GLACIATION IN THE ATLIN DISTRICT 183 
Regional glaciation.— As evidence of the regional or Cor- 
dilleran glaciation may be taken the occurrence of foreign rounded 
bowlders or erratics upon the upper slopes of the more or less 
isolated mountains of this district. 
A light colored feldspathic granite and jasper are occasion- 
ally found at heights of over 4,000 feet above sea level, and 
2,000 feet above the lower main valleys. 
Mount Minto rises steeply from Atlin lake to a height of 
4,700 feet above it, and 4,000 feet above the surrounding flats. 
The base of this mountain is hornblende-biotite granite, the 
upper portion of it is hornblende porphyrite ; resting upon this 
porphyrite, near the peak, are rounded bowlders of a light 
colored granite and jasper pebbles. 
East of Teslin Lake, on the mountains above Ptarmigan 
Flats, there is a glaciated rock surface ata height of 5,490 
feet above sea level, and about 3,000 feet above the floor of 
Teslin Valley, which is also glaciated. 
Near this place there are bowlders of a peculiar granite, hav- 
ing large crystals of hornblende. Such granite was only seen 
in place in the high, massive range six miles to the south and 
westward, across the deep intervening valley of Hurricane River, 
over 2,000 feet below these opposite ranges. If this valley ex- 
isted at the time of bowlder transportation, it appears to have 
had little directive power. 
Local glactation.— The local glaciation appears to have origi- 
nated from the water shed between Atlin and Teslin lakes. This 
is a district of wide, upland valleys and arctic moors, for the 
most part above timber line. 
Such local glaciers did not cap the mountain groups appar- 
ently, but filled in. the depressions between them, acting as 
carriers and pulverizers of the local rocks only. 
This glacial occupation seems to have been confined to these 
elevated flats and slopes, and the valleys leading down from 
them, in much the same way as with the present coast glaciers. 
At the present time these elevated valleys, which are sometimes 
over a mile wide, are largely covered with more or less assorted 
