i?. S. Tarr — The Permian of Texas. 11 



The Permian occupies the basin between these two Carbon- 

 iferous areas, which are several hundred tniles apart, the basin 

 being a syncline formed by the west dipping Carboniferous of 

 the east and the east dipping rocks of the Guadalupe and 

 other mountains of western Texas. The Permian strata are 

 themselves folded into a very gentle, almost imperceptible, 

 syncline, being almost, if not quite, conformable to the gently 

 dipping Carboniferous beds on which they lie. 



The line separating the Carboniferous from the Permian on 

 the east is very indistinct, being traceable only with difficulty. 

 Mr. Cummins reports an overlap or slight unconformity at this 

 contact, though its exact value is not determined as yet. 

 Where seen by the writer there seemed to be an almost imper- 

 ceptible gradation from upper Coleman to Permian. Small 

 overlaps abound in the Coleman series and it is possible that 

 the overlap reported by Mr. Cummins has but slightly more 

 value, though this is suggested only tentatively. 



The facts stated above show in later Carboniferous times a 

 shallow water condition at points several hundred miles apart. 

 In the east, in particular, the conditions are those of a shallow 

 sea skirt by newly made land of unconsolidated strata. It 

 cannot be affirmed from the evidence at hand that this was a 

 Mediterranean sea, but indications point to that conclusion. 

 The great extent of similar beds, in both central and west 

 Texas, are rather against the supposition of estuarine condi- 

 tions. I conceive for this period a condition not unlike that 

 of the present Gulf of Mexico. The Paleozoic and pre-Paleo- 

 zoic core of central Texas was skirt with the recently added 

 coastal strip of Carboniferous strata, and the connection with 

 the Arkansas and Indian Territory mountains was complete. 

 What formed the enclosing barrier on the south and west we 

 have no means of knowing in the present meagre knowledge 

 of the geology of these regions. 



This is not pure unconfirmed conception, for the subsequent 

 events of Permian time point quite conclusively to this explan- 

 ation. That the Permian in its most typical development was 

 a completely enclosed sea is proved beyond a doubt by the 

 nature of its beds. In no other way can the numerous layers 

 of gypsum and salt be accounted for. The redness of the clay 

 and sandstone beds is then easily explained, though for this 

 other explanations are possible. The peculiar sickly gray color 

 of the limestone is that of an inland sea deposit, the remarka- 

 ble absence of fossils in most of the beds points to the conclu- 

 sion already drawn, and the abundance of vertebrate fossils of 

 land and inland sea types is thus readily accounted for. The 

 presence of extensive conglomerates with very large pebbles 



