committee of 1974, as a member.
Lahiri was an elected Fellow of the Institution of Engineers, Institute of Fuels (London) and the Indian National Science Academy (INSA), and served as a member of the INSA council from 1968 to 1970. In 1960, the Government of India awarded him the fourth highest civilian honour of the Padma Shri. Nine years later, he was included in the Republic Day Honours list again, this time for the third highest honour of the Padma Bhushan. "Central Fuel Research Institute", the institute he helped found, have since renamed their conferencing facility as "Adinath Lahiri Hall", in his honour.


Denbury Crinoidal Limestone

The Denbury Crinoidal Limestone is a geologic formation in England. It preserves fossils dating back to the Devonian period.


Traction (geology)

Traction is the geologic process whereby a current transports larger, heavier rocks by rolling or sliding them along the bottom. Thus, the grains and clasts interact with the substratum during transport. By contrast, saltation, a related sediment transport process, moves grains across the bottom by bouncing or hopping. The actual current carries the sediment load in traction and saltation flows, whereas downslope movement under the force of gravity carries the sediment in gravity flows. These processes contrast with suspension settling, in which there is no current.
Traction is where large stones or boulders in the river's load are rolled along by the force of the river.


Lincoln Creek Formation

The Lincoln Creek Formation is a geologic formation in Washington (state). It preserves fossils dating back to the Paleogene period.


Noachian epoch


Meeressande Formation

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


Lead Bell Shale

The Lead Bell Shale is a geologic formation in Idaho. It preserves fossils dating back to the Cambrian period.


Syed Mahmood Naqvi

Syed Mahmood Naqvi (28 August 1941—4 September 2009) was an Indian Earth scientist specialising in geochemistry at the National Geophysical Research Institute (NGRI) in Hyderabad. In a four-decade career, from the 1960s through 2000s, he was the recipient of numerous awards, scientific as well as humanitarian, and served as Fellow of the Association of Applied Geochemists, Indian Geophysical Union, Andhra Pradesh Academy of Sciences and Indian National Science Academy (INSA) as well as vice-president of the Geological Society of India, the Geological Mining and Metallurgical Society of India and the Indian Society of Applied Geochemists (ISAG).
Education.
A native of the town of Amroha in northwestern Uttar Pradesh, Syed Mahmood Naqvi received his school and university education in Amroha and Aligarh, and moved to Hyderabad in 1964, upon being appointed as a research scientist at NGRI on 9 November. Becoming a member of the Geochemistry group, he obtained his Ph.D in 1969/70, upon completing his thesis on the "structure, petrology, geochemistry, gravity field and tectonics of the central part of the Chitradurga Schist Belt, Dharwar Craton".
Professional career.
In his 39 years of active service with the NGRI, Mahmood Naqvi rose steadily through the cadre, serving as Acting Director of the institute from February to October 2001 and retiring with title of Scientist G in 2003. He remained loyal to the Council of Scientific and Industrial Research (CSIR) and did not leave it even when offered a professorship by his alma mater, Aligarh Muslim University (AMU).
In 1964, NGRI was mostly engaged in geophysical research, and Mahmood Naqvi was initially assigned to work with a team of geophysists, led by the eminent authority on mechanical engineering, M. N. Qureshi, in preparing a gravity map of India. However, he soon found his own niche. With the encouragement and support of NGRI director Hari Narain, as well as that of the head of his own division, Dr. Qureshi, Mahmood Naqvi initiated, as part of his Ph.D project, the first systematic geological/geochemical studies at NGRI. Upon receiving his doctorate from AMU in 1970 and, over the following 35 years, he continued to explore the Precambrian Geology of South India by generating and interpreting diverse geochemical data. Since NGRI, during the 1960s, did not have the facilities required for such high-level research, he applied his entire efforts towards funding and building at the institute state-of-the-art geochemistry laboratories which have continued to meet analytical needs of a large number of research organizations and universities in India. He also established linkages with some leading geochemists outside the country and, among many other projects, led, with John A. Rogers of the University of North Carolina, Chapel Hill, a highly praised Indo-US collaborative programme on Precambrians of South India.
Mahmood Naqvi contributed immensely to human resource development in geochemistry by guiding over two dozen Ph.D research students, most of whom have subsequently risen to occupy high positions in academic/research institutions and industry. Following superannuation in 2001, in his capacity as CSIR Emeritus as well as INSA Senior Scientist at NGRI, and despite failing health, he devoted his remaining years to research and authorship of several books, making this final period of his life one of his scientifically most productive.
Syed Mahmood Naqvi died in Hyderabad one week past his 68th birthday.
S.M. Naqvi Gold Medal was instituted in the name of outstanding scientist late Dr. S.M. Naqvi who contributed extensively in the field of Geology. He was associated with the Society in various capacities till his death in September 2009. Dr. S.M Naqvi Gold Medal will be awarded once in two years to a scientist below the age of 60 years for outstanding contributions in any field of Indian Geology.
Research achievements.
During a research career spanning nearly 45 years, Mahmood Naqvi made many outstanding contributions to earth sciences. These include:
Apart from catapulting the Dharwar Craton onto the canvas of global Precambrian terranes, Mahmood Naqvi's studies contributed new dimensions and leads toward unraveling several basic problems in Precambrian geology especially the relevance of uniformitarianism and paradigms such as plate tectonics to the early geologic history of the earth. He strongly advocated an early beginning of modern-style plate tectonics as far back in time as the Neo-Archean (2700 million years). He strived relentlessly to obtain critical evidences in the rock record of southern India to demonstrate his crust evolution model. His approach in this journey was holistic encompassing a range of earth processes involving interactions among atmosphere, hydrosphere and lithosphere in space and deep time.
References.
Life, education and family.


Pease River Group

The Pease River Group is a geologic group in Texas Red Beds. It preserves fossils dating back to the Permian period.


Cummingsville Formation

The Cummingsville Formation is a geologic formation in Iowa and Minnesota. It preserves fossils dating back to the Ordovician period.


Cedar Valley Formation

The Cedar Valley Formation is a geologic formation in Iowa. It preserves fossils dating back to the Devonian period. No type locality has ever been designated for this formation, but it is best known for limestone and dolomite exposures in and around Johnson County, Iowa. The formation is exposed in numerous road cuts, quarries and valley walls over much of north-east and north-central Iowa.


Parting lineation

Parting lineation (also known as current lineation or primary current lineation) is a subtle sedimentary structure in which sand grains are aligned in parallel lines or grooves on the surface of a body of sand (or lithified as a sandstone). The orientation of the lineation is used as a paleocurrent indicator, although the precise flow direction (i.e. upstream vs. downstream) is often indeterminable. They are also the primary indicator of the lower part of the upper flow regime bedform.
Description.
Parting lineation is a sedimentary structure commonly found on the surface of parallel-laminated sandstones. It is aligned with the current direction, the alignment holding out in places over several square meters. The lineation is formed by flat, parallel ridges which are separated by depressions or grooves. The height of the ridges rarely exceeds several grain diameters. In profile the depressions are flat-bottomed and the ridges are rounded. Ridges and depressions are arranged en echelon, so that in downstream direction the ridges pass into depressions and vice versa. The crosswise distance between individual ridges typically varies between 0.59 and 1.25 centimeters. Length as well as spacing of the ridges augments with increasing grain size: in fine-grained sands the ridges are 3.5 to 12 centimeters long, whereas in medium-grained sands they can reach 30 centimeters in length. The long dimension of the ridges is therefore 5 to 20 times their crosswise spacing. The coarse(r) sediment fraction accumulates in the ridges, whereas dark heavy minerals and mica trails take up an intermediate position between the ridges and the grooves.
Fabric.
Statistical studies of the spatial arrangement of the sand grains (fabric) show that in the horizontal plane the long axes of the grains form two symmetrical maxima oriented at an angle of 10 to 20 ° to the current direction. In the vertical plane these maxima are inclined at an angle of 8 to 10 ° into the current direction and the sand grains are imbricated.
Genesis of the structure.
It is meanwhile widely accepted that parting lineation forms in the turbulent, viscous boundary layer immediately above the sediment-water interface. Responsible for the shaping of the structures are streaky vortex trains within the boundary layer. Downcurrent these streaks start to gradually lift off from the sediment surface until they eventually “burst”. Whenever this happens fluid rushes in from both sides. This cyclic process of lift-off, bursting and inrush of fluid exerts a shear stress on the sediment surface, which ultimately finds its expression in the spatial arrangement of the sediment grains. After all it is this lateral inrush of fluid, which “sweeps up” the grains in the grooves and redeposits them in long parallel ridges underneath the lifting turbulences. This rhythmical process is known as "burst and sweep".
Mode of occurrence.
Parting lineation is restricted to coarse silts as well as to fine- and medium-grained sands (i. e. to grain sizes of 16 to 500 µ). The structure very rarely occurs in coarser sediments. Hydraulically it is characteristic for the lower part of the upper plane bed regime and results from fairly high current velocities of 0.6 to 1.3 meters per second.
Parting lineation forms in very different depositional environments. The structure is most commonly found on the beach where it forms in flat, wet sediments due to swash. Parting lineation can also be created in dewatering tidal channels. Geological formations like for instance the Old Red Sandstone or the Buntsandstein also give proof of the shallow marine character. Parting lineation has even been described from turbidites. Yet the structure is not only restricted to the marine environment, it can also form in river sediments, especially on point bars.
Parting-step lineation, which is characterized by step-like parting surfaces, has been reported by Banerjee from varves deposited in glacial lakes.
Parting lineation was even artificially reproduced in hydraulic experiments.
Remark: in the marine environment parting lineation doesn't have to be associated solely with the upper plane bed regime, it has been reported for instance from the erosive stoss side of ripple marks, megaripples and dunes. This implies that the structure can form already under lower current velocities.
Due to its varied and rather widespread occurrence parting lineation is not a unanimous indicator for depositional environments.
Theoretical considerations.
In order to derive an expression for the crosswise spacing of parting lineation it is useful to start with the quadratic stress law:
 τ = 1/8*f*ρ*Um2
The shear stress τ exerted by the current within the boundary layer is proportional to the square of the current velocity U. The Darcy-Weisbach friction coefficient f and the density of the fluid ρ are constants.
Empirical studies have found a dimensionless value Z = 100 for the parallel streaks/ridges. This can be equated to:
 Z = 100 = ρ/η*Ut*λ
where λ represents the measured spacing, Ut the shearing velocity and η the viscosity of the fluid.
We also have the following equality:
Ut = (τ/ρ)1/2 which yields after solving for τ:
τ = Ut2*ρ
After equating the two expressions for τ and some rearrangements one arrives at an expression for the crosswise spacing λ:
λ = 100*(η/ρ)*(8/Um2*f)1/2
By inserting the following realistic values one finds for λ:
η = 1.06*10−3 [Pa*s]
ρ = 1000 [kg/m3]
f = 0.01
Um = 1 [m/s]
λ = 100*1.06*10−6*(800)1/2 = 1.06*10−4*28.28
 λ = 2.998*10−3 [m]
The calculated crosswise spacing λ is 3 millimeters. This value is in fairly close agreement with the experimental values measured by Allen, which are nevertheless generally 2 to 4 times higher. The discrepancy can be explained by assuming that only strongly developed streaks leave a discernible ridge.
Conclusions.
Parting lineation is a very good indicator of the reigning current direction (and therefore also a good paleocurrent indicator). An analysis of the grain fabric furthermore leads to the determination the younging direction within the sedimentary succession. The lower part of the upper plane bed hydraulic regime of relatively swift currents is characterized by parting lineation.


Minnekahta Formation

The Minnekahta Formation is a geologic formation in Wyoming, United States. It preserves fossils dating back to the Permian period.


Lake Aymler Formation

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


Peter Killworth

Professor Peter D. Killworth (27 March 1946 – 28 January 2008) was an English scientist known for his work on oceanography and on the study of social networks. A prolific writer, he published more than 160 scientific papers over the course of his career. He was also known for his work as a pioneering author of text interactive fiction games during the early 1980s.
Peter Killworth died in 2008 from motor neurone disease.
Oceanography.
The major part of Peter Killworth's career was spent as an oceanographer, using applied mathematics to understand ocean dynamics. He had varied interests across the whole of physical oceanography, including the study of ice, polynyas, Rossby waves, instabilities and eddies. He completed his doctorate in "Numerical studies in Dynamical Oceanography" at Trinity College, Cambridge University in 1972. After a year conducting research in California, he returned to Cambridge to work with his former PhD supervisor, Adrian Gill and spent the next twelve years at the Department of Applied Mathematics and Theoretical Physics, the latter part of this being spent as a Research Fellow of Clare Hall College. He maintained close ties to the US during this period, including teaching at the Woods Hole Oceanographic Institution.
In 1985 he moved to Oxford to join the Robert Hooke Institute, also serving as a Research Fellow of Wolfson College, and later as a Fellow of St Cross College. In Oxford he "built and led a research team at the forefront of numerical ocean modelling". With the closure of the Institute, by then the NERC Oceanography Unit, he moved to Southampton in 1995 to build up a team at the Southampton Oceanography Centre, now the National Oceanography Centre, Southampton, focusing on ocean process modelling. During these years he established the journal "Ocean Modelling", which rapidly became one of the leading oceanographic journals, achieving the highest impact factor of any physical oceanographic journal in 2005.
Killworth's work was marked by several awards, including a Fellowship from the American Geophysical Union in 2000; the Fridtjof Nansen Medal from the European Geophysical Society in 2002; and the Stommel Research Medal from the American Meteorological Society in 2008 for his "many important contributions to ocean modelling and theoretical oceanography". After his death in 2008, the UK National Oceanography Centre established the "Peter Killworth Memorial Fund" to "provide an annual award to students to support their research, studies and professional development" and "to honour Peter's commitment to fostering and encouraging the careers of budding scientists."
Social networks.
Killworth was also known for his work on social networks, applying mathematical modelling to anthropological empirical research. His work in this area began in 1972, when he met American anthropologist H. Russell Bernard, whilst both men were working at the Scripps Institution of Oceanography in California. Bernard had been conducting research on an oceanographic ship, examining how different social actors interrelated and knew one another. Killworth proposed applying the 'Baltimore traffic problem algorithm' to the research challenges this presented. Over the next few years, the partnership would work extensively on the so-called "small world", examining differences in the answers to questions such as "how many people does the average person "think" they know?" and "how many people does the average person "really" know?"
Killworth's interest in social networks increasingly focused on answering challenging questions about issues on which responses from individuals in questionnaires could not be trusted or were unlikely to be reliable, and where direct empirical data was lacking – "apparently uncountable populations". He was keen to stress the practical implications of this sort of anthropology, highlighting that before "we decide how much money to spend on a social problem, we need to know how big the problem is. It may not matter to anyone but scientists whether the typical American knows 290 people or 2,900, but it matters a lot if we can tell whether populations like the homeless are increasing or decreasing." Killworth was proud of his modelling's contribution to accurately measuring key issues such as the real size of the HIV+ community, or the number of rape victims in given communities.
One academic outcome from this work was a challenge to Dunbar's number theorem. Dunbar's number theorem suggests a theoretical cognitive limit to the number of people with whom one can maintain stable social relationships. These are relationships in which an individual knows who each person is, and how each person relates to every other person. Dunbar's number is not derived from systematic observation of the number of relationships that people living in the contemporary world have. Killworth and his associates did a number of field studies in the United States that came up with an estimated mean number of ties – 290 – that is roughly double Dunbar's estimate. This was not an average of study averages or a theoretical hypothesis but a repeated finding. In 1997, Killworth and Bernard formed the keynote speakers at the International Network for Social Network Analysis annual "Sunbelt" meeting, presenting on this accumulated work.
Although perhaps best known for his work with Bernard, Killworth also conducted a range of work with social network researchers Chris McCarty, Gene Shelley and Gene Johnsen.
Software design.
During the late 1970s and early 1980s, the Department of Applied Mathematics and Theoretical Physics in Cambridge was the centre of much early interactive fiction text adventure software in the UK, using the Phoenix computer system there. Peter Killworth wrote the groundbreaking mainframe computer game "Brand X" with fellow mathematician Jonathan Mestel. With the software arm of Acorn Computers based just around the corner from his Cambridge department, it was not long before Acornsoft acquired the rights to "Brand X", which was released commercially for the BBC Micro computer as Philosopher's Quest. Other games followed, including Castle of Riddles, Countdown to Doom, Return to Doom and Last Days of Doom, the latter games released through Topologika. Killworth described these games as "unashamed puzzlefests, you can die in lots of (hopefully funny) ways – but undo will cure that – and it's very easy to get stuck." Killworth published a book on the writing and theory of text adventure games in 1984.
Killworth also turned his hand to other programming applications, and "worked on top RISC OS graph plotting program Tau after taking over the software from original author Tim Birks. He was also a frequent contributor to the ongoing design of the EasiWriter and TechWriter packages, published by Icon Technology.
Other interests.
Peter Killworth was also a keen amateur magician, and a member of the Cambridge University Pentacle Club for many years. He authored the "Paul Daniels' Magic Show" release under the Acornsoft Graphics brand for the BBC Micro computer in 1984, which provided a range of magical illusions to be conducted using early micro-computers.


Competence (geology)

In geology competence refers to the degree of resistance of rocks to deformation or flow. In mining 'competent rocks' are those in which an unsupported opening can be made.
Characteristics.
Competent rocks are more commonly exposed at outcrops as they tend to form upland areas and high cliffs or headlands, where present on a coastline. Incompetent rocks tend to form lowlands and are often poorly exposed at the surface. During deformation competent beds tend to deform elastically by either buckling or faulting/fracturing. Incompetent beds tend to deform more plastically, although it is the 'competence contrast' between different rocks that is most important in determining the types of structure that are formed. The relative competence of rocks may change with temperature, such as in metamorphosed limestones, which are relatively competent at low metamorphic grade but become highly incompetent at high metamorphic grade.
By rock type.
Unmetamorphosed or weakly metamorphosed sedimentary and volcanic rocks.
Most sedimentary and volcanic sequences show layering between different lithologies. When affected by deformation the response of the sequence depends on the competence of the various layers.
Metamorphic sequences.
Crystal plasticity starts to become more important as the temperature increases and, from low-grade metamorphic conditions upwards, the relative deformability of individual minerals begins to control the competence of particular rock units.


Flute Summit (British Columbia)

Flute Summit is a flat-topped summit in the Fitzsimmons Range of the Garibaldi Ranges of the Pacific Ranges in southwestern British Columbia, Canada. It is located on the north side of Cheakamus Lake just southeast of the town of Whistler in Garibaldi Provincial Park. The mountain is part of a group of hills called the Musical Bumps.
Geology.
In 2004, volcanologist Jack Souther of the Geological Survey of Canada convinced that Flute Summit is an exposed subvolcanic intrusion of an ancient volcano. Nearby mountains, such as Whistler Mountain and Piccolo Summit, consist of lava flows that were erupted from a volcano about 100 million years ago during the Late Cretaceous period. The subvolcanic rock that comprises Flute Summit is igneous rock that solidified inside the Late Cretaceous volcano. Subvolcanic rocks can remain semi-molten and hot for hundreds or thousands of years. Because the magma that forms subvolcanic rocks solidifies and crystallizes slower than magma erupted on the surface, mineral grains grow larger. This produces a coarse grained rock. As subvolcanic magma heats and sets up convention in nearby groundwater, a hydrothermal system is created. This hydrothermal system can form quartz veins like those found at Flute Summit, combined with sulfurous gasses released from the magma, cause chemical alteration of both the crystallizing subvolcanic intrusion and the neighbouring rocks. This is how Flute Summit got its red colour.


Slang Faculae

Slang Faculae is a bright region on the surface of Mercury, located at 24.5° N, 179.3° W. It was named by the IAU in 2018. "Slang" is the Afrikaans word for snake.
Slang Faculae lies on the southeast rim of the Caloris basin, east of Atget crater and south of March crater.


Metamorphic zone

In geology, a metamorphic zone is an area where, as a result of metamorphism, the same combination of minerals occur in the bedrock. These zones occur because most metamorphic minerals are only stable in certain intervals of temperature and pressure.
Concept.
The temperature and pressure at which the mineralogical composition of a rock equilibrated can vary laterally through a metamorphic terrane. The two parameters together determine the metamorphic grade. The difference in grade between two locations is called the metamorphic gradient. Planes that connect points with the same metamorphic grade are called isograds. The secant lines of isograds with the surface form lines on a geologic map.
Changes in mineralogical composition in a terrane reflect differences in metamorphic grade of the rocks. Minerals that are characteristic for a certain metamorphic grade are called index minerals. The first or last appearance of an index mineral (the place where a metamorphic reaction is observed) forms an easily recognizable isograd. A metamorphic zone is the region between two such easily recognizable isograds. Often they are named for the most characteristic index mineral of the zone.
Whether a certain index mineral occurs is also dependent on the composition of the rock itself. Many index minerals have complicated chemical compositions. If not all necessary elements are abundant, the mineral will not grow. When mapping the metamorphic grade of a terrane, a geologist has to take the lithology of the rock in account. Lithologies are mainly dependent on the protolith, the original rock before metamorphism. The main lithologies are ultramafic, mafic, felsic (or quartzo-feldspathic), pelitic and calcareous. In all of these (and other) lithologies, different combinations of minerals occur at a certain grade. The metamorphic zones in these lithologies can also be different.
Types of metamorphic zones.
The type of metamorphic zones in a terrane are also determined by the form of metamorphism. This is dependent on the geodynamic (tectonic and magmatic) setting in which metamorphism took place. The sequence of metamorphic zones is called a metamorphic facies series, and the most common of these is Barrovian (called after George Barrow who first mentioned it in 1912). In this series of zones, both pressure and temperature increase gradually along the metamorphic gradient. Barrovian metamorphism takes place during regional metamorphism, caused by crustal thickening in the roots of an orogenic belt (under mountain chains). Barrovian zones are especially easy to recognize in pelitic rocks. The prograde sequence of Barrovian zones is:
Often only part of the series can be found. Another metamorphic facies series is the Buchan series, that sees a fast increase in temperature but a relatively small increase in pressure. Characteristic minerals include andalusite, biotite and cordierite. The metamorphic prograde sequence of the Buchan zone series is:
biotite - cordierite - andalusite - sillimanite
Buchan metamorphism occurs often in extensional settings, for example at rift basins. In contact metamorphism (metamorphism caused by high temperatures at low pressure in the vicinity of an igneous intrusion) a local contact aureole of zones is formed around a heat source.
In rocks in subduction zones, that are transported to great depths in relatively low temperatures, rare types of metamorphic zones can develop. Two facies series are the Franciscan and Sanbagawa types. The rocks are characterized by prehnite-pumpellyite, blueschist or eclogite facies minerals.


Bed (geology)

Beds are the layers of sedimentary rocks that are distinctly different from overlying and underlying subsequent beds of different sedimentary rocks. Layers of beds are called strata. They are formed from sedimentary rocks being deposited on the Earth's solid surface over long periods of time. The strata are layered in the same order that they were deposited, permitting discrimination as to which beds are younger and which ones are older (the Law of Superposition). The structure of a bed is determined by its bedding plane, the surface that separates two layers. Beds can be differentiated in various ways, such as by particle size or rock or mineral type. The term is generally applied to sedimentary strata, but may also be used for volcanic flows or ash layers.
Types of beds include cross-beds and graded beds. Cross-beds, or "sets," are not layered horizontally and are formed by a combination of local deposition on the inclined surfaces of ripples or dunes, and local erosion. Graded beds show a gradual change in grain or clast sizes from one side of the bed to the other. A normal grading occurs where there are larger grain sizes on the older side, while an inverse grading occurs where there are smaller grain sizes on the older side. By determining the type of beds, geologists are able to determine the relative ages of the rocks.
Bed thickness.
A bed is the smallest lithostratigraphic unit, usually ranging in thickness from 1 cm to several meters, and distinguishable from the beds above and below it. A bedding layer is distinct to a lamina, which is commonly defined as a sedimentary layer with a thickness of less than 1 cm.
Engineering considerations.
In geotechnical engineering a bedding plane often forms a discontinuity that may have a large influence on the mechanical behaviour (strength, deformation, etc.) of soil and rock masses in tunnel, foundation, or slope construction.
Geologic principles.
There are geologic principles that the beds normally follow. Even though there can be cases where the principles do not apply mostly due to faults, they are true for most cases.


Sekwi Formation

The Sekwi Formation is a geologic formation in Northwest Territories, Canada. It preserves fossils dating back to the Cambrian period.
The formation principally comprises shallow water carbonates, but deepens to include mid-shelf mudstones, both calcareous and siliciclastic.


Hogshooter Formation

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


Hughley Shale

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


Planar deformation features

Planar deformation features, or PDFs, are optically recognizable microscopic features in grains of silicate minerals (usually quartz or feldspar), consisting of very narrow planes of glassy material arranged in parallel sets that have distinct orientations with respect to the grain's crystal structure.
PDFs are only produced by extreme shock compressions on the scale of meteor impacts. They are not found in volcanic environments. Their presence therefore is a primary criterion for recognizing that an impact event has occurred.


Alexandra Navrotsky

Alexandra Navrotsky (born 20 June 1943 in New York City) is a physical chemist in the field of nanogeoscience. She is an elected member of the United States National Academy of Sciences (NAS) and the American Philosophical Society (APS). She was a board member of the Earth Sciences and Resources division of the NAS from 1995 until 2000.
In 2005, she was awarded the Urey Medal, by the European Association of Geochemistry.
In 2006, she was awarded the Harry H. Hess Medal, by the American Geophysical Union.
She is currently the director of NEAT ORU (Nanomaterials in Environment, Agriculture, and Technology Organized Research Unit), a primary program in nanogeoscience. She is Distinguished Professor at University of California, Davis.
Early life and education.
She graduated from Bronx High School of Science in New York. She received B.S. (1963), M.S. (1964), and Ph.D. (1967) in physical chemistry from University of Chicago, where she studied with Professor Ole J. Kleppa.
Career and research.
In 1967, she went to Germany for postdoctoral work. She came back to the U.S. in 1968 and continued her postdoctoral work at Pennsylvania State University. Then she joined the Chemistry faculty at Arizona State University, for approximately five consecutive years. Later on, she moved to the Department of Geological and Geophysical Sciences at Princeton University in 1985. She became the chair of that department from 1988 to 1991. In 1997, she moved to University of California at Davis and became an Interdisciplinary Professor of Ceramic, Earth, and Environmental Materials Chemistry. In 2001, she was chosen as the Edward Roessler Chair in Mathematical and Physical Sciences. As of 2013, she was appointed interim dean of Mathematical and Physical Sciences in the College of Letters and Sciences, at University of California at Davis. Her specializations include: Solid-state chemistry, Ceramics, Physics and Chemistry of Minerals, Geochemistry.
Geochemistry.
Since 1997, she has built a unique high temperature calorimetry facility. She has also designed and enhanced the instrumentation. Navrotsky introduced and applied the method for measuring the energetics of crystalline oxides of glasses, amorphous, nanophase material, porous materials of hydrous phases and carbonates also more recently nitrides and oxynitrides. Obtaining the thermo chemical data is used to understand the compatibility and reactivity of materials in technological and geological application. The energetics provides insight into chemical bonding, order-disorder reactions, and phase transitions.
Navrotsky's calorimetry has also been used in providing thermo chemical data for a variety of perovskite-related phases which has major consequences for convection and evolution on a planetary scale.
One of Navrotsky's works has shown that many zeolitic and mesoporous phases have energies only slightly higher than those of their stable dense polymorphs. The energy is associated with the presence or absence of strained bond angles not with the density.
Nanomaterials.
Her research is mainly focused on the structure and the stability of both natural and synthetic nanomaterials along with their dependence of temperature and pressure. She is also looking into the application of nanomaterials in geochemical pollutant transport in the air as it relates to the global climate change.


Ernest Lundelius

Ernest L. Lundelius is a vertebrate paleontologist who has conducted research in the United States and Australia. Lundelius retired as professor emeritus at the Jackson School of Geosciences of the University of Texas. He was awarded a Fulbright Fellowship in the mid 1950s, the earliest part of his career, to undertake research on geologically recent vertebrate fauna in Western Australia, examining and describing fossils from the Pleistocene epoch and later. In 2008 Lundelius was distinguished by the Texas Academy of Sciences as their scientist of the year.


Bolast Formation

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


Idavada Volcanics

The Idavada Volcanics is a geologic formation in Idaho. It preserves fossils dating back to the Neogene period.


Atreipus

Atreipus is an ichnogenus or trace fossil attributed to early Ornithischian dinosaurs. Its significance for Triassic biostratigraphy has earned it some fame.
Reptile footprint faunules from the early Mesozoic Newark Supergroup of eastern North America.


Bad Cache Rapids Formation

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


Bryn Siltstone

The Bryn Siltstone is a geologic formation in Wales. It preserves fossils dating back to the Ordovician period.


Deseret Limestone

The Deseret Limestone, also known as the Pine Canyon Formation, is a geologic formation in Utah. It preserves marine fossils dating back to the Carboniferous period or Mississippian age. It was formed by the Panthalassa ocean around 340 Ma. Fossils are mostly of tabulate and rugose corals, and other marine invertebrates; vertebrates are represented by conodonts. The Deseret is a 500-foot thick layer of dolomitic limestone with chert, with a basal layer of black shale that is host rock for many Utah caves such as Timpanogos Cave National Monument.


Belden Shale

The Belden Shale is a geologic formation in Colorado. It preserves fossils dating back to the Carboniferous period.


Preble Formation

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


Kanosh Shale

The Kanosh Shale is a geologic formation in Utah. It preserves fossils dating back to the Ordovician period.


Erik Hauri

Erik Harold Hauri (April 25, 1966 – September 5, 2018) was an American geochemist at the Carnegie Institution for Science. He researched the movement of matter inside planets and how volatile compounds such as water originated on Earth and other planetary bodies, and their effects on volcanic systems.
Early life and education.
Hauri was born on April 25, 1966, in Waukegan, Illinois, and was raised in Richmond, Illinois. His mother, Karen, was a homemaker and his father, Lawrence, was an automotive mechanic. Lawrence was an enthusiastic fisherman who took Hauri on fishing trips, sparking a lifelong interest in the outdoors. Hauri had one brother and one sister.
Hauri attended Richmond-Burton Community High School. As the first in his family to attend college, he graduated with his B.S. from the University of Miami in 1988 with a double major in geology and marine science. He completed his Ph.D. at the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program in Oceanography in 1992.
Career.
Hauri worked as a postdoctoral investigator at the Woods Hole Oceanographic Institution and then assumed the position of staff scientist in the Department of Terrestrial Magnetism at the Carnegie Institution for Science in 1994. He also directed the Ion Microprobe Facility, where scientists can make micron-scale measurements of the isotopic and elemental composition of minerals.
In 1999, Hauri received the Houtermans Award from the European Association of Geochemistry. The following year he was awarded the James B. Macelwane Medal by the American Geophysical Union for significant contributions to the geophysical sciences by a young scientist of outstanding ability.
Since 2011, he served on the Executive Committee of the Deep Carbon Observatory and as co-chair of its Reservoirs and Fluxes Community. He was a member of the Geological Society of America, American Astronomical Society, and the American Association for the Advancement of Science, and was named a fellow of the American Geophysical Union and the Geochemical Society.
Research.
In his research, Hauri analyzed isotopes of different elements and uses modeling and seismic imaging techniques to understand the processes occurring inside the rocky planets and how these processes contributed to planetary evolution. One of these processes is volcanism. He studied how melting magma and eruptions impact the distribution of certain elements and volatile compounds inside of planets. In 2011, Hauri reported in "Science" that Moon sediments brought back on the "Apollo 17" mission contained 100 times more water than previously reported, suggesting that the Moon likely holds larger quantities of water than previously expected. Further studies of the isotopes in lunar water suggest that the water originated on Earth.
Personal life and death.
Hauri was married and had three children. He died of cancer on September 5, 2018, at his home in North Potomac, Maryland, aged 52.


Culm Measures

The Culm Measures are a thick sequence of geological strata originating during the Carboniferous Period that occur in south-west England, principally in Devon and Cornwall, now known as the Culm Supergroup. Its estimated thickness varies between 3600 m and 4750 m though intense folding complicates it at outcrop. They are so called because of the occasional presence in the Barnstaple–Hartland area of a soft, often lenticular, sooty coal, which is known in Devon as "culm". The word culm may be derived from the Old English word for coal "col" or from the Welsh word "cwlwm" meaning knot (due to the folding of the beds in which the coal is found).
Most of the succession consists of shales and thin sandstones, but there are also occurrences of slate, limestone and chert.
Culm grassland on the formation's slates and shales is composed of purple moor grass and rush pasture. It is noted for a wide diversity of species, some extremely rare including the marsh fritillary butterfly. Some 92 percent of Culm grassland has been lost in the past 100 years, 48 percent being lost between 1984 and 1991 alone. There are a number of organisations trying to halt the decline including Devon Wildlife Trust with its Culm Natural Networks project, Butterfly Conservation, and Natural England with its Environmental Stewardship Scheme.
Culm soils have traditionally been used for grazing as they are heavy to work and acidic.
Geological subdivisions of the Culm.
In the main Culm Basin and north Devon the succession is nowadays divided into an upper Holsworthy Group and an underlying Teign Valley Group (formerly and popularly, the 'Lower Culm'). By way of contrast, in south Devon the entire supergroup is represented by the Chudleigh Group. The Holsworthy Group is itself divided into an upper Bude Formation and a lower Crackington Formation though a Bideford Formation intervenes in the Bideford area. In the Launceston area the entire group is represented by the Bealsmill Formation. The Teign Valley Group is subdivided into numerous formations, two of the more significant of which are the Dowhills Mudstone and Teign Chert formations. The Chudleigh Group divides into an upper Ugbrooke Sandstone Formation and a lower Winstow Chert Formation.
National character area.
The Culm Measures give their name to The Culm national character area and natural area of England, a component of a landscape classification system co-ordinated by the public body Natural England. The Culm NCA covers a large part of north Devon, and contains 3,831 ha of the Dartmoor National Park, 9,009 ha of the North Devon Coast Area of Outstanding Natural Beauty (AONB) and 7,814 ha of the Cornwall AONB, as well as the North Devon Heritage Coast. The area is especially known for Culm grassland (nationally known as rhos pasture): species-rich pastures, typical of poorly drained acid soils, which support a suite of purple moor-grass and rush communities, forming a mosaic of vegetation communities with heathland, other species-rich grassland and wet woodland. This is a habitat unlike any other in England, which supports distinctive and often attractive plant species, including heath spotted-orchid, southern marsh-orchid, bogbean, and saw-wort; a number of characteristic butterflies, including the marbled white, and marsh, heath, silver-washed and high brown fritillaries; and a number of typical bird species including grasshopper warbler and willow tit, as well as breeding Eurasian curlew and reed bunting, and overwintering snipe and woodcock.


Dynamic quartz recrystallization

Quartz is the most abundant single mineral in the earth's crust (behind the feldspar group), and as such is present in a very large proportion of rocks both as primary crystals and as detrital grains in sedimentary and metamorphic rocks. Dynamic recrystallization is a process of crystal regrowth under conditions of stress and elevated temperature, commonly applied in the fields of metallurgy and materials science. Dynamic quartz recrystallization happens in a relatively predictable way with relation to temperature, and given its abundance quartz recrystallization can be used to easily determine relative temperature profiles, for example in orogenic belts or near intrusions.
Mechanisms of recrystallization.
Previous research has outlined several dislocation creep regimes present in experimental conditions. Two main mechanisms for altering grain boundaries have been defined. The first is the process by which quartz softens as temperature increases, providing a means for internal stress reduction by migration of dislocations in the crystal lattice, known as dislocation creep. These dislocations concentrate into walls, forming new grain boundaries. The other process involves differences in stored strain energy between neighboring grains, resulting in migration of existing grain boundaries. The extent to which these occur is a function of strain rate and temperature, those being, respectively, the factors controlling introduction of new dislocations and the ability of dislocations to migrate and form subgrain boundaries which themselves migrate.
Recrystallization regimes.
Observable microstructures in quartz can be classified into three semi-distinct groupings that form a continuum of dynamic recrystallization textures. These regimes will be discussed in terms of temperature changes, assuming a constant level of shear.
Bulging recrystallization.
The lowest temperature texture (~250-400°C), bulging recrystallization (BLG) is characterized by bulges and small recrystallized grains along grain boundaries and, to some extent, microcracks. The at-large proportion and structure of the original quartz crystals is preserved to the greatest extent, compared with the other profiles. Formed by a combination of the two mechanisms mentioned, limited crystal plasticity (due to low temperature) prevents any further separation of subgrains. It follows, then, that an increase in temperature results in an increase in recrystallized grain size and volume proportion (0-25%) as internal stress becomes more resolved.
Subgrain rotation recrystallization.
Following an increase in temperature, the dominant texture changes to one marked by the presence of distinct subgrains. Recognizable in thin section by a more polygonized texture, the increased softening of the quartz allows for more thorough reduction of internal stresses. Recrystallized grains show relatively straight grain boundaries and little to no intragranular deformation feature, such as undulose extinction or deformation lamellae. Volume proportion of recrystallized grains in this regime roughly ranges from 30-90%, forming subgrains not only in interstitial space, but also within larger crystals or ribbon grains. Subgrains and recrystallized grains are roughly equal in size and shape.
Grain boundary migration recrystallization.
The highest temperature of the three textures, grain boundary migration becomes the dominant mechanism at ~500-550°C. Exhibiting much larger recrystallized grain sizes than the other two regimes, in addition to lobate and highly interfingering boundaries, at these temperatures quartz is completely recrystallized. That is, no evidence for original grains can be found. At these high temperatures, grain boundaries are free to sweep across entire grains, resulting in much less localized boundary formation/change. In this case as well, intragranular deformation features have been erased, but may be present from later-stage overprinting.
Trends.
Aside from the obvious increase in temperature, there are other trends which arise in this progression of recrystallization.
Recrystallized volume proportion.
As mentioned above, with increased temperature there is a marked increase in the proportion of the rock having undergone recrystallization. From 0-30% in bulging recrystallization, up to 90% in subgrain rotation recrystallization and 100% in grain boundary migration, this property may be observed in quartzite, at least well enough to get relative temperature relationships in the field.
Recrystallized grain size.
Progressing from around 15 μm (bulging recrystallization) to about 85 μm (subgrain rotation recrystallization) to up to a few millimeters (grain boundary migration), this exponential increase is not only noticeable, but is part of the basis on which the three recrystallization regimes were demarcated.
Utility.
Observation of recrystallization in a rock sample can reveal a general temperature, but nothing very precise. This is because the process of recrystallization is strongly affected by the presence of water and the amount of strain present. As such, this information can be applied to determine relative temperatures of different rock much more reliably than it can determine absolute temperatures. Furthermore, this is an analysis that can be done, if only preliminarily, in the field by observing rocks in hand sample.


Hope Shale

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


Micrographic texture

In petrology, micrographic texture is a fine-grained intergrowth of quartz and alkali feldspar, interpreted as the last product of crystallization in some igneous rocks which contain high or moderately high percentages of silica. "Micropegmatite" is an outmoded terminology for micrographic texture.
This fine-grained texture is similar to the coarser intergrowths in certain pegmatites and coarse granitic veins; the quartz forms angular patches scattered through a matrix of feldspar. In polarized light the separate areas of each mineral extinguish at the same time, and this proves that, even though apparently discontinuous, they have the same crystalline orientation.
The feldspar may be considered an irregular crystal of spongy structure, the interstices being filled up by another spongy crystal of quartz. Some of the coarser-grained examples are said to be "graphic", because the intergrowths vaguely resemble ancient cuneiform lettering. Some micrographic intergrowths are similar to those characteristic of granophyre.
Micrographic differs from graphic granite in being so much finer-grained that the texture can only be seen in a petrographic thin section with a microscope. The feldspar is usually orthoclase, but can also be albite, oligoclase or microcline. In at least some instances, quartz is so disposed that the two minerals have a definite relation between their crystallographic axes.
In rocks where micrographic texture is most common, it is usually interpreted as the last product of crystallization, and may represent residual melt. Commonly it has no definite form of its own, but fills up the irregular interspaces between the earlier crystallized minerals. The compositions of these residual crystallization products may represent eutectic compositions, the mixtures (quartz plus feldspar plus minor amounts of other minerals) which have the lowest fusion point. The texture may commonly form in the presence of a vapor phase as well as a silicate melt, however, and vapor-rock reactions below the solidus may result in feldspar replacement and consequent compositional changes.
The texture should not be confused with myrmekite or granophyre, in which quartz forms club-shaped, curved or vermiform threads intergrown with plagioclase feldspar and alkali feldspar, respectively.
In some rocks the whole groundmass consists of spherulitic growths of fibrous quartz and feldspar; in their centres there is often a quartz or feldspar crystal; the outer boundaries of the spherulites are not usually circular but irregular, owing to the interlocking of adjacent spherulites at their margins. Such textures may document solid-state devitrification of glass.


Foraker Formation

The Foraker Formation (or Foraker Limestone) is a geologic formation in Nebraska, Kansas, and Oklahoma. It preserves fossils dating to the Carboniferous period.


Bluestone Formation

The Bluestone Formation is a geologic formation in West Virginia. It is the youngest unit of the Upper Mississippian-age Mauch Chunk Group. A pronounced unconformity separates the upper boundary of the Bluestone Formation from sandstones of the overlying Pennsylvanian-age Pocahontas Formation.
Two formally named subunits of the Bluestone Formation, the Bramwell and Pride Shale Members, are quite fossiliferous. Plant fossils allow the top of the Bluestone Formation to be correlated with the Namurian A-Namurian B boundary, the European equivalent of the Mississippian-Pennsylvanian boundary. Conodonts belonging to the "Adetognathus unicornis" or lower "Rhachistognathus muricatus" conodont zones have been found in the Bramwell Member. This would make the Bluestone Formation the youngest occurrence of Mississippian-type conodonts in eastern North America. A diverse bivalve fauna was present in both the Bluestone Formation and the older Hinton Formation. Brachiopods were also fairly diverse, though not as dominant in the ecosystem as bivalves. Among the most abundant fossils were fossilized tubes of "Microconchus hintonensis", a microconchid. The Pride Shale Member has produced "Tanypterichthys pridensis", an endemic species of deep-bodied palaeonisciform fish.
The Pride Shale Member of the Bluestone Formation preserves interbedded variations in sediment coarseness. This variation is cyclical at multiple scales, with cycles from smaller than a millimeter to up to several meters in thickness. The smallest-scale cycles likely represent sediments settling out during daily tides. The largest-scale cycles are tied to changes in the tides influenced by the 18.6-year lunar nodal cycle. Cycles are also observed at half-year, monthly, and half-month scales. These correspond to seasonal changes, perigee/apogee tidal variation, and neap/spring tidal variation, respectively. Together, the different cycles reconstruct a deltaic environment near the equator which was heavily influenced by tides and a monsoonal climate. Modern equivalents would be the deltas of the Amazon, Ganges/Brahmaputra, and Fly rivers. During glacial periods, the monsoonal climate would have mellowed out into a less seasonal tropical climate in equatorial regions.


Tilcarian unconformity


Impletosphaeridium elegans

Impletosphaeridium elegans is an extinct species of dinoflagellates in the order Gonyaulacales. It is from the Early Tertiary.


Churchill River Formation

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


Oncolite

Oncolites are sedimentary structures composed of oncoids, which are layered structures formed by cyanobacterial growth. Oncolites are very similar to stromatolites, but, instead of forming columns, they form approximately spherical structures. The oncoids often form around a central nucleus, such as a shell fragment, and a calcium carbonate structure is deposited by encrusting microbes. Oncolites are indicators of warm waters in the photic zone, but are also known in contemporary freshwater environments. These structures rarely exceed 10 cm in diameter.
The appearance of recent/subrecent freshwater oncoids has been documented in two rivers in Bavaria: the Alz, whose source is the Chiemsee, and the Moosach, near Freising.
Oncolites may have either a porostromate or spongiostromate texture. Most oncolites are spongiostromate, having no recognisable cellular texture or microstructure. Porostromate oncolites are mostly unknown during the Precambrian; since the Eocene they have mostly been confined to freshwater environments.


Pittsburg Bluff Formation

The Pittsburg Bluff Formation is a geologic formation in Oregon. It preserves fossils dating back to the Paleogene period.


Haybes Formation

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