Stop 5: Geology Basics

 

Geographical formation in Stebbins Gulch

 
 
This is a beautiful example of a geologic “contact,” i.e., a plane in this instance, a horizontal one that separates two distinct rock types.  Just above water level we see the top three feet of a blue-gray marine shale known as the Chagrin Shale.  Above the contact, clearly seen as the edge of a horizontal surface, is the younger, dark-colored, fissile Cleveland Shale, an oil shale. This rock unit is world famous for the fossilized remains of extinct armored fish and primitive sharks that have been found in the Cleveland area. Similar flat-lying, essentially unaltered sedimentary formations cover all of Ohio.    

 

 
   
Stebbins stratigraphy
 
       
           
 
Siltstone and shale
       
       
           
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