128 THE GLACIAL LAKE AGASSIZ. 



leys which lead southward Avithin the glaciated region or on its southern 

 border; and postglacial time, extending to the present day, is therefore 

 named by Dana the Recent or Terrace epoch. It is to be remarked, how- 

 ever, that much of the terracing of the valley di'ift was doubtless done 

 speedily after the retreat of the ice from any basin, while yet adjacent 

 di'ainage areas on the north were receiving from it thick flood-plain depos- 

 its. The Glacial, Champlain, and Terrace epochs thus overlap, the second 

 being wholly and the third partially included within the Glacial or Pleis- 

 tocene period, if continental areas are considered; but for any limited 

 district, as a single river basin, the sculpturing- of the terraces took place 

 chiefly after the departure of the ice beyond its watershed. 



Latest glaciation far north. — In the latest stages of the glacial recession 

 the ice-sheet probably became diAaded into three remnants, one covering 

 northern British Columbia and contiguous portions of the Northwest Terri- 

 tory and Alaska, another occupying the region west, northwest, and north 

 of Hudson Bay, stretching- northward to the large islands of the Arctic 

 Ocean, and a third covering Labrador and the country north of the St. 

 Lawrence. The present glaciers of British Columbia and southern Alaska, 

 the broad Malaspina glacier or ice-sheet, described by Russell, between the 

 St. Elias Range and the ocean, and the extensive ice-enveloped country 

 seen by Russell in the view northward from Mount St. Elias, estimated by 

 him to embrace not less than 30,000 square miles, are surAaA-ing repre- 

 sentatives of glaciation which probably has been continuous in that region 

 since the time of maximum extent and depth of the continental ice-sheet.^ 

 From the second of these areas glacial currents moved south-southwest- 

 wardly across the Churchill River and Reindeer and Athabasca lakes, 

 partly obliterating the earlier westward stri.i?, and southeastwardly across 

 Marble Island, in the northwestern part of Hudson Bay. This division of 

 the North Ameiican ice-sheet is probably still represented by glaciers or a 

 small ice-sheet in Baffin Land, on the coast of Fox Channel, from which 

 its icebergs are carried southeastward into Hudson Strait.^ Possibly the 



' National Geographic Magazine, Vol. Ill, pp. 53-203, with 19 plates, May 29, 1891. Am. Jour. 

 Sci. (3), Vol. XLIII, pp. 169-182, with map, March. 1892. Am. Geologist, Vol. IX, pp. 322-336, May, 1892. 



2 Dr. Robert Bell, Geol. and Nat. Hist. Survey of Canada, Report of Progress for 1882-83-84, 

 p. 24 DD. 



