on the South Side of the St. Lawrence Valley. 303 



St. Lawrence Valley, as stated, and will, if possible, be con- 

 tinued until the International boundary is again reached in the 

 neighborhood of Lake Champlain. The following notes on 

 the salient features of these high-level shore-lines, though 

 incomplete, are offered meantime in the hope that they may be 

 of interest to students of Pleistocene geology. 



Topographic features of the region on the south side of the 

 St. Lawrence Liiver. — The border of the highlands or moun- 

 tainous country called the Notre Dame Range, extending from 

 the extremity of the Gaspe peninsula to the International 

 boundary in the State of Vermont, runs close to the St. Law- 

 rence as far west as Kamouraska. Thence it gradually 

 recedes from the river as we proceed westward and near Lake 

 Champlain is not less than forty or fifty miles distant from the 

 St. Lawrence River. The elevation of these mountains is from 

 1,500 feet to 2,000 or 2,500 feet, the central range being of 

 course the highest. Though intersected in a few places by 

 rivers, as, for example, by the Ste. Anne des Monts, the Chau- 

 diere and St. Francis, the mountains, nevertheless, present a 

 gradually ascending slope, rising from the marine plain of the 

 St. Lawrence Valley, of almost unbroken continuity throughout 

 their whole length. Along the foot of the range lower ridges 

 extend parallel thereto, especially below Quebec, which, how- 

 ever, become more and more broken and of less altitude as we 

 leave the higher grounds and approach the shore of the river. 

 Above Quebec a considerable breadth of low-lying country 

 intervenes between the mountains and the St. Lawrence, 

 described below, in which few elevations occur. 



The marine plain on the south side of the St. Lawrence 

 Valley. — A large portion of the great marine plain of the St. 

 Lawrence Valley lies on the south side of the St. Lawrence 

 River, i. e. between it and the northern base of the Notre Dame 

 Range (the low-lying country referred to above being a part of 

 it). This part of the plain extends continuously along the 

 whole valley, with hills and ridges, often isolated, rising here 

 and there which relieve the monotony. Along the lower St. 

 Lawrence it is comparatively narrow, in some places forming 

 merely benches ; but it widens as we ascend the valley. At 

 Kamouraska it is from half a mile to two or three miles in 

 width; at Montmagny from two to five miles; at Levis it is 

 not less than fifteen miles wide ; at Ste. Henedine and the 

 mouth of the Chaudiere River the width is about twenty miles, 

 and at Ste. Julie and Somerset stations, Grand Trunk Railway, 

 twenty-five miles or upwards. Between South Somerset and 

 the International boundary it is from forty to fifty miles in 

 width. The deposits constituting the plain are Saxicava sand, 

 Leda clay and bowlder-clay with some residuary material 



