The first month on Cat Ba Island – getting my bearings

My apologies for the long gap between posts, life has been a bit busy.

I recently began a new position in Vietnam, on Cat Ba Island to be specific.  My first impressions are that this is a damp and precipitous landscape.  I have not seen the sun since I arrived in Vietnam on March 4th.  For Cat Ba Island this means a riotous profusion of greenery tempered by the steep terrain and lack of soil.

Where the northern end of the road terminates

Where the northern end of the road terminates

This is a land where Ymir’s bones lie close to the surface, broken and weathered, their calcium leaking back into the waters from which these precipitous cliffs rise.  The geology is the first thing that strikes you here.  The cliffs have been weathered by millions of years of rain, the ever-so-slightly acid rainwater eating into the ancient limestone creating a mature karst landscape.  Like bones, coral, and seashells, limestone is primarily made up of calcium carbonate, which in other forms makes marble and dolomite.  This is probably one of the reasons this is a place where snail diversity is immense, ranging from tiny frilled creatures more akin to limpets to giant land snails, many of which are still unknown to science.  Snails need lots of calcium to make their shells.

Unknown frill terrestrial snail

Unknown frilly terrestrial snail

Land snail shells collected around the office - and a wasp nest

Land snail shells collected around the office – and a wasp nest

The banded limestone found here is a relic of abundant diatom (a type of plankton) skeletons laid down five hundred million yeas ago and subjected to the vagaries of time.  Limestone, while soft to the chisel and hammer, is a remarkably durable stone at the macro-scale, one of the reasons climbers like it, but at a chemical level it is easily weathered.  We are often told that water has a pH of 7, that is it neutral.  Natural rainwater, we then assume, should also have a pH of 7, but it is closer to 5.6 due to the dissolution of carbon dioxide into the water making carbonic acid.  A pH of 5.6 is about as acidic as a cucumber or an onion for comparison.  Of course, other environmental factors can reduce this tremendously, leading to extremely acidic rain.  Rain falling on the limestone erodes small channels in the rock that look like thumbprints in wet clay.

Rainwater erosion on limestone

Rainwater erosion on limestone

Eventually these concentrate water flow, carving small holes in the stone reducing it to a swiss-cheese like structure with an extremely jagged and sharp exposed surface.  These little caves connect into larger caves.  In these protected, damp environments bacteria grow, exuding waste products and creating hydrogen sulfide that mixes with the water and makes a weak sulfuric acid, increasing the chemical weathering.  This cycle persists, eventually leading to enormous caves.

The airflow in these caves evaporates the mineral rich water tricking through the now porous stone and the calcium carbonate re-solidifies into stalagmites, stalactites, soda straws, and any number of strangely beautiful and complex cave structures.

Caves often form in weak portions of the stone and, eventually, gravity takes its toll and the weakened rocks collapse leaving behind steep spires and fields of slowly eroding boulders.

Limestone spi

Limestone spire in the north end of Cat Ba Island

Cat Ba and Ha Long Bay are examples of a drowned karst landscape, a mature karst landscape that has been flooded by rising waters.  What little soil does form is washed down into the many bays, coves, and channels of the region, leaving little for plants to sink roots into.  In the shallow waters of the bays mangroves find nutrients, in abundance.  Here mangroves are near the northern margin of their range, their numbers restricted and the trees short, making low dense forests.

Gray mangroves on the south western side of the island

Gray mangroves (Avicennia marina) on the south western side of the island

As in many places, the mangroves are in trouble here, often cut down to make shrimp farms.  This leads to reduction in local fisheries, increased erosion, and lack of protection from storm surges and tsunamis.  The local government is taking steps to protect what remains and to, potentially, restore some of the previous mangrove forests.  In the rich mud of the mangrove regions there are numerous animals, among them one of my favorites, mudskippers, amphibious fish that hop about in the mud protecting their little territories.

Mudskipper amongst mangrove roots

Mudskipper amongst mangrove roots

On the cliffs however there are few nutrients and plants grow in what cracks and declivities they can find.  As per many islands there are a number of endemic species, here one of the most commonly seen ones is the Ha Long Cycad (Cycas tropophylla), an ancient type of gymnosperm that looks like a cross between a fern and a palm tree.

Ha Long Cycad (Cycas tropophylla), endemic to a 400km square area, globally rare, locally abundant

Ha Long Cycad (Cycas tropophylla), endemic to a 400 square km area, globally rare, locally abundant

The season here is shifting into spring and some of the trees have begun blooming, among them the hoa gạo or Cotton Tree (Bombax ceiba), so named for the kapok-like fibers that are found in the seed pod.

Hoa Gạo (Bombax ceiba), Cotton Tree in English.  The Vietnamese name translates to "Rice Flower"

Hoa Gạo (Bombax ceiba), Cotton Tree in English. The Vietnamese name translates to “Rice Flower”


I still have not seen the little primates I came here to work with, they are few in number and they clamber about on the vertical cliffs like, well, monkeys.

Soon though.


Segovia: sandstones and granite

I have always loved things made of stone, especially ancient constructions.  The stone-masonry I have done has only increased my respect for the strength, vision, and talent of past masons.

Vermont garden wall

Small garden wall of Panton Shale for a friend in Vermont

Most of my stone projects have been small in scale.  The largest project was a 180 foot long retaining wall standing between 2 and 6 feet high, using 30 or 40 tons of stone.  That seems large when you’re doing it by yourself, but that’s a tiny project, barely larger than the little garden wall in the photo above.

In Peru there were some truly astounding pieces of megalithic engineering, many of them little known like Lanche and Kuelap, others well known like Saqsaywaman.

Walls at Saqsaywaman.  For scale zoom into the center of the full-size image to see the person.


Two days ago I went to the small Spanish city of Segovia and got to see several astounding pieces of stone-based architecture.  The first of these is the ancient Roman aqueduct.

The aqueduct in Segovia

The aqueduct in Segovia

The aqueduct runs about 15 km from the mountains into Segovia, with a 683 meter long raised section running through town.  The tall double arch of granite blocks is impressive enough by modern standards, even more so when you consider that it was built in the 1st or 2nd century, that the granite had to be carried in from the mountains, and that it is a dry-laid structure (no morter holding the blocks together) that has been standing for 1800 or 1900 years.  Clearly, this is a place with few earthquakes.

Granite is a favorite building material for many people.  It is an igneous rock that bubbles up in volcanic flows and cools in place.  The size of the crystals in the rock give an estimation of how long it took for the rock to cool and how much water there was in the melt.  The colors tell of the mineral content.  This granite is pale, with moderately large crystals weathering out, leaving the exposed stone extremely rough to the touch.

Due to the way it forms granite has no preferential cleavage plane, meaning that, given the right tools, it is easy to shape into whatever form is needed.  It is a dense and strong rock as well, another reason it is often used as a foundational material.

The blocks of stone making up the aqueduct are large, not enormous, but large, hundreds of pounds each.  At its highest point the aqueduct is 29 meters tall (that’s about as tall as a 4 or 5 story building).  Nearly 2 thousand years ago those blocks had to be hoisted up and set in place.  Clues as to how the Romans did so are carved into the blocks.

Lifting divots on the granite blocks

Lifting divots on the granite blocks

Each block was lifted into place with a pair of metal pincers, like those people used to carry ice-blocks with.  Divots were carved into the stone to prevent the pincers from losing their grip.  Presumably the divots were carved at the balance point of the block as well, a calculation I would be very curious to know how was done.

Supposedly Segovia was a “small outpost” when the Romans ran things in the area, though the effort and cost of building the aqueduct makes me question that assessment.  Small outpost or no, very little happened in the area for a long while, then in the 1200s the town began to grow and with that growth came the buildings that Europe is so well known for.

Castles and Cathedrals.  Segovia has impressive examples of both, the castle being the inspiration for Walt Disney’s version of Sleeping Beauty, and the cathedral being on the of the last of built of the great Gothic cathedrals.

Segovia cathedral

Segovia cathedral

Construction of the cathedral began in the 1500s, but took more than a century to complete.  The massive building looms over the city, glowing golden in the sunlight.

The first thing that struck me was neither the size nor the the tremendous amount of fine detail.  It was the color.  A warm, yellow/orange, not the color one associates with Gothic architecture, or with goths in general.  The castle, cathedral, and much of the rest of Segovia is made from this stone, not from the granite the aqueduct is made from.

The town of Segovia rests upon an outcrop of calcareous sandstone (sandstone with the grains cemented together by calcium rather than silica) and the land around rises and falls, exposing the bedrock in numerous small cliffs.  Sandstone is a sedimentary rock, a class of rock at the opposite end of the formation spectrum as granites and other igneous rocks.

Sandstone tends to have horizontal cleavage planes, refection the initial depositional patterns, and is often soft and easy to carve.  The sandstone in Segovia seems made for carving and the cathedral  builders took full advantage of this.

Cathedral detail carved from sandstone

Cathedral detail carved from sandstone

Sandstone weathers and erodes easily, especially in the presence of water.  Segovia, despite being a dry region by my standards (about a half meter of rain per year) is considered a wet place in comparison with nearby areas.  As such the builders took pains to protect the soft sandstone, making their waterspout gargoyles of the more resistant granite.

Cathedral gargoyle rain-spout

Cathedral gargoyle rain-spout

Statues of sandstone have not weathered as well as those of granite.

A royal lion slowly weathering away

A royal lion slowly weathering away

The the level of fine detail in the cathedral architecture is reflected elsewhere in the town.  The older buildings and the castle are covered with patterned façades.  In the past these patterns seem to have indicated which family owned the building and in a few cases older patterns could be seen under the more recent ones.

Old wall pattern, the material looks and feels like reconstituted sandstone.


The castle, the Alcázar de Segovia, has a more simple pattern, but each intersection is studded with fragments of volcanic rock.

Looking up the castle wall to the battlements.  the small black studs are fig sized pieces of vesicular volcanic rock brought in from far away.


Like many European castles the one at Segovia has gone through a number of iterations; fort, castle, palace, prison, artillery college, and museum.  It still serves the latter two roles.

The castle commands a wonderful view of the countryside in all directions.  One of the most magnificent views is of the cathedral:

Segovia cathedral from atop the Alcázar de Segovia battlements

Segovia cathedral from atop the Alcázar de Segovia battlements

In the opposite direction an old Templar keep and the sandstone cliffs much of the stone was quarried from to make the city are visible.

Templar keep and sandstone cliffs above the river below the castle

Templar keep and sandstone cliffs above the river below the castle

This has been a less science based post than most, but the trip to Segovia was far too interesting to keep all to myself.

The castle, aqueduct, and cathedral are the largest of the attractions, but not the only ones by far.  The food is delicious, mockingbirds flit about the city, interesting small plants grow from the old walls and on the red tile roofs, and great architecture abounds.

Small church in Segovia

Small church in Segovia

The Frontenac Arch a Critical Linkage

(this is an article I wrote for the summer 2012 newsletter of A2A – Algonquin To Adirondacks Conservation Association – a bi-national conservation association I am an adviser for – I wanted to wait until it was included in the newsletter before posting it here as well)

Between the Algonquin and the St. Lawrence a finger of the Canadian Shield, called the Frontenac Arch, reaches down from the north.  The Canadian Shield is an ancient formation of rock, heavily weathered, marked with meteor craters, and bearing the polishing scars of the ebb and flow of glaciers miles deep. Soils are shallow on the Shield, in many places nonexistent.  Nutrients are hard to come by and wetlands abound.

Red-winged Blackbird (Agelaius phoeniceus)

The bedrock to the east and west of the Frontenac Arch is old seafloor with thicker soils that are rich in minerals and nutrients. Groundwater flows through breaks in the flat bedding planes and does not become trapped in pockets as easily as it does on the Canadian Shield.

When we look at a landscape we often look at the plants growing on the surface and leave our thoughts on the surface with them.  Plants grow where they do because of the chemistry of bedrock, soil, water, and temperature.

On the Frontenac Arch the chemistry of the northern and the southern Canadian forests mix.  This mix shows in the wide and unusual range of plants growing in and around the Frontenac Arch.  The diversity of plants attracts a corresponding diversity in animals. All these plant communities are separated and connected by the dense wetlands, and many animals are drawn to the wetlands.  Frogs, fish, ospreys, turtles, feeding moose, waterfowl of all sorts, beavers, blackbirds, otters, sparrows, loons, and many more.

Male Painted Turtle (Chrysemys picta)

Healthy wetlands are rich in species, both in number and diversity; plant, animal, insect, and bird.  Wetlands are the kidneys of the planet; they filter water and keep it clean.  They slowly recharge aquifers with cool, pure water, they keep rivers and streams clear, they trap sediment, and they eventually fill in, becoming rich, complex soils full of nutrients.

Oddly, perhaps counter intuitively, all this life, more specifically all this diversity, of living things in wetlands is what keeps the water clean.  The water is strained at a molecular level for nutrients by all those living organisms.  Each looks for different things and uses them differently.  Toxins and chemicals are swept up and broken down by this process, but only as long as the diversity of life is present.

When that fabric of diversity is broken the health of the land suffers.  A healthy environment is like good glass, so clear you don’t see it and tough enough to withstand storms.

A large male Snapping Turtle (Chelydra serpentina) and feral biologists

The Frontenac Arch is one of the gems of the region and is critical in connecting the northern and southern forests.

*          *     *     *          *

For those who are interested the Algonquin to Adirondacks Conservation Association website is here, and a map is below:

Algonquin to Adirondacks Conservation Association map of the Frontenac Arch

Meteor Impacts and Ourselves

I am fascinated and enthralled by things that fall from space and the marks they leave behind.  It’s not just my love of space, it’s is something far more profound, it is in part what those things signify.

Go to a museum, one that has meteorites.  Often there will be at least one display of a metallic body that you can touch.  Lay your hands on it, press your palms against it, feel the soft curves, the slightly nubby surface, the coolness of the blackened metal.  You are touching the core of an extinct planet.  That should give you pause and send a small shiver up your spine.

On Earth there less than 200 known, confirmed, impact structures.  Just looking at the map it is clear that the distribution is skewed to areas where there are many people (North America & Europe), exposed bedrock (Canada & Scandinavia), or regions where weathering is slow (Australia & North Africa).

Confirmed impact structures on Earth from:

Every other rocky body in the solar system is liberally coated in the scars left by impacts.  The Earth bears the history of its impacts in a different way.  Weathering, plate tectonics, and the oceans have served to hide the marks of the numerous past impacts.  Except…

The global ocean, that covers 70% of the surface of the planet to a depth of 7 miles in some places, this, the single largest surface feature of the planet, is impact derived.  It is believed that ALL the water on the planet arrived by cometary impacts soon after the planet formed.  The Moon is another large impact structure, a relict left over from  the collision of the proto-Earth and another roughly Mars sized body.

The frequency of large impacts has, thankfully, fallen over time, but they still happen.  Some of you, I hope all of you, may remember the comet Shoemaker-Levy 9, the comet that crashed into Jupiter in 1994 after being torn apart by Jupiter’s immense gravitational field.  The fireballs in Jupiter’s atmosphere were larger than the entire Earth, and there were multiple fireballs.

Shoemaker-Levy 9 impact on Jupiter

The energy released by each of the Shoemaker-Levy impacts was on a par with the Chicxulub impact in the northern Yucatan 65 million years ago that is implicated in the demist of all terrestrial animals larger than a piece of carry-on luggage.

On Earth impacts are still frequent, but most are small and do not survive passage through the atmosphere.  Think shooting stars, grains of sand and dust traveling at orbital speeds, around 20km/second.  Several months ago, on the last day of February, I was treated to a something more dramatic than one of these little grains of dust.  A little after 10pm on the 28th I was driving under a clear sky and the snow covered landscape lit-up with a bright blue flash.  I later found out that the flash of light had been seen from New Jersey to Quebec.  This was just one of the many fireballs that flash in the sky each year, probably something small only a few meters in diameter, an explosion not more than a few kilotons.

In a few places the scars left on the ground from large impacts are still visible.  One of my favorite ones is in NE Canada.  Canada is an excellent place for finding impact structures as much of the Canadian Shield is ancient, exposed bedrock.

Manicoaguan impact crater turned into a reservoir

The Manicoaguan impact is about 215 million years old and approximately 60 miles across.  It has been dammed and the island in the middle is now one of the largest fresh-water islands in the world.  Big impacts like this are rare, but they leave dramatic remains behind.

Small impacts are surprisingly common, the frequency rapidly trailing off the larger the impact.  This is good news, but the picture is very incomplete as we have only been able to watch carefully for a short period of time.

Impact frequency Table from

We are struggling to understand how the universe fits together and have tremendous difficulty comprehending the scales and energy involved.  We are too used to thinking on our small scales, our bodies, our houses, maybe our planet, for a few our solar system or galaxy.  Our solar system is huge, our galaxy immense, yet in the lager context of our body of knowledge and what we can see even the Milky Way galaxy is barely a microscopic speck.

Look at the ocean, lay back and watch the trails left by falling meteors, look at the background of stars, go to a museum and touch the heart of a planet, if you live near an impact crater go visit.

We often say, “We are all connected,” and this is true, and that web of connection is far greater, wider, and deeper than most of us realize.

What is Nature?

For most of my life I have been immersed in the natural world.  My early memories are of mud, water, ferns, tide-pools, insects, birds, amphibians, and trees to climb.  Nature surrounds us, enfolds us, and directs our lives in ways we often fail to realize.

Despite our reliance on computers, cars, oil, and all the rest, and the damage our irresponsible use of these things has done to our planet and ourselves, these things all derive from nature.  The location of oil deposits are a relic of past distributions of plant and microbial life. Distribution of plants, animals, and other resources such as iron, gold, and bauxite deposits are a product of geology, which in turn is a result of solar system formation.  At each step we can look a little further back and deeper into the picture and see more of nature and how it affects us physically and socially.

Gold comes from supernovae, thus, indirectly, the Spanish conquering of Central and South America was, in part, due to the interaction of gravity, nuclear fusion, and the age of the universe.  Stars that become supernova are a result of the specific balance of elementary forces in our universe.

Tools are made in the shapes they are due to the evolutionary forces that shaped our bodies, which in turn are a result of the same elementary forces that lead to supernovae and the creation of gold.  Toast more often lands butter-side down because of the height of our tables.  The height of our tables is determined by our height, which is limited by the physical constraints imposed by the molecular bonds that hold the component pieces of our bodies together under the influence of one standard Earth gravity.  Toast falls butter-side down because of the strength of our bones.

This is nature, just as much as the metamorphosis of a caterpillar to a Monarch butterfly, and the many thousand mile migration of those butterflies to a forest in northern Mexico.

There is not just a whole world to explore, there is a whole universe to explore, perhaps more than one.  In this blog I intend to explore those bits I can reach, physically or mentally.

I hope you enjoy what emerges on these pages.

Bristol Pond, Vermont