Fractured siliceous sedimentary rock, Marathon basin, West Texas


I collected this in 1964 field trip to west Texas from Austin, where I was a Masters student at UT-Austin. It was on this trip that I experienced the enormous size of Texas; seemed to take forever to get there.  Moreover, I had never seen more geologists in my life; more than 200 attended, many from industry.  Schlumberger, Inc., provided quantities of beer for three straight days from morning to night, and I recall how surprising it seemed to me that  some geologists were frustrated with Schlumberger when the company ran out of beer on the last day.  Besides these recollections, I like this rock because of the pervasive fracturing, the possibility of shear jointing, and the curviplanar and discontinuous nature of some of the fractures.  Even at the time I collected it I felt that it contained a lot of history.

Age & Formation
Caballos Formation of Devonian age, ~385 Ma.