Mesozoic and Ccenozoic Geology and Palfeontology. 311 



envelope detached particles of sand, small pebbles and aggregations of 

 particles of sand. Above the fine stratified clay, yellow clay and un- 

 stratified sand occur. 



Bowlders are found on the Qu'Appelle and its affluents, below the 

 Moose "Woods, and north of the Asslniboine, measuring from 10 to 25 

 feet or more in diameter. 



In Lake Winnipeg, ice every j^ear brings vast bowlders and frag- 

 ments of rock of the Laurentian series, which occupj' its eastern shores, 

 and distributes them in the shallows and on the beaches of the 

 western side. Iq Lake Manitobah, long lines of bowlders are accumu- 

 lating in shallows and forming extensive reefs; the same operation is 

 going on in all the lakes of this region, and is instrumental in 

 diminishing the area of the lake in one direction, which is probablv 

 compensated b}- a wearing awa}' of the coast in other places. 



A remarkable beach and terrace, showing an ancient coast line be- 

 tween Lake Superior and Lake Winnipeg, separates Great Dog from 

 Little Dog lake on the Kaministiquia canoe route. The Great Dog 

 portage, 55 miles from Lake Superior by the canoe route, rises 490 

 feet above the level of the Little Dog lake, and the greatest elevation 

 of the ridge can not be less than 500 feet above it. The difl^erence be- 

 tween the level of Little and Great Dog lakes, is 347.81 feet, and the 

 length of the portage between, one mile and 53 chains. 



The base of the Great Dog mountain consists of a gnelssold rock, 

 supporting numerous bowlders and fragments of the same material. 

 A level plateau of clay then occurs for about a quarter of a mile, at an 

 altitude of 283 feet above Little Dog lake, from which arises, at a very 

 acute angle, an immense bank or ridge of stratified sand, holding 

 small water-worn pebbles. The bank of sand continues to the sum- 

 mit of the portage, or 185 feet above the cla^' plateau. East of the 

 portage path the summit is 500 feet above Little Dog lake. 



Here we have a terrace 500 feet above Little Dog lake, or 863 feet 

 above Lake Superior, or 1,463 feet above the sea. Another beach or 

 terrace occurs at Prairie portage, 104 miles by the canoe route from 

 Lake Superior, 190 feet above Cold Water lake, or 900 feet above Lake 

 Superior, or over 1,500 feet above the sea. 



In the valle}- of Lake Winnipeg, the first prominent beach or terrace 

 is the Big ridge. Commencing east of Red river, a tew miles froiii the 

 lake, it pursues a southwesterl}' course until it approaches Red river, 

 within four miles of the Middle settlements, here it is 67^ feet above 

 the prairie; on the opposite side of the river, a beach on Stonj^ mouu- 



