on the South Side of the St. Lawrence Valley. 307 



could easily have reached the basin of Lake Mem phrem agog 

 during the later Pleistocene subsidence, if the relative levels 

 then were not entirely different from what they are at the 

 present day. Thick deposits of stratified sand, gravel and clay 

 occur along this valley ; but I have not had time yet to examine 

 them for fossils. Many years ago fragments of shells were 

 found in this valley near Little Magog Lake which were 

 reported on by Dr. T. Sterry Hunt as follows: "It is worthy 

 of record that on Lot 6, Range XIY, of Ascot, Mr. A. Michel 

 detected shells in clay beds which were too imperfect to be 

 preserved, but from a drawing made on the spot appear to be 

 a species of Mya."* 



Terraces and plains occupying higher levels than those 

 described were observed along the Quebec Central Railway 

 about the headwaters of St. Francis River, also on the divide 

 between these and the Chaudiere waters. Between Tring and 

 Robertson stations one was seen at a height of about 1040 feet. 

 At the west end of Lake Aylmer another occurs at about 1075 

 feet. These were at first supposed to be lacustrine, but there 

 seem to be no barriers which could have held in lakes at these 

 levels. The terrace at Lake Aylmer is apparently continuous 

 with other terraces or plains surrounding several of the lakes 

 in this vicinity. If these terraces are marine they indicate a 

 greater differential uplift of this portion of the country — a 

 theory which was broached on a previous page, — but in the 

 absence of fossils and of detailed examination no positive con- 

 clusion can be reached concerning them. 



In the valley of the Coaticooke River high-level terraces 

 were also observed. These appear, however, to be bounded by 

 the sides of the valley and enclosed in longitudinal basins, nar- 

 row at both ends, and sometimes end on to each other. The 

 height of one at Coaticooke station, Grand Trunk Railway, is 

 about 1210 feet, and of another at .Norton Mills is not less 

 than 1250 feet. 



In regard to the highest marine shore-line along the north 

 side of the JNotre Dame Mountains, which has been traced 

 from the Gulf of St. Lawrence as far west as South Somerset, 

 Quebec, the question arises whether it is likely to continue 

 further to the west at or near the height reached where we left 

 it and merge into the Iroquois beach ? The last mentioned 

 beach has been traced along the south side of Lake Ontario by 

 G. K. Gilbert from Lewiston, E". Y., where it is 385 feet high, 

 eastward to Watertown, N. Y., where the height is 730 feet. 

 Thence it was followed by J. W. Spencer, who contends that 

 it is of marine origin, to Fine, where the height attained is 



* Report of Progress, Geol. Survey Can., 1863-66, p. 87. 



