214 THE DEVONIAN AND CARBONIFEROUS. [blul.80. 



thins out entirely south of the Eed Buttes on the North Platte. The 

 Carboniferous seemed to rest directly, though not conformably, upon 

 the metamorphic rocks. 



The conclusions drawn from the observations made were that all the 

 formations of the west undergo more or less change in both their min- 

 eral and fossil contents in their extension toward the west and south, 

 and that the Potsdam sandstone and Jurassic beds present more re- 

 markable changes than any of the others. 



In 1868 Mr. F. B. Meek examined several lots of fossils collected in 

 British America, some of which he found to be new ; these he described 

 and figured. Others he identified with already known fossils, and by 

 these correlated the formations in which they occurred with formations 

 in other parts of the country. The localities are on the Clearwater 

 River, near its mouth into the Athabasca ; on Laird's River, near Fort 

 Resolution ; on Slave Lake, and several localities along the Mackenzie 

 River Valley to old Fort Good Hope, and one locality on Porcupine 

 River. 



From the study of the fossils the following conclusions were reached: 

 That along the Mackenzie River and its tributaries, between the Clear- 

 water and the Arctic Ocean, " no Carboniferous or characteristic Silurian 

 formations are seen," and that there is " a continuous stretch of Devo- 

 nian rocks, mainly of the age of the Hamilton group, extending from 

 Rock Island, 111., in a northwesterly direction to the Arctic Ocean, a 

 distance in a right line of nearly 2,500 geographical miles." 



The great general similarity with frequent specific identity in the 

 faunas from the extreme ends of this line, the author considers, 

 "strongly corroborates the generally accepted opinion that climatic 

 conditions, if not uniform over the whole world, were at least little, if 

 at all, influenced by differences of latitude during paleozoic epochs." 1 



F. H. Bradley reported in 1872 2 the discovery of a few small trilo- 

 bites of Quebec group age, in the base of the mass of limestones over- 

 lying the central granites of the Teton Range in Idaho. These lime- 

 stones continue up to the typical Carboniferous. The Quebec group is 

 about 400 feet thick, partly argillaceous, blue, and mostly pebbly. 

 Above this group are 600 feet of a magnesian limestone, drab to buff 

 color, which Bradley correlated with the "cliff" limestone of the Mis- 

 sissippi Valley; and over this he found the true Carboniferous. 



In August, 1872, Professor Tenney 3 found corals in the Wahsatch 

 Mountains, southeast of Salt Lake City, in a dark bluish limestone, 

 nine or ten thousand feet above the sea. His own opinion that the 

 corals were Devonian was confirmed by R. P. Whitfield, who referred 



1 Meek, B. F.: Remarks on the geology of the valley of Mackenzie River, with figures and descriptions 

 of fossils, etc. Chicago Acad. Sci., Trans., vol. 1, 1869, pp. 61-114, and plates. 



2 Bradley, F. H. : On Quebec and Carboniferous rocks in the Teton Range. Am. Jour. Sci., 3d se- 

 ries, vol. 4, 1872, pp. 230, 231. 



'Tenney, Sanborne: On Devonian fossils in the Wahsatch Mountains. Am. Jour. Sci., 3d series, 

 vol. 5, 1873, pp. 139,) 40. 



