A Study in Ice

A Study in Ice

February 2, 2014

It was an icy day, but with no snow.  The temperatures had stayed below freezing for a good part of the winter, sometimes well below.

For several previous years, our area had been experiencing abnormally mild winters, with higher than normal temperatures and only occasional snow or ice.  When we did get a good pile of snow, it would melt by the afternoon or the next day.  Many local people got used to that as a “new normal”.  They have been doing quite a lot of grumbling this winter.

But not I.  I am happy to have a normal winter of deep cold, ice, and (often) an insulating layer of snow.  

This is what Nature has adapted to here, a place where blocks of ice were cut and harvested from the rivers years ago.  We need sustained cold to control the populations of insects and some other types of animals.  We need the snow to help protect burrowing animals, as well as tubers and roots under the ground.  We will need a good melting of snow and ice in the spring to refresh the water table, streams and ponds.

And so, I have delighted in finding out how Cottonwood Pond and its environs look during a real winter, and how it is affected.  

On the way down, I saw the lower end of the “resting log” sparkling in the winter sun.

Each cream- and tan-striped fungus had a sheen of thin ice on its fan-shaped surface.

Some even had a network of small, glass-like, sparkling crystal fingers.

The creek was not completely frozen.

 

    There were layers of ice, with water flowing beneath or between them.

 

 The action of water flow and some melting caused various designs to form.

  

Crystals formed around the inside edges of holes.

 

The new pond-like area of to the side of the creek was frozen.  Leaf piles, pushed up by rushing water during a previous flood time, rimmed the little pond.

A channel-like depression was still frozen in place within the seep, between Cottonwood Pond and the creek.

Cottonwood Pond was covered by what looked like a thick layer of ice.

Light-footed Silas took a walk all the way across.

Bubbles of many different sizes were frozen into the surface.  Why had these formed?  There were no frozen ripples this time to indicate wind stirring the water surface and adding oxygen.  Had there been much oxygen trapped below, then quickly released during a brief warming, followed by a quick, hard freeze?

Toward the north end of the pond, the bubbles tended to be smaller and to congregate in large groups.  

In places, they looked like constellations.

Some larger bubbles had collected around leaves.

Were these frozen, or still active?

They appeared to be full of very tiny bubbles, like worlds within worlds.  Or were the very tiny ones just  beneath the large ones?

Near the middle of the pond, small bubbles had formed a large ring, with a small ring of seemingly foamy, swirled bubbles in the center. 

How did this form?  Had a store of oxygen bubbled up from the mud below and then rippled out at the pond's surface?  Or could it have been released from an animal burrowed in the mud?

An area of thin ice had formed close to the root ball, sprinkled with fine dirt particles that had fallen from the ball.  Ripples had formed in the ice where rootlets dipped into the pond. 

Was there movement of the rootlets due to wind when the water was freezing?

Looking up, I saw a clear burrow high in the root ball.  Someday I will wait here and see if the animal appears.

I went to the south end of the pond.

The large crawdad chimney was frozen so hard it looked and felt like it had been in a kiln.

A paw print, showing serious claws, was frozen into the mud.

 From right to left, it was still evident where the water had rushed to the south end of the pond during the flood (the “rush area”) and pooled under the log at the edge ...

...went under the log …

… and then entered the pond.

Flow lines, resembling lines of varying elevation on a topographic map, showed how water entered the pond's south corner.  

This time, though, the flow was obstructed by a strange, clear rod shape in the ice...

Did this ice form around a stick?  I wondered if incoming water had flowed over the stick (if there was a stick there) and froze in layers as water continuously moved over it.

When we have our next thaw, I need to look at this spot again.

Did this ice form around a stick?  I wondered if incoming water had flowed over the stick (if there was a stick there) and froze in layers as water continuously moved over it.

When we have our next thaw, I need to look at this spot again.

I moved back around to the other side, to see “little pond”.

 

“Little pond” looked to be in similar condition to the larger pond, though the ice layer may have been thinner.

It also had “constellations” of many bubbles.

There was the old Stinging Nettle plant that had dipped down from the root ball top to the water..  Some very interesting ice designs had formed around it.

With the frosty conditions of the day, the tiny hairs along the nettle's stem and leaf petioles were very visible.  They would no longer sting, though, as the plant was completely dry.

“Little pond”, as seen from the southeast.

“Little pond” on the left and Cottonwood Pond to the right, to either side of the fallen tree's giant root mass.  During the flood, water had rushed over the leaves between the two ponds.

I stepped back over to the north edge of Cottonwood Pond.

Silas had walked over the pond earlier.  How thick was this ice?

I put my booted foot over the edge, set it down, and began to add pressure.

A sudden snapping, crackling sound told me to go no further.

I had broken the nice smooth surface of the pond with its constellation of bubbles.  But, I had only cracked it lightly, and the cracks spread out into a beautiful pattern …

… like a spider's web.

I was reminded of the webs I had found last summer and fall, stretched between plants near the pond, between rootlets on the root ball, and stretched over the ground.

After I cracked the ice, I noticed movement.

Bubbles in the middle of the pond, further from the “web”, began moving in a mass exodus toward the edge of the pond, coalescing into larger bubbles at the edge.

So, the bubbles were “alive”, after all.  They were not frozen.  They were floating just below the surface of ice.  That layer was thinner than I had originally thought.  

Appearances can be deceiving.

I will do more thinking about the bubbles, and why they formed as they did. 

My study of ice had shown me patterns reminiscent of other things in the world:  spider webs, topographic maps, rods, crystals, constellations, and worlds within worlds.

At the end of my visit, a sheen of sunlight lay on the icy top of Cottonwood Pond in varying degrees of brightness.

I expect that the conditions and variations of the ice will continue to fluctuate with more changes this winter, and I will be fascinated to see them.