10 NEW REPTILES AND STEGOCEPHALIANS FROM 



cap-rock. At Spur, a few miles south of Dickens, it has the same position, forming 

 the hill, in the north part of the town, upon which the water-tower is located, and 

 is easily traceable in the small elevations which can be seen in all directions for 

 miles from that point. West of Spur it is the surface rock, appearing at intervals 

 through the surficial clays and sands to within a few miles of the Blanco or Catfish 

 River, where the lower formations are again visible in the breaks. On the east 

 side of the river the Triassic is much obscured by the accumulation of wind-blown 

 sand, but on the western side the bluffs are prominent and stand out as conspicu- 

 ous features similar to the bluffs at Dickens. Such a prominence is Cedar Moun- 

 tain, between the forks of Sand Creek. From the summit of these bluffs the hand- 

 level shows that the tops of the hUls are approximately on the same level. The 

 beds below the conglomerate cap in this region are decidedly different from those 

 shown in the Croton Breaks east of Dickens; there is much less of the deep-red 

 clay and relatively httle gypsum. The beds are composed of light-red or yellowish 

 clay in most of the exposures. Though there is considerable continuity in the 

 beds, there is a decided irregularity of deposition exposed in the breaks of Holmes, 

 Sand, and Davidson Creeks near Cedar Mountain; here there are frequently 

 lenses and intercalated beds of hght cream-colored clay, light-bluish clay, and 

 light-red clay, with abundant irregular concretions and nodules. By far the 

 greater number of the beds, and uniformly those which are at all regular in their 

 deposition, are totally barren of fossils. It is only in the irregular beds which 

 were evidently deposited in stream-channels and local pools that any remains are 

 found. It is evident that this area, which is so different from that of the Croton 

 Breaks, is the site of some great stream-channel and flood-plain. 



Unfortunately, only a small area is exposed in the breaks, and a careful search 

 of the whole eastern side of the Plains has revealed no similar locality. Water- 

 worn fragments of bone frequently appear in the conglomerate; some were collected 

 as far south as the vicinity of Slaughter's Ranch, 18 miles southwest of Post City 

 in Garza County, and traces of bone were found east of Big Springs, but it is evi- 

 dent that the areas where vertebrate fossils may be collected in any quantity and 

 in a usable state of preservation are very limited on the eastern side of the Plains. 



The exposures of the Triassic in the breaks of the Canadian River, in the 

 northern part of the Plains, show a more or less uniform series of red beds, clays, 

 and sandy shales, with occasional bands and veins of gypsum beneath the conglom- 

 erate. These beds can not be exactly located in Drake's series, but appear to be 

 the ones located in his upper division, though Permo-Carboniferous vertebrates 

 have been reported from the vicinity of Plemons in Hutchins County, and the 

 Texas Geological Survey has mapped Permo-Carboniferous in the western part of 

 Oldham County. 



On the western side of the Staked Plains a splendid view of the exposures of 

 the Triassic can be had from the edge of the cap just west of Adrian in Oldham 

 County. From this point it is possible to see a large area of the breaks in the 

 upper part of the Canadian Valley and much of the area to the south, almost to 

 Glen Rio on the Texas-New Mexico line. The land is roughly rolling and much 



