an ee aa 
Esmeralda County, Nevada.—Turner, 265 
those nearest the base being large forms of Olenellus with 
some smaller species. The rock forming this lowest Olenel- 
lus zone is a dark micaceous slate. Higher up are layers of 
dark limestone with some quartzyte, the limestone being often 
crowded with little orbicular bodies, somewhat resembling 
Stromatopora, but which are not certainly of organic origin. 
Then comes a second Olenellus zone, composed of green 
slate, again succeeded by fossiliferous limestone. 
In the Silver Peak range the basal dolomyte, and quartzyte 
if present, does not show such a great thickness as elsewhere. 
The basal member of the Lower Cambrian here is at most 
points a dolomyte, resting directly on the basement complex, 
but this dolomyte may not correspond to the basal dolomyte of 
the section north of Clayton valley. 
Upper Cambrian. Lying unconformably on the Lower 
Cainbrian or Silver Peak formation, is a series of thin bedded 
limestones, and reddish slates with some layers of black chert. 
This series may be designated ‘The Emigrant formation,’ 
since it is finely developed to the south of Emigrant Pass in 
the northern part of the Silver Peak range. In this formation 
are abundant little disk-shaped shells, (linguloids) fragments 
ot phyllopods (Phyllocarida), and some corals and trilobites. 
The shells are in an excellent state of preservation. These 
fossils are regarded by Mr. C. D. Walcott as indicating an 
Upper Cambrian age.* They appear to conformably underlie 
the cherts and slates of the Palmetto formation which is chief- 
ly characterized by graptolite remains. Moreover, the phyllo- 
pods, so commor in the Upper Cambrian, are found imbedded 
with slate containing graptolites at the base of the Palmetto 
formation, and the little disk-shaped shells (linguloids) were 
found in the slate but a few feet under the graptolite slate with 
no evident unconformity, so that there appears to be no sharp 
line of separation between the Emigrant formation of Upper 
Cambrian, and the Palmetto formation forming the base of the 
_ Ordovician. 
Ordovician. At many points in the Silver Peak range, in 
the ’almette mountains, in the ranges north of Clayton valley, 
* In my paper on the Esmeraldaformation in the AMERICAN GEOLOGIST, 
Vol. XXV, 1900, and in the 21st Annual Report of the U. S. Geol. Survey, this 
series of rocks is said to be of Middle Cambrian age. Later investigation 
based on more material has convinced Mr. Walcott, that they are of Upper 
Cambrian age. 
