SUB-CARBONIFEROUS. 365 



from the Silurian headlands, and this corresponds fully with my observations. 

 The point I desire to make is that the strike of this series of strata is not 

 southwest but more nearly east and west, corresponding to the old shore line, 

 and that the beds of limestone and shales which extend from the eastern 

 edge of San Saba County to the town of Brady are no more than ten miles 

 wide, and instead of being a series of beds of limestones and shales there is 

 but one bed of shale; and one can start from Bend, in the southeast corner of 

 San Saba County, and travel on the same black shales to the town of Brady. 



From the base of the sandstones to the Texas marbles, which is below the 

 blue limestone in question, at no place has the strata a thickness of five hun- 

 dred feet, and instead of the limestones "striking up against the sandstone 

 and there ending," they simply pass beneath the sandstone. 



An examination of the completed sections of the Carboniferous of Texas 

 shows that this unconformability is no greater than exists in other portions of 

 the system. 



That there exists slight unconformity between the upper and lower mem- 

 bers of the same period is not to be wondered at when we take into consid- 

 eration the fact that there was a general subsidence of the whole strata during 

 the entire time, and which was at times more rapid than at others. There 

 would be times when the general submergence would stand still for awhile 

 until the limestone seas would fill up by the silt brought down from the lands 

 surrounding. The seas would become more shallow until the waters would 

 no more deposit limestone material, but the heavier clays, and they in turn 

 would be followed by sandstones deposited along the sea coasts. There were 

 doubtless also oscillations in the strata during these times — emergence as well 

 as submergence. Where there is a continuity of sedimentation there has 

 been no unconformability observed, and while it is a fact that the higher we 

 get in the geological series in Northwest Texas the less is the dip of the strata, 

 it is also a fact that at the place of contact between the different divisions 

 there is no unconformity observable. , s 



That there is a lapse of time between the deposition of the limestone and 

 shales found in the San Saba County and the overlying sandstone is a fact 

 that is easily understood by any one who has examined the Coal Measures in 

 Texas. Below the same sandstones where they occur in the northern part of 

 the Carboniferous formation, along the Brazos River, are several beds of lime- 

 stone that are undoubtedly Coal Measures, but which are different from the 

 limestones characterized by Mr. Tarr as Sub-Carboniferous, and which are so 

 connected by sedimentation that there is certainly no break in the forma- 

 tion in that region ; and besides, the limestones contain the well known char- 

 acteristic fossils of the true Carboniferous series, as may be seen by the list 

 of fossils given of that locality in another place. 



