Sunday, January 30, 2011

Evolution

I'm fascinated by the process of evolution.

The Texas Hill Country is ribboned with rivers.  Most spring from permeable limestone formations imprisoned by dense rock. The rivers make this land habitable.  And desirable.

Denny and I drink water from the Edwards aquifer, a formation of limestone created and eroded as shallow seas rose and fell, until water could pass through the limestone, trickling, flowing through cracks, fissures, crevices, caverns.  

The Edwards was eventually surrounded in dense layers of rock, until it became a captive limestone vessel.  
Map from the Edwards Aquifer Website. 

One imprisoning layer, the Del Rio Clay, "consists primarily of windblown ash that originated with volcanism on the Pacific coast of Mexico." (1)

I don't think of Pacific coast volcanoes when I go down to the Guadalupe River and dabble my toes in the swift cold water.  But if, somewhere in the stretch  between 248 to 65 million years ago, ancient volcanic ash had not erupted and been carried here, the Texas Hill Country would support little human life.

Today the Hill Country is a land of stark beauty, a good place for contemplation and exploration.  
We came from yesterday, but today is ours.

(1) from Hydrogeology of the Edwards Aquifer

Copyright 2009-2011 Kathleen Scott, for Hill Country Mysteries. Unauthorized reproduction is prohibited.
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