236 J. C. Branner — Paleozoic Sediments in Arkansas. 



In the Wahsatch section of Utah and Eastern Nevada the 

 Weber quartzite and its overlying Coal Measures and Permian 

 beds have a thickness of 10,650 and possibly of 16,650 feet.* 



In the Indian Territory Chance reports a thickness of 8500 

 to 10,000 feet in the Carboniferous rocks, but that is simply 

 another part of the Arkansas valley basin. f 



Thickness of Coal Measures [Pennsylvanian) Sediments in North 



America. 



Arkansas _ 23,780 



Nova Scotia 16,000 



Utah and Nevada _ 16,650 (?) 



Indian Territory 10,000 



In other parts of the Mississippi basin containing Coal Meas- 

 ures rocks the beds are generally less than 5000 feet thick, the 

 thicker portions lying along the eastern border of the Appa- 

 lachian coal fields from Pennsylvania to Alabama, where they 

 are 5500 feet thick. 



If we inquire into the reason for the great thickness of Coal 

 Measures sediment in the Arkansas Yalley, I believe it is to be 

 found in the drainage of the continent during Carboniferous 

 times. The rocks of this series in Arkansas contain occasional 

 marine fossils, and these marine beds alternate with brackish 

 or freshwater beds whose fossils are mostly ferns and such like 

 land or marsh plants. This part of the continent was, there- 

 fore, probably not much above tide level. The drainage from 

 near the Catskill Mountains in New York flowed south and 

 west. The eastern limit of the basin was somewhere near the 

 Archaean belt extending from New England to Central Ala- 

 bama. This Appalachian watershed crossed the present chan- 

 nel of the Mississippi from Central Alabama to the Ouachita 

 uplift, or to a watershed still farther south and now entirely 

 obliterated and buried in Northern Louisiana. In any case 

 the drainage flowed westward through what is now the 

 Arkansas valley between the Ozark Island on the north and 

 the Arkansas Island on the south. 



Acadian Geology, 2d ed., 1868, 149, 146, and 151), and still later 14,000 and 

 16,000 feet (Quar. Jour. Greol. Soc, xxx, 210). Mr. Gilpin says that H. 

 Fletclier of the Canadian Survey gives a total thickness of 21,960 feet for all the 

 Carboniferous of Cape Breton. This, however, includes the Lower Carboniferous 

 (Quar. Jour. Geol. Soc, xlii, 1886, p. 524). 



* U. S, Geol. Expl. 40th Parallel, I, Systematic Geology, by Clarence King, 

 pp 240, 248. 



f Trans. Amer. Inst. Mining Engineers, 1889-90, xviii, p. 655. 



