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CHAPTHR: LX. 
GLACIAL PHENOMENA AND SUPERFICIAL DEPOSITS. 
GLACIATION AND SUPERFICIAL Deposits, LAKE oF THE Woops—The lake-basin— 
Depth of the lake—Direction of glacial striation—Superposed striation in 
‘different directions—Special instances of glaciation—Pre-glacial age of outfall 
of lake—Distribution of boulders—Upper Silurian limestone boulders with 
fossils—N. E. limit of limestone drift—Methods of accounting for limestone 
drift—DRirr PLATEAU OF EASTERN MANITOBA AND NORTHERN MINNESOTA— 
Kames and Eskers—N. W. limit of red drift—Height and contour of the 
plateau—Sections on Roseau River—GENERAL FEATURES OF GLACIAL PHE- 
NOMENA E. oF Rep RiIvER—Elevation and slope of the Laurentian axis— 
Confluent glacier covering the Laurentian region—Former southern outfall of 
Lake of the Woods—Drirr DeEposirs OF THE SECOND PRAIRIE PLATEAU, 
AND TuRTLE Mountain — Surface of the plateau — Terraces of Pembina 
Escarpment—Sections on Long River —Numerical analysis of constituents of 
the drift—Turtle Mountain—Boulder covered region—MARGIN AND EASTERN 
REGION oF THE T'HIRD PLATEAU—The Missouri Coteau—Ancient river valleys 
—Erratics of the Coteau—Quartzite drift. 
Glacial Phenomena and Superficial Deposits, Lake of the Woods. 
465. The general form of the lake has already been noticed 
(§ 37). It consists of two chief parts—Clear-water Lake to the north, 
and Sand-hill Lake to the south. The basin of the former may be said 
to be excavated entirely in rocks of so-called Huronian age. Sandy or 
gravelly beaches are exceptional, and, as a rule, the rock dips rapidly 
below the surface of the water, and shows wherever exposed, the rounded 
forms due to ice action. This northern part of the lake is also deep, and 
with regard to its form and extent, it may be considered to have remained 
exactly as it now is, since the glacial period. The southern and larger 
part of the lake, properly called Sand-hill Lake, washes bare Laurentian 
rocks along its northern edge, while the whole of its southern and south- 
western margin, is formed of sand and detrital matter, and sweeps round 
in large gently rounded bays, very different from the narrow, irregular 
passages of the north. This southern part of the lake is also compara- 
tively shallow, and perpetually extending its border southward and 
westward, among the swamps, sand-hills and lagoons by which it is there 
surrounded, and spreading detritus thus obtained over its bed. The 
evidence of this is everywhere apparent along its southern margin, 
where tamarack swamps are in some places being so rapidly encroached 

