Sea-Cliff of the Lower Saint Lawrence. 317 



effective than it actually is at the present time. This, how- 

 ever, is not a valid argument, because the waves are now work- 

 ing on the outer, natter portion of the Micmac shelf. Even if 

 this shelf is now slowly sinking, wave action will be seriously 

 hindered by the shallow water, until, with continued coastal 

 subsidence, the sea again stands as high as the foot of the old 

 cliffs. 



Conclusion. 



The elevation of the Lower Saint Lawrence Valley from the 

 sea to its present position appears to be divisible into three 

 stages. The first stage consisted in a differential upwarping of 

 the region. Beginning no later than the withdrawal of the ice 

 from the estuary, the uplift continued without interruption 

 until the original Champlain beach stood from about 1Y0 feet 

 above the sea at Matane to about 630 feet above the sea at 

 Quebec. Toward the close of this stage, the rate of uplift 

 probably decreased, until it ceased altogether. The second 

 stage, marked by the great Micmac terrace and sea-cliff, may 

 have been an interval of stability, in which case it lasted some 

 3,000 years. More probably it was a stage of slow subsidence, 

 of shorter duration, in which cliff cutting w r as accelerated, 

 although the vertical amount of subsidence was not great. 

 This Micmac stage is tentatively referred to that stage when 

 forests were submerged, along the coast of Acadia and New 

 England. Following the development of the Micmac terrace 

 and cliff, the coast of the Lower Saint Lawrence rose, evenly, 

 and slowly, to its present position. With existing data it is 

 impossible to tell whether this movement is still in progress, 

 or has ceased, or has been followed by minor oscillations. 



While these conclusions rest primarily upon evidence in 

 Canada, and especially upon newly collected data from the 

 Lower Saint Lawrence, they are supported in part by a com- 

 parison with the conclusions of Professor Broegger, Baron 

 De Geer, and others who have investigated the raised beaches 

 of Scandinavia. Although it is expected that the post-glacial 

 movements in these two regions on opposite sides of the 

 Atlantic will prove to be alike in all respects, as more accurate 

 and exhaustive studies are made in Canada and New England, 

 the recognition of the Micmac shoreline as a record of one — 

 and apparently the only — pronounced interruption in the 

 emergence of the coast, in southern Quebec, points to a closer 

 similarity of movements in Scandinavia and in Canada, than 

 has heretofore been supposed. 



Dartmouth College, Hanover, N. H., 

 July, 1911. 



Am. Jour. Sci.— Fourth Series, Vol. XXXII, No. 190.— October, 1911. 

 23 



