MORRISON SHALES OF COLORADO AND NEW MEXICO 47 
stone conformably. It is noted, furthermore, that the shales, as 
a formation, do not vary in any marked degree either in character 
or thickness. Whatever may have been the physical conditions 
prior to the deposition of the shales, it is evident that the shales 
were deposited over a well-graded surface. It follows also that 
there was a somewhat notable time-interval between the Red 
Beds and the shales. A part at least of this time-interval is 
represented by the unconformity between the Red Beds and the 
Exeter sandstone. It is uncertain whether there is a time break 
between the Exeter sandstone and the overlying shales. How- 
ever this may be, the seeming conformity which exists in many 
places between the Red Beds and the shales is deceptive. The 
contact really represents the whole time indicated by the uncon- 
formity between the Red Beds and the Exeter sandstone and 
the time required to form the Exeter sandstone, besides the pos- 
sible period between the deposition of the Exeter and that of 
the shales. 
The region south of the Rio Cimarron.—In the course of the 
journey from the Rio Cimarron to Clayton and thence westward 
to Springer, no stream was found which had cut entirely through 
the Dakota sandstone until the Canadian River was reached. 
There is, therefore, a space of about sixty miles —the space by 
which the nearest points of the Rio Cimarron and Canadian can- 
yons are separated —in which the shale formation was not seen. 
It has been penetrated, however, by wells. One well several 
miles northeast of the Don Carlos hills—-nearly due south of 
Folsom—was drilling at the time I visited the region. The 
drill had penetrated the Dakota sandstone and was then cutting 
through a series of soft shales. The engineer in charge of the 
work described the formation as ‘‘a soft clay of different colors 
containing a few sand layers and thin seams of a smooth whetrock 
without any grit.” The ‘‘whetrock without any grit”? was probably 
one of the argillaceous limestones of the shale formation. 
Canadian Canyon.—The canyon of the Canadian begins where 
the river penetrates the Dakota sandstone a few miles south of 
Springer, N. M. For about fifty miles it is a narrow gorge sev- 
