INDUSTRIAL PROGRESS DURING THE YEAR 1876. Ixxxi:: 



GEOLOGY. 



By T. STEHRY hunt, LL.D., F.E.S., 



Professor of Geology, Massachusetts Institute of Technology, Boston. 



The Geological explorations wliicli, under the authority of the 

 United States government, have been going on for the last few years 

 in the western part of our territory, have reached a point where it 

 becomes possible to generalize the observations. 



GEOLOGY OF THE FORTIETH PARALLEL. 



Clarence King has given us, in anticipation of his published vol- 

 ume, an important contribution to the history of the Paleozoic series 

 as displayed along a belt of about one hundred miles in breadth, 

 following the 40th and 41st parallels of latitude from the 104th to 

 the 120th meridian, or from the eastern base of the Rocky Mountains 

 to the confines of California. By a careful study of the outcrops and 

 of their organic remains, he and his assistants have been able to 

 make out the succession, and to correlate the various divisions with 

 the New York series of rocks. The Paleozoic strata of the eastern 

 half of the continent, generally estimated at 40,000 feet in Pennsyl- 

 vania, arc diminished to about one tenth of that thickness on the 

 Mississippi ; and in the eastern part of the Rocky Mountains have a 

 total thickness of not more than from 900 to 1200 feet, including at 

 the base Cambrian, and at the summit Carboniferous strata ; the whole 

 forming apparently one conformable sequence, which rests in dis- 

 cordance upon crystalline rocks of Eozoic age. This Paleozoic series 

 rapidly thickens westward to a volume of not less than 32,000 feet 

 in Utah ; and many divisions not recognized in the eastern part of 

 the region under consideration are developed with great force and 

 persistence in Utah and Nevada. Near Battle Mountain, however 

 (longitude 117 25'), the Paleozoic series is interrupted by a barrier 

 of Eozoic rocks. The Rocky Mountain region was in Paleozoic time 

 a shallow sea, with islands of Eozoic rock, while, beyond, the ocean 

 deepened over a great basin to the western shore. 



THE WAHSATCH SECTION. 



In the Wahsatch range a single section is seen 30,000 feet in thick- 

 ness, including Lower Cambrian, and extending through Silurian, 

 Devonian, Carboniferous, and Permian, which latter is overlaid by 

 Trias; the whole succession being without any observable strati- 

 graphical break. The base of this great conformable series consists 



