50 WILLIS T. LEE 
sandstone formation approximately 300 feet thick and composed 
principally of variegated clay-shales and friable sandstones. 
Limestones of varying degrees of impurity occur with more or 
less frequency according to location. At the point represented 
in the detailed section (Sec. 4) the limestone layers are nearly 
all at the top. A few miles from this point a well exposed sec- 
tion exhibited no limestone near the top, but a stratum of bluish- 
green limestone several feet thick occurs near the middle. In 
no two sections studied do the limestones occur at the same 
horizon. The sandstones of this formation in the Canadian 
Canyon compose a notable part of the thickness (about one third 
to one half). The various layers differ in character from firm, 
well-cemented masses to beds of loose-textured sandstones which 
disintegrate with the greatest ease. They vary from masses of 
nearly pure silica through various admixtures of sand and clay 
to nearly pure clay. Near the middle of the formation occurs a 
slightly cross-bedded layer of sandstone which seems to be 
more persistent than the others, although this cannot be confi- 
dently stated. The shales are soft and weather readily except 
where they are intermingled with sand or lime in sufficient 
quantities to render them resistant. They are colored in various 
shades of red, brown, and green. In short, they differ in no 
obvious manner from the shales which I have already described 
from the canyons of the Rio Cimarron and the Purgatory. 
The transition from the massive sandstone (Dakota) at the 
top to the shale formation is abrupt, but no definite evidence of 
unconformity was seen. The base of the shales is not marked 
here by gypsum as in the canyons of the Rio Cimarron and the 
Purgatory. In its place occurs the coarse, massive pink sand- 
stone shown in the section and in the photograph (Fig. 7). No 
evidence of unconformity was found at the base of the shales, 
and the line of delimitation is drawn at the top of the heavy 
sandstone because of the marked change in character and com- 
position at this horizon. No fossils were obtained from the 
shale formation of the Canadian, and its correlation must rest, 
for the present, entirely upon stratigraphic and lithologic 
