THE SUCCESSION OF DEPOSITS. 59 



found on the Chaudiere lake, 183 feet above lake St. 

 Peters, on the Madawaska 206 feet, and at Fort Coulonge 

 lake 365 feet above the same level, a very interesting 

 indication of the gradual recession of the capelin spawn- 

 ing grounds from this last high elevation to the level of 

 the more celebrated locality of these fossils at Green's 

 creek. Farther, throughout the counties of Kenfrew, 

 Lanark, Carleton and Leeds, the marine deposits rise to an 

 elevation of 425 feet, or nearly the same with one of the 

 terraces on Montreal mountain ; but while this eleva- 

 tion would, with the present levels of the country, carry 

 a deep sea to the head of lake Ontario, no marine fossils 

 appear to have been found on the banks of that lake. 

 Was the depression of the later Pleistocene period limited 

 to the country east of lake Ontario, or have the marine 

 deposits of the upper St. Lawrence hitherto escaped 

 observation or been removed by denuding agencies ? The 

 question awaits further explanations for a satisfactory 

 answer. 



3. The Saxicava Sand, and Upper Boulder Deposit. 



When this deposit rests upon the Leda clay, as is not 

 unfrequently the case, the contact may be of either of two 

 kinds. In some instances the surface of the clay has 

 experienced much denudation, being cut into deep 

 trenches, and the sand rests abruptly upon it. In other 

 cases there is a transition from one deposit to the other, 

 the clay becoming sandy and gradually passing upwards 

 into pure sand or fine gravel. In this last case the lower 

 part of the sand at its junction with the clay is often 

 very rich in fossils, showing that after the deposition of 

 the clay a time of quiescence supervened with favourable 

 conditions for the existence of marine animals, before the 



