100 GEOLOGY. 
stated, at ‘‘ Campbell’s Pass,’’ where we crossed it, no mountains whatever are visible, except 
the distant and isolated volcanic cone of Mount Taylor. 
The great mass of the mountains at Santa Fé is made up of a red coarse granite, traversed by 
numerous veins of quartz, some of which are metalliferous, containing silver, gold, copper, and 
lead. 
On the flanks of this igneous axis the limestone of the Carboniferous series is frequently seen 
resting, usually but little metamorphosed. Over the limestone, sometimes in concordant, some- 
times in discordant stratification, are such portions of the red sandstones, variegated marls, 
and Cretaceous rocks, as have been spared by tlie erosion they have suffered. 
The Carboniferous limestone at Santa Fé is dark bluish-brown in color, and very hard. It 
contains great numbers of fossils, for the most part of species common in the coal measures of 
the Mississippi valley, though a few are new. The most common are Productus scabriculus, P. 
Rogersi, P. semireticulatus, P. nodosus, (n. sp.,) Spirigera subtilita, Spirifer cameratus, ete. 
At various localities in the vicinity of Santa Fé Carboniferous shales are interstratified with 
the limestone, and contain fossil plants characteristic of the Coal measures. From these facts, 
as well as those before cited, it will be seen that the limestone of this region—called Lower 
Carboniferous or ‘‘ Mountain’’ limestone by Mr. Marcou—is the equivalent of the Coal measures. 
As we approached the Mississippi on our homeward journey, we were able to trace the changes 
which take place in the lithological character of the Coal measures from the series of the sand- 
stones, shales, limestones, fire clays, coal, &c., forming the productive Coal measures to the 
massive and nearly homogeneous limestone of the southwest. 
Specimens of excellent anthracite coal were given me by Mr. Mercure, obtained at the ‘‘ Old 
placer,’’ where it occurs in a stratum of workable thickness. Whether it is of Carboniferous 
age or not I had no means of determining. I regretted that I was unable to visit a locality of 
so much economical and scientific interest as that which furnishes it. 
The fact which has already been referred to, that the limestone of this vicinity rests directly 
on the granite, and that it is so little changed by that contact, indicates that these granitic 
masses had an existence before the Carboniferous epoch; that the limestone was deposited upon 
them, and that since that period, though greatly elevated, they have not been fused. 
The great mass of sedimentary rocks which underlie the Coal measure limestone, in the cafion 
of the Colorado, is here apparently wanting, for I have seen nothing I could imagine to repre- 
sent them even in any metamorphic form. This fact seems to teach that some of the ranges of 
the Rocky mountains had representatives at a very early period, forming limits which restricted 
the deposition of the older palzozoic rocks, and that their summits were only covered by sedi- 
ments during the Carboniferous era. 
It will be seen that in the preceding sketch of the geology of the country west of the Rio 
Grande, bordering our route, I have failed to recognize the Jurassic formation in any of the 
localities where it has been said to occur; and that I have regarded the yellow sandstones, 
green, gray, and blue shales, &c., called Jurassic by a recent writer, as of Cretaceousage. The 
evidence of the accuracy of this determination is, I think, incontrovertible. These strata were 
traced by us almost without interruption from the Moqui country to the Rio Grande, and there 
is scarcely room for error even if we had no other guide than this continuity, their relations to 
the associated rocks, and their lithological characters. In addition to these, however, we found 
at the Moqui villages abundant fossils of unequivocal Cretaceous character in them, and a suffi- 
cient number of those called such by our best paleontologists (Messrs. Hall, Shumard, and 
Meek) at various other points along our route, to furnish all necessary paleontological proof 
-—_of their identity. | 
- 8 is not asserted that Jurassic rocks do not exist in this region, for it is possible, and per- 
_- haps probable, that they do, but only that those called such on that portion of our route passed 
_ over by Mr. Marcou are Cretaceous. 
