410 Newer Pliocene and Post Pliocene Deposits 



If the land were slowly rising, so as to narrow the basin and 

 limit the supply of sea water, species previously abundant might 

 be diminishing in size and numbers; and in places storms and 

 inundations might shut up shoaling bays, and inclose and destroy 

 marine fishes frequenting such spots, entombing their remains 

 along wiih those of sea weeds and of leaves of land plants drifted 

 or blown from' the shore. During such elevation, also, the posi- 

 tions of beaches, sand banks, and muddy bottoms, would be con- 

 tinually changing, so that similar alternations of argillaceous and 

 coarse beds might be found at very different levels. 



Such I suppose to have been the condition of the latest of the 

 newer Pliocene, or post Pliocene sea areas of this part of the St. 

 Lawrence valley, represented by the littoral sand and gravel of 

 the lowest terrace or plain. 



The clay which underlies this plain is of greater age, and is 

 characterized by one deep sea shell which may represent a depth 

 of from 100 to 300 feet or more, or a shore level of 200 to 400 

 feet above the river. We should, of course, expect to find the lit- 

 toral shells belonging to this sea bottom at a higher level on the 

 mountain, and at a greater distance from the river on the sur- 

 rounding high lands. 



Two of the most strongly marked terraces on the mountain 

 occur at heights of 220 and 386 feet above Lake St. Peter. On 

 these no shells have been found. If they existed, they have per- 

 haps been swept away by land floods, or by the recessibn of the 

 waters. Westward of Montreal, Sir W. E. Logan reports that 

 gravel, sand and littoral shells occur near Kemptville on the 

 Prescott Itoad, at an elevation of 250 feet above Lake St. Peter. 

 Another locality in Winchester is 300 feet high, another in 

 Kenyon 270 feet, and two others in Locheil 264 and 290 feet. 

 Sand and shore shells occur at Hobbes Falls, Fitzroy, at a height of 

 350 feet. At'Dulham Mills on the De L'Isle, according to Mr. 

 Murray, slitells occur at a height of 289 feet above the St. Lawrence. 

 Eastward of Montreal, Mr. Barnard, C. E., informs me that shells 

 occur in gravel, near Upton Station, on the Portland and St. 

 Lawrence railroad, 257 above the St. Lawrence, and in circum- 

 stances indicating shallow water. Still further to the east and 

 north, on the River Gouffre, near Murray Bay, Sir W. M. Logan 

 found two terraces with littoral shells at heights of 130 and 360 

 feet above high water level. The first probably corresponds to 

 * our 100 feet level at Montreal, the latter to one of the higher 

 shores above mentioned. 



