42 Cincinnati Society of Natural History. 
on the movement of tides and currents. In some instances, as at Cote 
des Neiges, near Montreal, and on the terraces on the Lower St. Law- 
rence, it is obviously merely a shore sand and gravel, like that of the 
modern beach, | 
The terraces and inland sea cliffs have been formed by the same 
recession of the sea which produced the Saxicava sand. At Montreal, 
where the isolated mass of trap, flanked with Lower Silurian beds, 
constituting Mount Royal, forms a great tide-gauge for the recession 
of the Post-pliocene sea, there are four principal sea margins, with 
several others less distinctly marked. The lowest of these, at a level 
of 120 feet above the sea, corresponds, in general, with the level of the 
great plain of Leda clay in this part of Canada. On this terrace, in 
many places, the Saxicava sand forms the surface, and the Leda clay 
and Bowlder clay may be seen beneath it. Another at 220 feet in 
height furnishes Saxicava sand resting on Bowlder clay. Three other 
terraces occur at heights of 386, 440 and 470 feet, and the latter has, 
at one place, above the village of Cote des Neiges, a beach of sand and 
gravel, with Saxicava and other shells. Even on the top of the 
mountain, at a height of about 700 feet, large traveled Laurentian 
bowlders occur. | 
~The prevalent Post-pliocene deposit on Prince Edward Island is a 
Bowlder clay, or in some places bowlder loam, composed of red sand- 
stones. Thisis filled with more or less rounded and striated bowlders 
of red sandstone, derived from the harder beds of the island. At 
Campbellton, however, in the western part of the island, a bed of Bowl- 
der clay is found filled with bowlders of metamorphic rocks, similar to 
those of the mainland of New Brunswick. Strise on the northeastern 
coast of the island have a direction S.W. and N.E. ; and on the south- 
western coast S. 70° E. | 
At Campbellton, in the sand and gravel above the Bowlder clay, 
Tellina greenlandica occurs, at an elevation of about 50 feet above the 
sea. On the surface of the country, there are numerous traveled 
bowlders. Those of granite, syenite, diorite, felsite, porphry, quartzite 
and coarse slates are identical, in mineral character, with those which 
occur in the metamorphic districts of Nova Scotia and New Brunswick, 
at distances from 50 to 200 miles to the south and southwest; though 
some of them may have been derived from Cape Breton on the East. 
Those of gneiss, hornblende schist, anorthosite and labradorite rock 
must have been derived from the Laurentian rocks of Labrador and 
Canada, distant 250 miles or more to the northward. 
