180 LIFE OF THE PLEISTOCENE 



ponds occupy the highest points, and contain a varied molluscan fauna. The 

 fresh water and land forms, as well as the typical marine species found in these 

 deposits, are listed below: 



Fresh Water and Land Species Marine Species 



Galba caperata Saxicava arclicd m * 



" umbrosa ( = elodcs) Macoma groenlandica 



Sphaerium species Mya arenaria 



Thuja occidentalis-"* " truncata 



Larix americana Mytilus edulis 



Picea nigra Zostera marina 



Populus grandidentala Algae 

 Menyanthes trifoliala 



The marine species are all shallow water forms, indicating that the deposit 

 is the Saxicava sand. In the clay beneath this deposit Leda portlandica was 

 found, indicating a period of deeper water (the Lada clay). 



C. LAKE ST. JOHN 



Unio shells have been found in a brickyard at Reberval, on Lake St. John. 

 The strata of this region are distributed as follows: 205 



1. Peat and bogs and decomposing vegetable matter. 



2. Lucustrine and fluviatile sands and clays sometimes containing shells of Unio. Except 

 for the presence of these shells it would be difficult to distinguish the sands of this series 

 from the Saxicava sands. 



3. Saxicava sand and Leda clay. 



4. Boulder clay. 



5. Decomposed rock in situ. 



On the west side of Lake St. John, fresh water shells have been observed 

 in clay beds at heights of 25 and 30 feet above the lake, which is 341 feet above 

 sea level. Marine shells have been observed in deposits at Chicoutimi, some 

 distance down the Saguenay River. The lacustrine deposits evidently repre- 

 sent a time later than the Champlain submergence when Lake St. John stood 

 some 40 or 50 feet higher than at present. It is probable that the land had 

 been elevated sufficiently to cause the sea to retreat far enough from this 

 region to hold the accumulating fresh water at this height. In other words, 

 these strata were formed during the waning of the Champlain substage. 



2,1 In Leda clay at Mile End; see Geol. Can., p. 976. 



jwa p or a f u jj ii st f (-kg Marine fossils from this locality, see Stansfield, '15, pp. 65-67. 



2 ° 5 Chalmers, An. Rep. Can. Geol. Surv., XVI, 1904, pp. 2 50-2 63 A, 1906. 



