306 B. Chalmers — Pleistocene Marine Shore-Lines 



The shore-lines above described face the open St. Lawrence 

 valley, either where it is now occupied by the sea, or has been 

 occupied by it during the Pleistocene period. 



No fossils have yet been detected in the terraces, though 

 they have been found in a number of places in the marine 

 plain of which the terraces or shore-lines form the margin. 

 "Very little search for fossils has, however, been made in them. 



The Chaudiere and St. Francis rivers intersect the mountain 

 range, along the north side of which the shore-lines have been 

 traced, by valleys as low as the marine plain along the St. 

 Lawrence River. During the Pleistocene subsidence the sea 

 invaded these valleys, and shore-lines are, therefore, found 

 along the banks at the present day. Not only the main val- 

 leys of the Chaudiere and St. Francis have been thus occupied 

 by the sea, but a wide extent of country to the southeast of 

 the mountains referred to was also overflowed (unless the rela- 

 tive levels were wholly different then from what they are now), 

 and apparently formed estuaries in which thick deposits of 

 stratified sand, gravel and clay were laid down. 



Following the valley of the Chaudiere southward from Ste. 

 Marie we find shore-lines in numerous places — one of these on 

 the west side opposite the village of St. Francois, being at a 

 height of 870 to 875 feet. Another occurs seven or eight 

 miles above the confluence of the Du Loup and Chaudiere 

 rivers. Here an extensive terrace spreads out in the valley of 

 the latter river which I was informed extended across the 

 country to the Du Loup valley. Prof. J. W. Spencer and I 

 examined this, terrace together. In the valley of the Chaudiere 

 it is 870 to 875 feet high : in the Du Loup valley near St. 

 Come it is slightly higher, being 890 to 900 feet. 



In the drainage basin of the St. Francis River, terraces were 

 observed which seem to be related to the shore-lines on the 

 northwest side of the intervening mountains and correspond 

 with them in altitude. One of these stretches along the south- 

 eastern base of Dudswell Mountain for five or six miles, facing 

 a great valley to the south, through which the St. Francis 

 River flows. Its height is from 840 to 850 feet. 



At the north end of Lake Memphremagog, and extending 

 towards the base of Orford Mountain, terraces occur composed 

 of gravel, sand and clay, resembling the Saxicava sand and 

 Leda clay of the St. Lawrence Valley. Fossils have not yet 

 been found in these deposits, but no thorough search has been 

 made for them. The height of the terraces is from 860 to 865 

 feet. A valley of considerable width extends from the north 

 end of Lake Memphremagog along the course of its outlet — 

 the Magog River — by Little Magog Lake, thence to the main 

 valley of the St. Francis River. Through this valley the sea 



