264 INDEX TO THE STEATIGRAPHY OF NOETH AMERICA. 



P 19. UNGAVA BAY. 



Akpatok Island, in Ungava Bay, is described by Robert Bell *^*'®^ as consisting 

 of a great thickness of "Cambro-Silurian" rocks. The fossils which he collected 

 are stated to represent the "Hudson River" terrane. 



According to Low,^^'"' the fossils of Akpatok Island range from "Lower Galena- 

 Trenton to Lower Helderberg." 



P-B 9-10. BEAR BIVEE, AND MACKENZIE VALLEY. 



Bear River, the outlet of Great Bear Lake, passes from Cretaceous to Paleozoic 

 rocks in cutting through a ridge of which Mount Charles is the highest point in the 

 vicinity. J. M. Bell ^*^ ascended the mountain in 1899 and reports: 



Ordovician of possibly Silurian rocks occur at "The Rapid" on the Bear River where the 

 mountain range crosses it. Mount Charles, the most prominent part of these mountains, is a 

 hiU of about 1,500 feet in height and consists of a large anticline, embracing subordinate folds. 

 The rocks are interstratified conglomerates, quartzites, and magnesian limestones, the latter of 

 great thickness. I found thin layers of gypsum in several places, interstratified with dark-gray 

 shaly dolomite. 



Bell does not cite any fossils. Dawson "^^""^ quotes Meek on the Devonian age 

 of the limestones of the Mackenzie Valley, which were earlier referred to the Silurian 

 by Isbister and others. "Amongst all the collections under examination from 

 various localities along Mackenzie River and its tributaries, between Clearwater 

 River and the Arctic Ocean, a distance by course of the valley of more than 1,000 

 miles, there are no Carboniferous or characteristic Silurian forms." If Bell and 

 Meek are both correct, the anticline crossed by Bear River brings up Silurian strata 

 not generally exposed along the Mackenzie. 



P-S 10-17. ARCTIC REGION. 



The southern islands of the Arctic Archipelago are extensively covered by 

 Silurian strata, probably in most places underlain by the late Ordovician, with 

 which they constitute the base of the stratified sediments that dip gently north- 

 ward from the "Laurentian" gneisses of the mainland. These Silurian deposits 

 are by their fossils so related to the strata occurring near Lake Winnipeg and in 

 the Mississippi Valley as to demonstrate the extent of the sea over northern central 

 North America. Waters affording the same habitat and supporting the same 

 faunas were continuous to the northern shores of Russia and spread widely over 

 Siberia.^''^'"^ 



Dawson's comments on the views formerly held and now deemed reasonable 

 as to the jpresence of Ordovician strata in the Arctic have already been quoted 

 (p. 222). The following account of the Silurian rocks is Haugh ton's description as 

 given by Dawson.^"' 



The Silurian rocks of the Arctic Archipelago rest everywhere directly on the granitoid 

 rocks, with a remarkable red sandstone, passing into a coarse grit, for their base. This sand- 

 stone is succeeded by a ferruginous limestone containing rounded particles of quartz, which 

 rapidly passes into a fine grayish-green earthy limestone abounding in fossils, and occasionally 

 into a chalky limestone, of a cream color, for the most part devoid of fossils. The average 

 dip of the Silurian limestone varies from 0° to 5° NNW., and it forms occasionally high cliffs 

 and occasionally low flat plains, terraced by the action of the ice as the ground rose from 



