GEOLOGIZING IN TEXAS AND TENNESSEE 



By G. ARTHUR COOPER 



Assistant Curator, Division of Stratigraphic Paleontology 



U. S. National Museum 



It has been the writer's practice for some years to visit sections 

 of the United States from which few fossils are represented in the 

 National Museum collections. Accordingly, a visit to north-central 

 Texas and the Glass Mountains of west Texas was planned. Penn- 

 sylvanian fossils abound in the former locality, and the latter is noted 

 for its Permian fossils. In addition to these two areas the itinerary 

 also included west Tennessee, where Silurian fossils may be found. 

 The fact that important localities on the Tennessee River will soon 

 be lost under the ponded waters of the Gilbertsville, Ky., dam made it 

 desirable to obtain collections before these localities are lost. A brief 

 study of the Stones River limestone of central Tennessee was also 

 on the schedule. 



In early August the writer left Washington for Fort Worth, Tex., 

 where he joined Airs. J. H. Renfro and her daughter, enthusiastic 

 collectors and students of Pennsylvania!! fossils. With the Renfros 

 as guides to the better localities, the writer collected more than 10,000 

 specimens of beautifully preserved Pennsylvania!! fossils. Most of 

 the collecting was confined to Jack, Young, and Palo Pinto Counties, 

 where the Pennsylvania!! rocks consist of thin limestones interbedded 

 in thick sequences of shale and fine-grained sandstone. The rocks 

 lie nearly flat and are well exposed over most of the area. The shales 

 often disintegrate into clay, leaving beautifully preserved fossils lying 

 about on the slopes. Each rain helps to replenish the supply by wash- 

 ing away more clay. 



From Fort Worth the writer went west to Marathon, Tex., lo- 

 cated 60 miles south-southwest of Fort Stockton. Just north of 

 Marathon, in the Glass Mountains, is exposed one of the finest 

 sections of Permian limestone in the world, aggregating 6,000 to 7,000 

 feet in thickness and abounding in fossils, particularly in the lower 

 half. Most of these Permian fossils are silicified and can be removed 

 from the rock by dissolving away the limestone with acid. Shells of 

 unbelievable beauty and delicacy can be obtained by this method. 

 Besides the Permian specimens, good Pennsylvania!! fossils were 

 collected along the base of the hills about 23 miles northeast of 



