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.

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.

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.

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

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The Mighty Dragonfly

Of all insects there are few that capture our attention and interest the way dragonflies do.  They have, perhaps, the coolest, most evocative name of any group of insects: Dragonfly.  In English there are a great number of other common categorical names: Devil’s Darning Needle, Snake Doctor, and Ear Cutter among others.  Many of these names come from the mystifying apparent fear of nature that crops up over and over in European views of the world.  Many European cultures viewed dragonflies as sinister creatures, servants of the devil, in league with other evils such as snakes and bats.

Other cultures, often more agrarian ones, had a far more benign view of dragonflies, based, perhaps, on the recognition of their fundamental role in controlling populations of pest insects of all sorts.  An archaic name for the Japanese Islands is Akitsushima (秋津島), the Dragonfly Islands, where dragonflies symbolized courage, strength, and happiness.  For some native American tribes dragonflies symbolized clean, pure water, swiftness, and agility.  In the modern world dragonflies are good indicators of environmental heath, indicating a robustly functioning ecosystem.

Libellula quadrimaculata – Four Spotted Skimmer
The Alaskan State Insect

Dragonflies and their close relatives, Damselflies, come in a dazzling array of colors and patterns, ranging in size from less than  an inch long up to the South American Megaloprepus caerulatus with a wingspan of over 7 inches.  The largest dragonfly we know of is from the 300 million year old fossil Meganeura that had a wingspan of over 2 feet.

Dragonflies are powerful hunters, both in their nymph and adult stages.  Dragonfly nymphs are aquatic and prey on any animal or insect they can grab with their claws or their extendible jaws.  Insects, small fish, tadpoles, and small amphibians are all food for these voracious predators.  The nymphs are large, and, in turn, are prey for a wide range of other animals, insects, birds, and fish.  Elva Paulson has some wonderful watercolors of a dragonfly emerging from its nymph stage.  Humans are included as predators, many Asian cultures eating both dragonfly nymphs and adult dragonflies as delicacies.  One of the most tasty things I’ve eaten (from a long list of foods most people would consider to be unusual) was a plate of deep fried dragonfly larvae.  Absolutely delicious.  In Beijing I would sometimes find adult dragonflies candied in liquid sugar, their wings crispy with the hardened sugar.

Unknown green dragonfly – note the barbs on the forelegs for catching prey

The adult phase of a dragonfly’s life is short, in temperate climates only the length of the summer.  This is their mating stage and it takes them between 2 months and 6 years living under water to reach this stage.  Dragonflies are extremely active during this mating phase and must eat often.  They have enormous eyes giving nearly 360 vision, incredibly swift reactions, fast, powerful flight, and wicked barbs on their legs to assist capturing insects in flight.  The inset above shows these barbs.

Libellula exusta – White Corporal (I think)
eating its prey

The common names of dragonflies often reflect their speed or their abilities as hunters.  Meadow-hawk is one of my favorite names, and watching one dart away to catch an insect and return to its roost to devour it definitely brings hawks to mind.

Libellula quadrimaculata – Four Spotted Skimmer
note the different wing heights

Dragonflies are powerful fliers.  They have been clocked at over 35 miles an hour, fast enough to get a speeding ticket in a school zone, and, like hummingbirds, can fly forwards, backwards, sideways, up and down, and hover.  Their backs are sloped where their wings anchor, placing each pair at different heights, allowing for tremendous wing mobility.  Some species of dragonfly migrate, but the scale of some of those migrations has only recently been realized.  One dragonfly species in particular, the Globe Skimmer (Pantala flavescens) flies from India to Africa and back, island hopping cross the Indian Ocean, making open water crossings of nearly 1000km (620 miles) between island stops.  The only places they can breed are at the Indian and African ends of the migration, many of the islands they use as stopover points do not have sufficient freshwater for dragonflies to breed.  This is a stunning feat of flying for an insect and may be a behavior that evolved as a result of plate tectonics splitting India and Africa apart, eventually thrusting India into Asia.  If so, this migration could have begun 135 millions years ago.  Unfortunately, we have no reliable way of telling if this is the case.

Last year was a good year for dragonflies in Vermont, and this year looks like it is shaping up to be a good one as well.  The ecologist in me cannot help wondering why and one idea is that it may be linked to the calamitous drop in bat populations as a result of white-nose disease, a fungus that infects hibernating bats, weakening and eventually killing them.  It may be that adult dragonflies have more to eat with fewer bats and a greater percentage of them are surviving through the summer.  There is a historical precedent for this sort of boom in insect populations.  During the Great Leap Forward, Chairman Mao promoted a policy of killing off all things he thought were eating grain, birds amongst these.  With the crash in bird populations in China the insect population exploded.

Unidentified dragonfly – maybe a Darner of some sort

I am happy to see the dragonflies here.  Their presence means that the water is clean, we will have fewer mosquitoes, midges, and black-flies, and they are extraordinarily beautiful creatures.

Three-hundred twenty-five millions years old and going strong.  They have it figured out!

Blue-Eyed Grass, diminuitive irises

From California to New England, from Alaska to Texas there is a small, easily overlooked wildflower that is blooming now and will continue to do so for several more months, depending on where you are of course.  The flowers of this plant are small, only a little more than a centimeter across have six petals, a yellow center, and are often blue in color, hence one of the common generic names, Blue-Eyed Grass, although there are yellow and white variations.  To see them clearly you have to get close, crouching or laying on the ground.

Common Blue-Eyed Grass (Sisyrinchium montanum)

You can see from the photo that the leaves of this diminutive plant are broad and flat, much like the leaves of the grass it grows amongst.  In Vermont there are several variations of this plant, Sisyrinchium montanum being the most common, hence the name, Common Blue-Eyed Grass, which is, unfortunately, not tremendously imaginative.  When it is not flowering it’s easy to see why it might be mistaken for a grass, it has a similar leaf shape and is of a similar height to the grass it grows amongst.  The flowers clearly set it apart though.  Petals are little flags to attract insects, birds, and in some cases lizards or mammals to the flower for pollination for which they are rewarded with nectar.  Grasses have no such need, like willows, poplars, and pines they rely on wind to distribute their pollen and petals are a hindrance and a waste of energy for a plant that uses wind rather than animals for pollination.

Wind pollinated grass flowers with Blue-Eyed Grass flowers in the background

Sisyrinchium, the Blue Eyed-Grasses are tiny irises.  The Iridaceae family is widespread and often used as ornamental plants in gardens or in bouquets.  The larger irises have showy, ornate, soft flowers that fold and flow in complicated shapes, looking little like the small, robust Sisyrinchium flowers.  In the wild, the larger irises tend to grow in places that are either damp, shady, or both.  The Blue-Eyed Grasses live in harsher regions, open meadows, occasionally on rocky ledges, the edges of open areas, in short, places that can get hot and dry.  This may partially explain their small, robust stature.

Like other irises Sisyrinchium has inferior ovaries, this is not a commentary on the quality of the ovaries, it is a botanical term meaning that the ovaries are below the flower rather than the flower surrounding the ovaries.  These little plants produce globular three-part capsules about the size of a BB filled with numerous little seeds.

Blue-Eyed Grass with immature seed capsules

I grew up looking at these little flowers on the wildflower rich coastal prairie of Northern California, but just a few days ago I discovered something new (to me) about them.  They are active, they open their flowers for the day and close them for the night.  I tried my hand at a time-lapse of a flower opening.  It’s a bit rough, but you get the picture.

Blue-Eyed Grass flower opening animation

I love finding out things, being surprised by life, experiencing the unexpected, and encountering things I do not know.  I’m glad that these little irises reminded me that such a small, seemingly mundane thing can be interesting and exciting.

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: www.meteorimpactonearth.com

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 geology.com

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.

Bryophyta, Ancient and Tough

An ancient creature is waking up.  These creatures are small in stature but extremely tough.  They have been around longer than plants, although we often lump all green sessile things together.  Mosses are different though.

They have neither roots, nor vascular tissue, the plant equivalent of our circularity system.  They anchor to the substrate with little hold-fasts, somewhat like those giant algae, sea-weeds, and they drink though diffusion and osmosis.  They do well in places that are rich in airborne moisture.

Another things mosses lack is flowers and the associated seeds.  Like ferns, club-mosses, horsetails, and fungi mosses reproduce by spores.  By the millions.  They invest in quantity over quality and don’t pack any food or protection for their offspring before they cast them to the wind.  The spores will only germinate under perfect conditions.  Orchid growers are familiar with this problem, as orchids try the seed equivalent of this strategy.  Their dispersal strategy is like colonizing the galaxy by putting people in zip-lock bags and flinging them out of the solar system in the hopes that one of them eventually hit an earth-like planet.

This time of year the capsules that held the spores look like fossilized wind-socks.

Mosses are incredibly tough and individual stems from a colony can be very long lived.  A common way of judging the age of stair-step moss is the count the feather-like branches on a stem.  Five and seven year old moss stems are common and there are other mosses much longer lived than that.  An established moss colony may been in place for thousands of years.  Especially colonies in cold environments.

In the northern hemisphere we tend to think of plants and animals going dormant in response to cold.  If you can prevent the water in your tissues from freezing the danger for plants becomes one of dehydration.

Mosses, as I have said, are tough.  And Ancient.  They have some tricks they have learned over the hundreds of millions of years they have been around.  They learned these tricks before the ancestors of most of the things we see around us evolved.  Dinosaurs are latecomers to the party by the standards of the mosses.

Mosses dry up.  In a way the lessons learned as a spore transfer to the adults.  Most of their water evaporates, and as it does so the moss tissues curl in predictable ways.  The pores through which they breath close. Mosses can wait a long time like that.  Some mosses are so good at surviving this way that they grow in deserts.

Air in cold environments often contains less moisture than desert air.  Vermont has been even dryer than usual and many of the fir-cap mosses are still tightly furled, waiting for water.  Many look like the dry spires in the picture above.

Others have found enough water to wake up.

Like sponges, moss colonies trap water and fine debris.  The debris falls to the ground in the suddenly still water and becomes a nutrient supply for the mosses once they rehydrate.  Much like flowers they open as their tissues fill with water.

The growing tip opens as it hydrates revealing a tight furl of nascent microphylls (moss and clubmoss leaves) tinged a rosy hue.  Cold is well and good for living slowly, but growth requires warmth and the tips of the moss are shaped like little parabolic reflectors.  They trap both water and the sun’s light.  The reddish color may help them adsorb the long-wave understory light once the forest above leafs out.

From now through summer the new spore capsules will ripen, and come fall and winter they will scatter their spores across the landscape to drift with the wind, flow with the water, and run across the snow.

Unlike the poor fellows in zip-lock bags hurtling between the stars, the mosses have stacked the odds a little for their offspring.

Where water splashes moss may grow.  Where wind dies and lets drop what it carries moss may grow.  Where snow is late to melt moss may grow.

NOTE: The three close-in photos were taken though a 10x hand-lens held to the front camera of an iPhone4.

Ice to Water – Rock to Liquid

One of the most impressive, magical, and least appreciated spring changes is taking place right now in Vermont and through much of the northern portion of the globe.  In damp, shady, north facing areas ice is melting, becoming water.

This is a remarkable transition, a hexagonal mineral, ice, is, all by itself, changing its phase state, becoming an amorphous liquid.  In essence, boulders, cliff faces, and sand banks are melting and flowing away.  It is as though the rocky hills and mountains of the world slithered into the valleys and flowed to the sea every year.

The big solid blocks of ice form in the same manner as igneous rocks, water taking on the role of cooling magma.  A frozen waterfall is akin to a solidified flow of low gas content lava in Hawaii or Iceland.

Melting ice soaks into the ground carrying the sun’s heat with it, defrosting the frozen ground, waking up trees, plants, and animals, recharging groundwater resources, making streams flow, and redistributing nutrients.

The ice fall to the right was formed last winter from ground water seepage.  The base of the icefall spreads, molasses like, over a steep slope of boulders covered in decaying leaves, richly organic soil, and moss.  The melt water sinks directly into the ground, speeding the decomposition of leaves and woody debris, trickles down to the shallow bedrock, flows along this impermeable surface, and reemerges downslope in the company of ostrich ferns, blue cohosh, maiden hair ferns, and red cup fungus.

Right now, most of the plants are still waking up, small shoots and sprouts just beginning to emerge from the thawing ground.  Some plants have a jump on the process.  In relatively undisturbed areas of the New England forest near steep streams and seeps a forest dwelling sedge has been waiting all winter under the snow.

Carex plantagineaSedges are more often found in the open, in wet fields, swamps, marshes, and the like, but plantain leaved sedge (Carex plantaginea) is a true forest dweller.  It is an evergreen perennial with broad, thin leaves to best collect the dim sunlight that penetrates to the forest floor.  It lies flat under the snow, perhaps beginning to photosynthesize even before the snow fully melts, relying on the light that filters through the fluffy layer of sand-like ice that is snow.

Undisturbed stream banks, are festooned with this early wakening plant.  Sometimes it looks as though someone scattered dozens of limp green pompoms over the ground near the streams.

These small streams are particularly active this time of year.  The tumble down steep slopes, splashing from cobble to boulder, their flow more a series of miniature waterfalls than anything else.  The constant churning and splashing oxygenates the cool water, this oxygen allowing insects and amphibians to live in the steep streams and fish to live in the deeper, more slow moving rivers.

On a sunny day there is little more enjoyable than to sit in the forest listening to the sound of swift moving water and let your eyes and mind wander the landscape.

Water in Winter

Water in winter is a precious commodity.  At first thought, this doesn’t make a lot of sense, here in Vermont the ground is covered in snow, which is, after all, merely water in a specific phase state.  Despite this being a meager winter in terms of snowfall, there is between 1 and 8 inches of snow, depending on where you are, on the ground near my house in northeastern Vermont.

The problem is three fold, 1) that phase state issue.  Snowflakes are delicate ice crystals, and ice has a Mohs hardness of around 1.2-2 at normally cold temperatures.  This is harder than chalk and talc.  Ice acts as a soft rock.  2) Humidity, the ability of the atmosphere to hold water is dependent on temperature.  The same relative humidity at different temperatures means very much less total available water at a colder temperature.  At cold temperatures things dry out quickly, which is part of the reason deciduous trees drop their leaves, and why other plants cover their leaves in waxy coatings or thick layers of hair.  3) the ground is frozen, locking up surface water and making it unavailable to plants and animals.

These factors combine to make winter a stressful time for plants, but for animals the cold makes it even more difficult.  Animals have several options for dealing with cold; they can hibernate, dropping their temperatures and metabolic needs to a bare minimum and wait out the difficult times; they can insulate themselves with layers of fur or fat to protect from the cold; or they can ramp their metabolism up to generate more heat.  The problem is that generating heat via metabolic activity takes water… where do you get it in the winter?

Today was a warm winter day in my portion of Vermont, somewhere in the high 20s, and the snow had melted away some since the last snowfall.  About 50 feet behind my house I came across the tracks from a fisher that had been hunting several days earlier.

Being inquisitive, I followed the tracks.

In typical mustelid fashion they wandered semi-randomly across the landscape, but, as I followed them, more and more tracks came together, making a veritable highway of frozen tracks in the snow.

More and more tracks came together, both of fisher and of deer, coyote, and bobcat.  Clearly I was onto something, but what?

At first, when it was just fisher tracks, I had been hoping to find a den.  If I could find a den, I might be able to justify finally buying a game camera, something I have wanted for a long time.  I found a dead sugar maple that might be a den, but as I continued exploring, that was not where the greatest number of tracks was.  Maybe I would find a kill site.  A scattering of porcupine quills or several puffs of squirrel fur.

Nothing of the sort greeted me, but what I did find was a small frozen pond fed by ground water and surrounded by tracks and scat from all sorts of animals.

Ground water, that is the key.  The earth has tremendous thermal mass.  Thermal mass is a sort of battery or reservoir of heat (there really is no such thing as cold, it’s all varying degrees of heat, with no heat being 0 kelvin, or absolute zero).  In my region of the US the ground stays at a relatively constant 50 degrees F.  In the hot and humid summers that means all the rocks sweat, condensation forming on their (relatively) cold surfaces, and well water is refreshingly cool to drink and chilly to bathe in.  In the winter this means that seeps and springs stay running and liquid all winter, and well water feels deceptively warm (though still chilly to bathe in).

The fisher I had been following was heading to a source of water, water that drew numerous other animals, including a bobcat that left scat at the base of a hemlock tree and probably hunted the other animals that came for water.

The fisher I had been following, and, perhaps several others, has spent quite a lot of time at this pond.  The tracks were melted into the ice all around where the liquid water came into the pond.

Even in a place as water rich as Vermont, water can still be a precious commodity.