STRIKE FIORDS 
151 
Archipelago is so direct in its course that a straight line 
190 miles in length could be laid out upon it without 
touching either shore. It heads in the mainland at the 
extreme north and, trending a little east of south, termi¬ 
nates in the Pacific coast. The southern three-fifths, which 
bears the name Chatham Strait, has an average width of 
about seven miles; the northern two-fifths, known as 
Lynn Canal, averages five miles. Our direct observation 
was restricted to the northern part. 
This straightest of all the passages is also deepest. No 
soundings have yet been charted for the southern third, 
but those of the northern part indicate that a continuous 
channel can be traced with 700 feet as its minimum 
depth, and the maximum depth, as already mentioned, is 
2,900 feet. The bounding mountains, so far as we saw 
them, are 4,000 to 5,000 feet high, and the full depth of 
the trough is in the neighborhood of 6,000 feet. At its 
head the trough divides into four parts, which penetrate 
the upland, first as fiords or inlets and then as river val¬ 
leys. These parts diverge from their point of junction 
like the ribs of a fan, their directions ranging from north 
to northwest; and their courses are remarkably straight, 
especially in the lower parts. 
The unusual straightness of this great trough naturally 
suggests that its course was determined by some struc¬ 
tural feature, such as a fault or the outcrop of an easily 
eroded rock. Its breadth is in better accord with the 
second of these tentative explanations; but the matter is 
not free from doubt. If the trough is a strike valley, we 
should naturally expect to find parallel valleys associated 
with it, but the number of such is limited. A short 
parallel trough lies fifteen miles west of Lynn Canal 
and contains Excursion Inlet. East of Chatham Strait 
are Seymour Canal and Stevens Passage, which are 
approximately parallel. But a number of other features 
