Pleistocene of ike Winnijjeg Basin. — Tyrrell. 25 
ine is also well seen at Point Brabant and other places along 
the east side of the lake. When the water stood at this level lakes 
Manitoba and Winnipegosis were joined across the Meadow port- 
age, and the beach is therefore to be looked for around the former 
lake. It is probably represented b}' the ridge in the grove behind 
Manitoba House, though the exact hight of this ridge was not 
determined. On the line of the tramwa}- at the Grand rapids on 
the Saskatchewan river four well defined ridges of rounded gi-avel 
occur at the hight of 140, 95, 90 and 80 feet above lake "Winni- 
peg or 850, 805, 800 and 790 feet above the sea. 
At Ox Head, near the northeastern extremity of Black island, an 
ancient beach is ver}- conspicuous at about fort}' feet alcove the water. 
On the south side of the island the beach is marked by a line of 
sand dunes, and on the north side a sandy terrace rises genth* to 
a hight of fort}- feet and ends abruptly at the foot of a steep slope 
thickl}- strewn with lioulders. On ascending this slope the land 
is found to rise to a hight of 100 feet above the lake and its sum- 
mit to consist of an ii'regular aggregation of knolls thickly strewn 
with large boulders of gneiss, very few or none being derived from 
the immediatel}' adjoining and underlying Keewatiu schists. This 
ridge is the summit of the Black' island moraine which would seem 
to have been di'opped here when the higher parts of the island 
were above the surface of lake Agassiz, as there is no sign of water 
action on the moraine above the line of the forty-foot beach. It 
is possible that the moraine may have been deposited aljout the 
water level, and that the water afterwards rapidly receded to a 
height of fort}- feet above the^present lake. 
Delta deposits occur at the mouths of all the wide valle3'S open- 
ing into the west side of the lacustral plain, but unlike the delta 
of the Assinilioine they nowhere extend eastward beyond the 
general line of trend of the escarpment. 
AlluvluTin. 
The Red River valle}' south of north latitude 50^^ is thickly 
covered with alluvium, evidently thicker near the river than far- 
ther away from it, its thickness at Rosenfield being 125 feet, 
while at Morden, t\vent3'-four miles farther west, and just at the 
foot of the Pembina escarpment its thickness is onl}- 15 feet. 
North of latitude 50*^ a soft blue alluvial cla}' overlies the 
Archaean rocks along the whole of the east shore of lake Winni- 
peg beyond Winnipeg river, ranging in depth from 5 to 80 feet. 
