PHYSICAL AND FAUNAL EVOLUTION 
appearance of the Ogden quartzite 
and conglomerate, which bears inter- 
ee é 
nal evidence of continental, chiefly i ie g 
river, origin; and to all appearance Hit}: : 
represents the sand and gravel wash L : : 
which followed the retreating sea H; ‘ 2 
westward, and which was probably in ols = 
large part derived from the basal Uinta | {2 i : 
quartzites, with which the Ogden seems 
to become confluent in the eastern | |//IH} 
Wintas.>  Vhis quartzite rests. on F 
higher beds in the western sections [{] |i 
than in the eastern, thus showing the 
same relationship to the underlying 
series that is exhibited by the St. 
Reter- sandstone. ,- In the “western. |; 
= 
T 
= — 
——— = 
Jintas it is underlain by 1,200 feet 
of shales, regarded as Cambric, though 
Van) ane 
=— 
1 ain == 
—— 
the highest beds may represent the 
Lower Ordovicic. In the Wasatch 
Mountains the Ute limestone, 2,000 
feet thick, and of Cambro-Ordovicic 
age, lies between the Ogden and Uinta 
quartzites. In the Eureka section of 
central Nevada, the Pogonip limestone, 
2,700 feet thick, underlies the Eureka 
quartzite, the westward continuation “ih 
of the Ogden. The Pogonip repre- i 
sents, in its basal portion, the transi- i 
tion beds from the Upper Cambric, 
but corresponds mostly to the Beek- 
mantown of eastern North America. 1 | 
Beneath it are 6,200 feet of fossiliferous i | 
shales and limestones of Cambric age. i aM > 
Here, as in the eastern region, succes- a AN 
WAN i 
t Berkey, Bull. Geol. Soc. Amer., Vol. XVI, chat 
H : 
PP: 517739: 
Fig. 6.—Diagram showing the relationships and overlaps of the Paleozoic strata west of the Rocky Mountains. 
