INDUSTEIAL PROGRESS DURING THE YEAR 1873. xlv 



ward, and consisting at the base of from 1000 to 1500 feet of 

 quartzites and conglomerates, regarded as of Potsdam age, 

 follovred bv 3000 feet of magrnesian limestones and calcare- 

 ous shales, which afibrd numerous organic forms about the 

 age of the Calciferous and Chazy divisions of the New York 

 system. These correspond to the Levis division of the so- 

 called Quebec group, or the Auroral of Rogers, Mr. Meek hav- 

 ing recognized therein many of the forms so well described 

 by Billings from the vicinity of Quebec. Toward the sum- 

 mit of this fossiliferous series forms referred to the Niagara 

 have been recognized, and in some of them, according to Ten- 

 ney, corals of Lower Helderberg age. Above these are 2000 

 feet of sandstones, probably Devonian, followed by 3000 feet 

 of limestones abounding in the remains of the Carboniferous 

 period. We find no notice in this region of the existence of 

 the second fauna, corresponding to the Trenton, Utica, and 

 Hudson River rocks of New York, the Matinal of Rogers, 

 the Upper Cambrian of Sedgwick, or Siluro-Cambrian. In 

 the apparent absence of these Siluro-Cambrian rocks, which 

 are widely spread throughout the great North American 

 })aleozoic basin, we see a resemblance to northeastern Amer- 

 ica where, also, the rocks of the first and third paleozoic faunas 

 occur to the exclusion of the second fauna. This great thick- 

 ness of paleozoic strata is not every where seen in this re- 

 gion, since, according to Mr. Bradley, in the Teton Mountains 

 the Avhole of the Cambrian rocks arc represented by 700 feet 

 of quartzites and shaly limestones, overlaid by 600 feet of 

 vesicular magnesian limestones with crinoids, probably of 

 Niao-ara aire, which are followed in their turn by the same 

 Carboniferous limestones as before, with a thickness of 2000 

 feet or more. Although the Levis limestones are generally 

 conformable with the Potsdam sandstone in this region, 

 they are in one place seen to rest unconformably upon the 

 upturned sandstone. In western Wyoming, Professor T. B. 

 Comstock, the geologist to the late expedition under General 

 Ord, shows in the Wind River Mountains a remarkable se- 

 ries, all apparently conformable, and resting at an angle of 

 about 20 upon the older crystalline rocks. At the base are 

 Lower Cambrian rocks, followed by strata with Oriskany fos- 

 sils, and by Carboniferous limestones. Above these are bright 

 red Triassic sandstones, lighter red Jurassic rocks, and Cre- 



