192 -ZV^e American GeoUxjht. March, 1897 
some time protected from the action of tlie weatlier. On Baf- 
fin land, where the question of pogt-glacial elevation was 
studied,* it was found that tiiere was a marked difference in 
the amount of weathering above and below the zone of former 
water covering. It is, therefore, probable that the freshness 
of the striae near the sea level at Turnavik is only partly due 
to the recency of the ice retreat. 
Although the hills of Turnavik are well rounded, and show 
signs of decided ice scouring (Fig. 2, PI. X), it is evident 
that the glaciation did not succeed in destroying even the de- 
tails of the pre-glacial topography. Evidence of this is par- 
ticularly strong in the dike valleys. These, even though ex- 
tending at an angle to the direction of ice motitm, are pro- 
nounced features of the i)resent topography (Fig. 2, PI. X). 
The pre-glacial decay along the line of these dikes was deeper 
than that on the enclosing gneisses, and the action of the ice 
scouring has not been sutticient to lower the gneisses to the 
level of this decay. Hence in various directions the island 
is crossed by dike chasms, which are deep and narrow, as well 
as remarkably continuous. In some cases at least the disinte- 
grated material has all been removed, and the fresh diabase 
rock exposed in the bottom of the chasm. In other cases there 
is a la37er of till, peat, or foreign rock in the bottom of the 
chasm; and hence in these places it is impossible to deter- 
mine by surface indications whether all the decayed diabase 
has been carried away. This evidence of slight scouring is 
in harmony with that found in BatHn land and Greenland, 
and also in parts of New England. | It shows that pre-glacial 
decay was deep, and that the general ice scouring did not 
lower the surface far below the zone of decay in the weaker 
members of the rock series. 
Northemi Labrador. Near the northern end of Labrador the 
first doubt concerning the presence of ice action arises when 
the Kig-La-Pait mountain coraes in view: and northward to 
Ogua-Lik and cape Mugford, and even as far north as the 
Four Bears (from Lat. 57° to 60") the same doubt arises 
*See Watson, Journ. Geol., v, 1897, 17. 
tSee Shaler on the Geology of Cape Ann, Ninth Annual Report U. S. 
Geol. Survey. PI. LXII. Prof. Shaler interprets this as the result of 
sea action, but my studies lead me to the conclusion that the dike val- 
leys are preglaeial. 
