GLACIAL SUCCESSION IN CENTRAL LUNENBURG—PREST. 167 
of northern, origin. This shows that the ice sheet did not recede 
far enough to gather before it in its second advance any northern 
drift, while the slight oxidizing of the lower beds reveals a 
length of time which is very limited when compared with that 
of the first great interglacial epoch. This epoch is often repre- 
sented by a slight denudation of the oxidized part of the under- 
lying boulder clay. 
Third Glacial Epoch. 
This, the last invasion of this district by the ice sheet, has 
left as its legacy the local auriferous drift of Blockhouse and 
Dorey’s Brook. In both these places it was probably gathered 
from exposed hummocks and loose debris in the immediate 
neighbourhood. It consists largely of angular slate boulders 
and oxidized clay and gravel, with here and there a few boulders 
eroded from the lower till. The most noteworthy point in this 
deposit, aside from the fact that it contains the gold-bearing dritt 
of Blockhouse, is that the direction of its movement is different 
from that of the lower boulder clay. While the course of the 
latter has been about S. 22° E, that of the former has been from 
8. 50° to 55° E. Thus, while the underlying drift has been 
subject to continental or at least provincial influences, the upper 
drift is local both in composition and course of movement. At 
Dorey’s Brook, also, the course travelled by the upper drift is 
influenced by the local surface contour. Its course is about 
8. 65° E., while that of the quartz in the interglacial clays 1s 
N. 80° to 90° E., and the underlying boulder clay probably 
8. 40° EK. The tracing of the course travelled by the different 
layers of drift, is often a painstaking and difficult study, where 
no striations are left as a guide. But once its origin and the 
course it has travelled are known, it becomes our most reliable 
guide in the search for gold-bearing veins, and as such will 
repay the most patient investigation. 
Post Glacial Epoch. 
The deposits of this epoch consist of modified drift and river 
terraces. At this time the land appears to have been more 
elevated than at present, during which the beds of many of our 
