May 12, 1915 
Canada 
Geological Survey 
Museum Bulletin No. 14. 
GEOLOGICAL SERIES, No. 25. 
The Occurrence of Glacial Drift on the Magdalen Islands. 
By J. W. Goldthwait. 
INTRODUCTION. 
The Magdalen islands lie nearly in the centre of the Gulf of 
St. Lawrence, about 50 miles northwest of Cape Breton and 
northeast of Prince Edward Island. They consist of thirteen 
small islands, spaced well apart along a northeast-southwest 
line and tied together by a double line of sand bars (Figure 1). 
The deeply drowned valley which forms the seaward continuation 
of the St. Lawrence estuary passes straight by the northern end 
of the Magdalens, in its course from Gaspe to Cabot strait. 
The islands thus lie near the northern edge of the vast submerged 
plain which occupies the southern embayment of the Gulf of 
St. Lawrence and whose shoreline, a semicircle of about 100 
miles radius, extends from Cape North to Cape Gaspe. The 
water which covers this plain is nowhere very deep, rarely ex- 
ceeding 50 fathoms, and having an average depth of 30 or 40 
fathoms. The major features of the plain are clearly of subaerial 
origin. Broad valleys which increase in depth from 30 to 90 
fathoms cross the plain at its northwest and northeast corners, 
one draining Chaleur bay and the other passing close along the 
northwest coast of Cape Breton island to Cabot strait (See 
map). 
Like Prince Edward Island, the Magdalens seem to be sum- 
mits of upland districts which in Tertiary time overlooked the 
