512 THE GLACIAL LAKE AGASSIZ. 



than uow, giving to this brackish body of water a considerably liigher 

 degree of saltness than at present, with the admission of several marine 

 inollusks, notably Litorina litorea Menke, which are found fossil in the beds 

 formed during this second and smaller submergence, but are not living in 

 the Baltic to-day. Thus for the moveilients of southern Sweden are par- 

 alleled by the postglacial oscillations of New England and eastern Canada; 

 but a second uplifting of this part of Sweden is uow taking place, whereas 

 no corresjjonding mo^'ement has begun on our Atlantic border. It seems 

 to be suggested, however, that it may yet ensue. The subsidence has 

 ceased or become exceedingly slow in eastern New England, while it still 

 continues at a measurable rate in New Jersej^, in Cape Breton Island, and 

 in southern Greenland. 



So extensive agreement on opposite sides of the Atlantic, and also in 

 Patagonia, in tlie oscillations of the land Avhile it was ice-covered and since 

 the departure of the ice-sheets, has probably resulted from similar causes, 

 namely, the })ressure of the ice weight and resilience of the earth's crust 

 when it was unbm-dened. The restoration of isostatic eqiiilibrium in both 

 North America, and Europe is attended by minor oscillations, the conditions 

 requisite for repose being overpassed by the early reelevation of outer por- 

 tions of each of these great glaciated areas. 



In view of this harmony in the epeirogenic movements of the two 

 continents dunug the Glacial and Recent periods, it seems evident that the 

 close of the Ice age was not geologically long ago, for eqiiilibrium of 

 the disturbed areas has not yet been restored. Furthermore, the parallelism 

 in the stages of progress toward repose indicates nearly the same time for 

 the end of the Glacial period on both continents, and approximate syn- 

 clu'onism in the pendulum-like series of postglacial oscillations. 



PLEISTOCENE OSCILLATIONS INDEPENDENT OF GLACIATION. 



In this class of changes are to be included, wholly or in part, the post- 

 glacial elevation of Grinnell Land and the noi'thwestern coast of Greenhuid, 

 1,000 to 2,000 feet;' post-Pliocene upward movements of 2,000 feet or 



' Quart. .lour. Geol. Soc, Vol. XXXIV, 1878, iip. 66 and 566. Gool. Mag. (3), Vol. I, 1884, p. 522. 

 A. W. Greely, Report of the U. S. Expedition to Lady Franklin Bay, Grinnell Land, Vol. II, 1888, p. 57. 



