Monday, March 11, 2013

What is an Esker?

 If you are like me, you haven't a clue about eskers.  Or rather, I did not have a clue until I recently visited a very special State Nature Preserve in Champaign County.  This area is within striking distance of West Liberty and Urbana, Ohio.

 Our story starts at the sign.  This area is significant because it is a glacial relic. Since the primary reason to visit this location was to learn how land masses were moved and formed by glaciers and melt water, it is best to visit in the winter, when one can get a good look at the topography.

 A good plan, however, a Weedpicker like me can still get distracted by a simple row of trees. Can you name this species?

Now can you name it?  Check out the "warty" bark.
Those "warts" are layers and layers of tree bark.  This is the accumulation of 
many single year's layers of growth, all stacked up like a deck of cards.

The warty bark is a significant feature for the Common Hackberry tree, Celtis occidentalis.  It is a disease resistant native that provides habitat for both birds and butterflies.  Everyone needs a Common Hackberry in their lawn.
Now the trail has lead to some interesting land formations.  Note the rise to the right?  That was formed by a stream buried within a glacier.

Formation of an esker.

This formation is called an esker. It was created when  particles of sand and rock sunk to the bottom of  melt water. In time it built up and was formed by the ice walls which remained. The Department of Mineral Resources in North Dakota does a decent job of further explaining these formations. Just go right here. 

Those large oaks are well over a hundred years old. They are a magnificent sight, riding atop of the esker. Note how the top surface of the formation is relatively flat.

Being no whiz at geology,  I am just beginning to appreciate these formations created by ice shifting all across Ohio.  Glaciers, grinding across our land, moved rock and sand in such massive scale they determine our land uses today.  Flat glaciated land gets farmed.  Rocky gorges (like Mohican) are not suitable for the plow.  Eskers, were made for pure wonder.  They are a modern day connection to the ice age.

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