1903.] Gidley, Fresh-water Tertiary of Northwestern Texas. 635 



Creek are evidently of the same age. They closely resemble 

 each other in a general way, and the formations are traceable 

 from one locality to another around the irregular escarpment 

 of the Plains. Numerous wells dotting the Staked Plains 

 show everywhere the existence of these beds. They are of 

 nearly uniform thickness, and form practically the whole area 

 of the Staked Plains. 



Summary. 



Following is a summary of the conclusions reached by the 

 writer from this study of the formations of northwestern 

 Texas : 



(i) There has been no great disturbance or change of level 

 in the region of the Staked Plains since the close of the 

 Triassic, hence the strata of the Triassic which underlie this 

 whole region are for the most part nearly horizontal, and the 

 country at the beginning of the Miocene was comparatively 

 level. 



(2) The Panhandle (Lower or Middle Miocene) beds were 

 comparatively evenly distributed over the vast area now 

 occupied by the Staked Plains and in addition extended 

 westward to the Rocky Mountains in New Mexico, and spread 

 out to the eastward over a much greater territory than they 

 now occupy. These deposits seem to be, at least partially, 

 lacustrine in origin. 



(3) All the formations of the Staked Plains that are of more 

 recent date than the Lower or Middle Miocene are represented 

 by comparatively small areas, and are fiuviatile, or aeolian and 

 fluviatile, in origin. These later depositions are represented 

 by the Clarendon beds in the vicinity of Clarendon, the 

 Blanco Beds at Mount Blanco, and the Rock Creek beds at 

 Tule Canon and Rock Creek. 



