ease, eee 
wes 
ta ae 
Pe ee ee ee TS Soe ee en a ene ase ee te ere Lee To 
EP a ee et 
Ds ea oe 
See EEE AUREL Nee SF PO et 
C. A. White—Jura-Trias of North America. 215 
very generally referred to the Trias. It is my present purpose 
‘emarks upon these western Mesozoic formations, 
but not now to consider those strata which are commonly re- 
ferred to the Triassic period in Connecticut and certain 
Atlantic States farther south. 
ome modification of the views concerning these western 
formations that have been just indicated was produced, but the 
elucidation of the question of actual synchronism of these two 
groups with European strata hardly advanced by the following 
circumstances. The sandstone formation before referred to, 
that great region east of western Nevada, and beneath the 
akota group of the Cretaceons series belong to one and the 
same epoch. The impression however still prevailing that the 
Triassic period, at least in part, is really represented by the 
existence of these strata was first made known in 1864, by the 
publication of volume I, Paleontology of California; and the 
were still further described in the lately published volumes of 
the United States Geological Exploration, 40th Parallel. In both 
a : owstone and Missouri Rivers. By F. V. 
Baer, Gane Be eauce bey oh ¥, F. Raynolds, Corps of Engineers U. 8. A. 
Made in 1860 and published in 1869. 8vo, pamphle 
e White’s paleontological chapter in Powell’s Report on the Geology of the 
Uinta Mountains, pages 80 and 87. 
. Jour. Sct,.—Tuirp gers Vou. XVII, No. 99.—Marcu, 1879. 
1 
