56 VVILEILIES Hl, ShJos a; 
tion of the upper 50 to 100 feet, seem to be identical with the 
lower series of the Rio Cimarron and the Purgatory. The Red 
Beds of the Canadian are referred to the Permian by Mr. R. T. 
Hill,; While the age of the Red Beds is not of first importance 
in my present purpose, it may be noted incidentally that no dis- 
tinction was found between the Permian of Mr. Hill at the south, 
and the so-called Trias at the north and west. 
The Exeter sandstone is separated from the Permian by a 
time break in the Rio Cimarron. Its character and general field 
relations are similar to the upper massive series of the Canadian 
Red Beds. While there was no evidence of unconformity noted 
in the Canadian, it is possible that the upper series is of the same 
age as the Exeter sandstone. Mr. Hill, in his description of the 
Texas Region, speaks of a thin formation overlying the Permian 
which is referred to the Trias with some doubt. Hesays: ‘‘The 
existence of the early Mesozoic (Triassic) is doubtful although 
possible. Rocks referred to this period overlie the Permian 
along the western part of the Central Province, and appear in 
small areas around the border of the plateau of the plains.’’? 
The latter region embraces the southern portion of the area 
under consideration in this paper. It is possible, then, that the 
upper part of the Red Beds of the Canadian and perhaps the 
Exeter sandstone of the Rio Cimarron may be of Triassic age. 
If this be true the shale formation rests upon both Permian 
and Triassic rocks. 
On the other hand, the Exeter sandstone may belong to a 
later age than the Trias. If the upper series of the Canadian 
(the possible Trias) represent not the Exeter sandstone, but that 
portion of the Red Beds removed by erosion where the Exeter 
sandstone now occurs in the Rio Cimarron, then the Exeter may 
be a younger formation—possibly the Trinity sandstone. In 
Mr. Hill’s folio of the Texas Region he gives a ‘section show- 
b 
ing the geology of the Texas region.”’ This region embraces 
1“ Physical Geography of Texas Region,” U. S. Geol. Surv. Topographic Atlas, 
Dp: 2: 
2?R. T. HILL, Physical Geography of the Texas Region, p. 3. 
