ACADEMY OF NATURAL SCIENCES. 269 



At two or three points within this Triassic area there are indications of the 

 existence of fossiliferous rocks occupying a higher position than the Trias, and 

 perhaps of Liassic Age ; but the collections have not yet been sufficiently studied 

 to justify a positive opinion on this point. 



The sedimentary strata in this region are much broken up and metamor- 

 phosed by intrusive rocks, of which there is a great variety, granite being one 

 of the most abundant. In the southern portion of the area designated above 

 as including stratified rocks of Triassic age, a very large part of the surface is 

 occupied by volcanic materials, apparently a continuation of the very recent 

 volcanic masses near Mono Lake. Lava is said to be the predominating rock 

 over the region to the southeast of Walker's Lake, and as far in that direction 

 as the State line between Nevada and Arizona. The same is true of the 

 region to the north and northwest of Humboldt Kiver, where granitic and 

 volcanic rocks are reported as occurring, and where, so far as known, no fossils 

 have yet been obtained. This, however, is a region as yet but little explored, 

 on account of the number and warlike disposition of the Indians. 



Between the 116th and 117th meridians is a region of granitic and volcanic 

 rocks, including two principal north and south ranges, and many spurs and side 

 ranges. The Toiyabe range, in which are the mines of Austin, or the Reese 

 River mines, and which is a little east of the 117th meridian, is mostly granitic. 

 Stratified but highly metamorphosed rocks are said by Mr. Blatchley to occur 

 on its east flank, a few miles south of Austin ; these rocks contain fossils, 

 which, however, are nearly obliterated by metamorphism. A box of these, 

 forwarded some time since, has never been received, so that no positive state- 

 ment can be made as to the age of the formation. From Mr. Blatchley 's 

 description of the forms observed by him, it would appear that we may have 

 here rocks older than the Carboniferous. 



East of the 116th meridian, our collections indicate the existence of a broad 

 area covered chiefly by rocks of Carboniferous age, which seem to occupy 

 most of the space between the 115th and 116th meridians. The most western 

 locality of Carboniferous fossils known to us is that on the west side of Diamond 

 Yalley, about 70 miles east of Austin, and in Ion. 116°. Here, in a dark, 

 crystalline limestone, a variety of species have been obtained by Mr. Clayton, 

 all in a poor state of preservation, but of which the Carboniferous age may be 

 without difficulty made out, Among the genera represented at this locality are 

 Productus — two species, one of which is P. semireticulatus — Spirifer, aud 

 Fusulina, probably F. gracilis, besides some indistinctly marked corals. The 

 indications are that these beds are of Lower Carboniferous age. On the east 

 side of Diamond Valley some imperfectly preserved corals have been found, 

 probably Devonian, or possibly belonging to a still older group. The collections 

 from the region included between the 115th and 116th meridians indicate the 

 association of rocks of both Devonian and Carboniferous age in the outcrops. 

 Here our collections do not enable us to do anything more than to corroborate 

 the previously published statements of Messrs. Meek and Engelmann in regard 

 to the age of the formations. 



From the Silver Peak District, near Ion. 117° 20', and lat. 38°, an interest- 



