TRIASSIC ROCKS OF NEW MEXICO. 101 
Nor is it claimed that the Trias is not here represented. So far is that from the truth that 
the writer has little doubt that strata many hundred feet in thickness, intervening between the 
Carboniferous and Cretaceous formations, are the equivalents of Triassic rocks of Europe, and 
that at some future day the evidence of identity, which up to the present time has not been 
discovered, will be supplied. At the same time, that the subdivisions of the European Trias, 
the ‘‘ Bunter Sandstein,’’ the ‘* Muschelkalk,’’ and the ‘‘ Keuper,’’ will ever be fully identified 
in New Mexico, I regard as doubtful. 
The aggregate thickness assigned to the rocks filling the space between the Chalk and the 
Coal series in the preceding pages is, as will have been noticed, considerably less than the 
estimates before published. A part of the discrepancy will be accounted for by my bringing. 
down the Cretaceous system so as to include all the Jurassic rocks of Mr. Marcou; but, excluding 
these, the red sandstones and variegated marls, called Triassic by Mr. Marcou, are said by him to 
have a thickness of 5,000 to 6,000 feet, (Geology of North America, pp. 10, 11, 12,) while in all of our 
measurements of the splendid sections of these strata, in the Painted Desert and Moqui country, 
we found an aggregate thickness of about 2,000 feet; and on the Rio Grande the same geo- 
logical interval is several hundred feet less. i 
It is true that the eye, in a region where the atmosphere is so pure, and the reach of vision 
so great, where all the physical features are on so grand a scale, is a very unsafe guide, and 
will continually lead to under estimates ; but we made constant use of the barometer, and em- 
ployed the observations on the same strata at different points as checks on each other. I am 
very sure that in attributing a maximum thickness of 2,500 feet to the Triassic formation of Mr, 
Marcou its relative importance has not been underrated. 
