52 VULETE ST TELAT 
furthermore probable that this shale formation of the Canadian 
is identical with that of the Rio Cimarron and the Purgatory. 
Apishapa Canyon.— East of Walsenburg, Colorado, the Api- 
shapa River cuts through the Dakota sandstone, making a sharp, 
narrow canyon several miles long and something more than 300 
feet deep at the deepest place.* The greater part of the thick- 
ness exposed is sandstone. This occurs in two series separated 
by about 30 feet of dark colored clay-shale. The upper series 
forms the protecting rim of the canyon. It is about 100 feet 
thick, hard and quartzitic, and contains an occasional leaf 
impression. It weathers to a rusty brown color which seems to 
be characteristic of the upper part of the Dakota in this region. 
The lower series is massive, white, and less strongly quartzitic. 
In places the uneven induration permits cavernous weathering. 
The dark clay-shale between the two series is probably the 
layer of fire clay which usually occurs about the middle of the 
Dakota. Near Thatcher, Colorado, a few miles east of the 
Apishapa Canyon, fire clay is mined to some extent at a horizon 
which is evidently the same as that occupied by the dark shales 
of the Apishapa. The fire clay of Thatcher and the dark shales 
of the Apishapa are similar in color, character, and position, and 
are probably parts of one and the same deposit. Below the 
lower sandstone about 50 feet of somewhat highly colored shale 
occurs. In composition and character this shale is similar to the 
shales found in the Red Rocks Canyon, several miles to the east, 
underlying the Dakota sandstone, and are probably identical 
with them.? On the other hand a similar shale formation, and 
similarly placed, occurs in the canyon of the Huerfano River a 
few miles west of the Apishapa. The shales of the Huerfano 
are described by Mr. R. C. Hills in the Walsenburg Folio of the 
U.S. Geological Survey, and referred to the Morrison. There 
is little doubt, therefore, that the shales exposed in the bottom 
of the Apishapa Canyon belong to the Morrison. 
Extension along the mountains—Along the mountain front 
TSee U.S. Geol. Surv., Apishapa Sheet. 
? See Sec. 2, p. 347, JouR. GEOL., Vol. IX, No. 4, May-June, Igo1. 
