038 KANSAS CITY REVIEW OF SCIENCE. 
else the great clay deposit overlying the coal, and east of the coal veins, either of 
these clay deposits being sufficient to arrest the outward flow of the drainage of 
our mountain range, thus acting as an impervious wall or dam, and forcing into’ 
the low-lying porous strata, under the clay, a vast volume of water, which is totally 
lost for any available purpose. It is evident, however, that in Jefferson and Boul- 
der counties, where the coal formation is extensively developed, that the amount 
of water absorbed and which passes under the great clay deposit that overlies the 
cual, is of very small volume compared to that which is stopped by the fire clay 
beds in the coal deposits against whose face the whole mountain drainage is finally 
accumulated, and which it follows to an almost unknown depth. 
We have been, perhaps, too particular in our local remarks touching the 
sequence of our geological deposits, and their situation in respect to the configura- 
tion and drainage of our mountain range, and its outliers to the East, formed of 
sedimentary rocks, but we consider these details as absolute, not only in general 
accuracy, but as necessary to develop the theory we have formed, based on their 
sequence and position. 
In accordance, then, with the preceding description of the geological and 
lithological formation of the strata adjacent to the Rocky Mountains, between the 
thirty-eighth and forty-first degrees of latitude, we believe to make ethe boring 
of ‘an artesian well a success, that we must select a point for that undertaking 
immediately east of the outcrop of the coal formation, or failing to find and iden- 
tify in any one spot the presence of the great lignite beds bordering the foot-hills, 
we must sink down through the great green clay deposit that overlies this forma- 
tion, until we reach the sandstone strata beneath it. For whenever the vertical 
boring in the coal formation reaches the sandstone and slates beneath the coal, 
we will find abundant supplies of water derived from the higher lands west of 
them. The same, but in a lessened degree, will be the case when we bore the 
great tertiary clay deposit overlying the coal measures unconformably. 
Now it has been shown from the result of the artesian well borings made by 
Captain Pope in the Zlano Estacado and also in New Mexico—by the borings 
made near Carson, in Arapahoe county, and also by one or two attempts made 
between the South Platte and the foot-hills near Golden—that although water was 
found in boring down in every instance, yet it signally faded to reach the surface 
by hydrostatic pressure. We believe this is due to two causes: 
1. That until such borings have been extended downward sufficiently to 
reach either the Tertiary clay, or cretaceous coal shales or clays, the fillets of 
water that are found are due either to local drainage, or— 
2. They are obtained from the scattered crevices or cleavage planes exist- 
ing everywhere in the porous sandstone and slates underlying the whole region 
embraced in our remarks—and that this universal diffusion of small underground 
veins, not derived from the higher mountains to the west, is the reason of their 
failure to reach the surface, or to overflow above it. 
We need not here allude to the well-known fact of the scarcity of springs 
