Review of Recent Geological Literature. 183 
■western limit being a line drawn from north to south not far west of 
Minneapolis and Mankato. The formations classed as Upper Cambrian 
attain a thickness of nearly 2,000 feet, while the Lower Silurian 
measures only about 450 feet. No Upper Silurian rocks are found; but 
a few feet of early Devonian beds occur in the south edge of the state. 
The Trenton and Galena limestones and shales are subdivided into ten 
beds, distinguished partly by lithologic but chiefly by paleontologic 
characters Lists of the fossils observed in each of these beds, and in 
the other formations below and above the Trenton series, are noted. The 
authors extend the Cambrian upward to include the Lower Magnesiaa 
or Shakopee limestone, which is regarded by VValcott as the base of the- 
Silurian. 
Geology of the Taylorville Region of California. By J. S. Diller.. 
Bulletin, G. S. A., Vol. iii, pp. 369-394, with nine figures of sections in 
the text; July 15, 1892. The area here described is about twelve miles- 
long and six miles wide, Ij'ing in the northern part of the Sierra Nevada, 
mountain belt, immediately north of the fortieth parallel. Mt. Jura,, 
near the center of this area, is so named because of its fossiliferous 
Jurassic rocks. The exposed sedimentary series has a total thickness of 
24,500 feet; of which 17,500 feet are probably Paleozoic, and 7,000 feet. 
are Mesozoic strata. The latter comprise at least three formations in, 
the Trias, and five in the Jura, definitely recognized by fossils. Erup- 
tive rocks are also present in great variety, their epochs of extravasa- 
tion being successively early Paleozoic, Triassic, at the close of the- 
Jurassic, and finally Neocene and Pleistocene. The region was covered' 
by the sea during most of its history, until the end of the Jura period, 
when a great upheaval formed land along the present Sierra Nevada belt 
Jura and Trias at Taylorville, California. By Alpheus Hyatt. Bul- 
letin, G. 6. A., Vol. Ill, pp. 395-412; July 15, 1892. Professor Hyatt in 
this paper gives preliminary descriptions and discussion of the rich, 
faunas, of early and middle Mesozoic age, which have been collected in. 
the strata of Mt. Jura and other parts of the area described by Mr. Dil- 
ler in the preceding paper. The Jurassic formations, in ascending 
order, are the Hargrave sandstone, referred to the Upper Lias of Europe;: 
the Thompson limestone and Mormon sandstone regarded as equivalent 
with the inferior Oolite; and the Bicknell sandstone and Hinchman tuff,, 
respectively representing the Callovian and Corallian faunas of the 
European Upper Jura or Malm. The Jurassic system is more fully 
recognizable here than in any other known locality in the United States. 
The Geological Map of the United States, and the United. States Geological 
Survey. Julus Marcou. Cambridge, Mass. April, 1892. 8vo, pp. 56» 
This is a caustic review and criticism of the United States Geological. 
Survey, its organization, work, personnel, and its relations to the pro- 
gress of geology in America. Mr. Marcou's style of direct and severe- 
criticism is a marked characteristic of this pamphlet, and his well-knowa 
fearless manner of exposing what he is convinced is wrong, is apparent 
in every line. His life has been spent as an "indjependent geologist,"* 
