PERMIAN. 397 



which were abundant in the Carboniferous are not found in the Triassic. I 

 claim therefore that any strata that contain both of these characteristic or 

 peculiar forms ought to be put in the Permian. 



CONFORMABILITY. 



The conformity of the dip of the Permian Beds with that of the Coal Meas- 

 ures in Texas has everywhere been observed, and this is in striking contrast 

 to the unconformity between the Permian and Triassic. At places where the 

 lower beds of the Permian lie in immediate contact with the Coal Measures 

 it is almost impossible to determine the line of contact. This boundary is 

 rather arbitrary than otherwise, since both are either sandstones or clay beds, 

 and it is only after passing away from this line that one is certain that he has 

 left the one and is upon the other. I doubt not that if the Permian had first 

 been studied at this locality it would have been put with the Coal Measures; 

 but being first studied in Saxony, where an unconformity exists and where 

 it is impossible to trace a gradual passage from one to the other, a different 

 series was established. Again, at the contact between the Coal Measures 

 limestone and the middle beds of the Permian there is such a conformity be- 

 tween the two that no one would suspect but that they were a continued sedi- 

 mentation; and the break is known only by the character of the material 

 composing the strata, and the faunal life. A gradual submergence of the 

 strata is the only movement that seems to have taken place during the time 

 of the Coal Measures and Permian in Texas. 



When I say there is no unconformability between the Permian and Coal 

 Measures at this contact, I mean to say that there is no greater unconform- 

 ability between them than there is between the different divisions of the same 

 series. We find in Texas, in both the Permian and Coal Measures, that the 

 earlier divisions dip at a slightly greater angle than those of a later date, so 

 that if the top of the Coal Measures should be found resting upon the lower 

 part of the series there would be a slight unconformability; and so of the con- 

 tact betv/een the Permian and Carboniferous. South of the Brazos River, at 

 the contact between the Clear Fork division of the Permian and the Albany 

 Beds of the Coal Measures, which are the highest division of the Coal 

 Measures in Texas, a period of time intervened which is represented in Texas 

 by the Wichita Beds of the Permian. 



Again, at the line of the contact between the Wichita division of the Per- 

 mian and the Cisco division of the Coal Measures, on the north side of the 

 Brazos River, there is a period of time intervening which is represented in 

 Texas by the Albany Beds, and therefore at this contact there is a slight non- 

 conformity, which can only be discovered by actual measurements. By cas- 

 ual observation of the strata one could be very easily led to conclude that 

 there was continued sedimentation. 



