UPLIFT HEKE DUE TO DEPARTURE OF THE ICE. 521 



Late Glacial or Clianiplaiii subsidence to the resilience of the earth's crust 

 on account of the departure of the ice, the uplifting of northern Labrador 

 and of northern Greenland and Grinnell Land has been too great in verti- 

 cal extent to be proportionate with the probable thickness of the ice-sheet 

 on those areas. Their u})lifting has been in its greater part probably due 

 to a movement independent of glaciation. 



Epeirogenic movements of regions which have not been ice-covered 

 seem in some instances referable to a transfer of disturbances from glaciated 

 districts. Accompanying the subsidence of ice-loaded tracts, there were 

 doubtless uplifts of contiguous regions, perhaps sometimes including outer 

 portions of the country glaciated. For example, the upheaval of the St. 

 Elias range and of its foothills, found by Russell to have taken place sub- 

 sequent to a long and severe glaciation of that region,' may very probably 

 have been correlative with the Champlain subsidence ending the Glacial 

 period in the northern United States. 



UPLIFT OF THE BASIX OF LAKE AGASSIZ APPARENTLY ATTRIBUTA- 

 BLE WIIOLLY TO THE DEPARTURE OF TUE ICE-SIIEET. 



Within the basin of the glacial Lake Agassiz I believe that high pre- 

 glacial altitude, affecting likewise all the North American glaciated area, 

 was tenuinated by the depression of the land while it was ice-burdened. 

 All the movements which this basin has since experienced, as recorded by 

 the changes of levels of the beaches, seem to have resulted from the tend- 

 ency of the earth's crust to regain equilibrium, after the ice melted away, 

 by a moderate uplift, with inflow of the plastic or molten magma beneath. 

 The very regular gradation in the differential uplifting of the old shore- 

 lines, and its progress almost to completion while this lake was still held by 

 an ice barrier, accord well with this explanation. No element of epeiro- 

 genic disturbance is known here which is not readily accounted for by this 

 hypothesis. The explanation is found to be adequate and applicable to all 

 the features of the progressive changes in the levels of the l)eaches. The 

 very small component which could be ascribed to postglacial change in the 



' "Mount St. Elias and its glaciers," Am. Jour. .Sci. (3), Vol. XLIII, pp. 169-182, with map, March, 

 1892. 



