Benthonic Algae — Scagel 
509 
ince with an average width of about 100 mi., 
constitute the mainland coast. Although not as 
rugged as elsewhere in the Cordillera, the west- 
ern side of the Coast Mts. rises from the sea 
precipitously to summits in places exceeding 
8,000 or 9,000 ft. Several rivers, which rise in 
the plateau country to the eastward, flow com- 
pletely across this range to the Pacific, where 
the lower parts of their valleys, as well as those 
of many streams originating in the mountains 
themselves, continue in the extensive system of 
fjords along the mainland of British Columbia 
(Fig. 1). These sediment-filled systems of valleys 
with steep slopes and numerous deltas can be 
traced in some places even through the coastal 
archipelago, which represents a partly sub- 
merged margin of the Coast Mountains. West 
of the Coast Mountains, and in a partly sub- 
merged condition, lies another chain, the In- 
sular Mountains, of which Vancouver I. and 
the Queen Charlotte Islands are projecting 
ranges. This outer chain stands on the edge of 
the continental platform with the great depths 
of the Pacific seaward from it. Between these 
MONTHS 
Fig. 18. Monthly temperatures of seawater at Pine Island for the period 1942-52. 
