1904] WELD: BOTANICAL SURVEY OF HURON VALLEY 47 
West of the fence, however, the peat is over 20 (6™) thick, 
and here was a deep part of the lake. Ina few of these borings 
an attempt was made to determine the thickness of the blue 
clay, but there is no sharp separation between the clay and the 
gravel beneath. Figure 6 shows a cross section of the basin in 
an east and west line through the north end of the lake. The 
western slope was not so steep at this place and the lake was 
more disk-shaped. How much deeper than 20" the peat may 
be in places near the lake has not been ascertained. 
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IG. 5.—Section across lake basin from E. to W., halfway between lake and road, 
in line with fence. Hor. scale 1:2160; vert. scale 1 : 360. 
Directly south of the lake is a shallow valley leading over to 
the second lake. A boring in the bottom of this at the fence 
Shows 8*(2.4™) of gravelly clay mixed with dark organic 
materials. This valley was once quite deep and formed a con- 
nection between the lakes, but being narrow was filled up by 
erosion rather than by vegetable deposits. West of this valley 
is a hill now under cultivation, and to the west of this is a broad 
valley in which runs the present outlet of both lakes. The peat 
in this valley is over 16* (5™) deep, showing that here poke a 
broad and deep connection with the second lake, the hill being 
at that time an island. : 
The Three Sisters were then originally two lakes, the third, 
