line of weakness. The glacial striae cross over it obliquely, at an 
about 30° with its directiov, and the ice has had wonderfully littl 
on its shape, having succeeded only in rounding off somewhat the es 
angles of the cliffs. Nor has the river had much effect on the rocks, 
they still retain their rounded aspect and show ice  striation almos 
everywhere. “et be. 
473. The distribution of boulders and iguiellod material in the IL 
of the Woods region, is worthy of some attention. The whole southe 
part of Sand-hill Lake is characterized by the abundance of fragments ¢ Of, ae 
limestone, in association with boulders of rocks represented in the nor h . tr 
ern part of this division of the lake, and in Clear-water Lake, ‘Dr. aa 
Bigsby in his paper already referred to¥ gives reasons for believing — ; 
that a deposit of limestone of Upper Silurian Age, overlaps the meta- ; 
morphic series in the southern part of the lake, and though I have - 
been unable to confirm this idea by the discovery of any of the rock se 
in situ, there is considerable evidence tending to show that his suppo- | 
~ 
a 
. . Tee 
position may be correct. At Driftwood Point, five and three quarter Pit 
; i 
miles south of Flag Island, the gravel of the shore is largely composed of 
compact limestone in small fragments. From this place to Reed Riven ; a. 
Bay, many large Laurentian boulders stand on the shallows far outin the — 
Lake, and much of the shore-gravel is of limestone. In the north-eastern — 
angle of the Bay, in many places, about one half d the gravel of the shore — 
appears to be of the same limestone. | 
474. A mile north of Reed River, a dry point projects from the 
general tamarack swamp ofthe shore, and consists almost entirely of 
boulders and gravel. The greater part of the material is Laurentian, the 
boulders being of granite, gneiss, mica-schist, &c., precisely similar to that 
seen to the north, and from the size of pebbles to six and eight feet long. 
Next in numerical importance are the limestone boulders. None of these 
are so large as some of the Laurentian, but this may arise only from the — 
fissile character of the rock, and the manner in which it is affected by 
frost, nearly all being angular and chip-like fragments. The stone is — S 
hard and compact, more or less concretionary in aspect, often cherty, and | 
giving fire under the hammer. Its colour is greyish-drab, to cream-white, 
and yellowish or reddish, on fresh fracture; weathering to pure white. The 
weather also forms small reniform hollows in it, and in many specimens 
gives rise to a minutely pitted structure. From the limestones of this’ 
locality, and fragments of the same rock found west of the Lake of the 
* Also in a paper on the Erratics of Canada, Journ. Geol. Soc., 1851, 
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