GROUND ICE. 217 



eleven feet, so that the ground ice was only six feet 

 thick, 



At York Factory, on Hudson's Bay, in lat. 57°, in Oc- 

 tober, 1835, recent frosts had penetrated eight inches 

 into the soil ; the thaw due to the summer heat extended 

 twenty-eight inches beyond this, beneath which a frozen 

 bed seventeen and a half feet thick reposed on thawed 

 mud which had a temperature of 33° F. The mean 

 annual heat of this place is 25^ F., being equal to that of 

 Fort Simpson, which lies five degrees further north. 



At Severn outpost, exactly one degree of latitude to the 

 South of York Factory, and on the same coast of Hudson's 

 Bay, the surface had thawed at the close of the summer 

 of 1835 nearly to the depth of six feet, and the frozen 

 substratum was dug into seven and a quarter feet, being 

 thirteen feet in all, but not passed through, so that its 

 thickness was not ascertained. 



I have no information respecting the ground ice of the 

 Peace River or Saskatchewan prairie districts. 



At Rupert's House, on James's Bay, near the level of 

 the sea, in lat. 51° 26' N., long. 78° 40' W., the soil in an 

 exposed situation in the month of April was frozen to the 

 depth of seven feet ; but under a snow-drift the frost had 

 penetrated only thirteen inches into the earth. At East 

 Main, situated on the opposite side of the same bay, in lat. 

 52° 15' N., long. 78° 40' W., the ground under a snow- 

 drift eight feet thick was frozen to the depth of only ten 

 inches. The pits at these places were not dug deep 

 enough to give any information respecting the existence 

 of a permanently frozen substratum. 



On Michiskum Lake, which lies in lat. 49° N., long. 78° 

 W., on the north side of the watershed that divides the Abi- 

 tibbe, or eastern branch of Moose River, from Lake Temis- 

 caming and the Ottawa, and which is about 700 feet 



