Landforms of British Columbia 1976 - Department of Geography

trolled by a branch fault, extends from Beresford Inlet to Tahmkwan island, a
distance of 20 miles.
On southern Vancouver Island there are a number of prominent lineaments.
Two outstanding ones have an almost east-west trend. One, the Lee& River
lineament (17) (see photo B.C. 1533:14), extends from the west coast at the
mouth of Loss Creek for 35 miles to the mouth of Goldstream Creek. It follows
the valleys of Loss Creek, Wye Creek, Bear Creek, Leech River, Old Wolf Creek,
and Goldstream Creek, all of which are along the trace of the Leech River fault.
The San Juan lineament (18) extends from Port Renfrew in an easterly direction
for about 35 miles to the west arm of Shawnigan Lake. It follows the valleys of
San Juan River, Clapp Creek, and Koksilah River, which are eroded along the
trace of the San Juan fault.
The Cowichan Valley, occupied by Cowichan River and Lake and by Nitinat
River tributaries, is a curving fault-controlled lineament (19) with a northwesterly
trend and a length of 40 miles. It is only one of a number of fault-controlled
valleys with that general trend.
Liieaments are extremely well displayed in maps and aerial photographs of
the He&e (see Plate VIA) and Georgia Lowlands and of the fiord section of the
Kitimat and Pacific Ranges, by the alignment of river valleys, waterways, lakes,
ridges, and various warps or depressions.
Of the great many lineaments displayed along the coastline, the Owikeno
lineament (20) deserves mention. It is well shown on N.T.S. Sheet 92~ and in
Plate XLVIII by the easterly trending alignment of Elizabeth Lake, Hardy Inlet,
Owikeno Lake, and Machmell River for a length of more than 50 miles. The
photograph shows major joints parallel to the Owikeno lineament crossing a
northerly trending line&on which is the topographic expression of bedding in a
roof pendant.
Grenville Channel lineament (21), 65 miles long, is the longest of the north-
westerly trending lineaments on the coast. There are northeasterly trending line-
aments such as that of Portland Inlet and Observatory Inlet, 60 miles long, as
well as northerly ones such as those of Douglas Channel, Laredo Inlet, and Fitz-
hugh Sound.
Peacock’s study of the fiords of the British Columbia coast indicates that they
are structurally controlled by “axes of folds, the strikes and contacts of geological
formations, and the directions of joints, goes, faults, dikes, mineral veins, and shear
zones of the surrounding country.“*
“Severe folding has affected the pre-batholithic rocks [whose] prin-
cipal fold-axes trend in general northwestward with considerable local sinuosity in
sympathy with the composite crescentic plan of the coastland. This trend is the
same as that of the longitudinal (concentric) component of the concordant pattern
[see p, 1151. A study of the available reconnaissance geological maps of
the coastland reveals many fiord features strictly following the strike of the local
formations and the linear contacts between different formations. Grenville Chan-
nel, an unusually straight and narrow passage (lat. 53” 30’), marks a boundary
between granitoid and slaty rocks along 30 miles of its typical longitudinal
COU*Se.“*
“ All four principal fiord trends are represented by fracture lines; the
longitudinal [northwesterly] and transverse [northeasterly] components of the
concordant pattern are most strongly repreSented; the meridional [northerly]
component of the discordant pattern is less commonly repeated; the east-west
* Peacock, M.i\.. Gd. sot., Am., Bull. “Ol. 46, 193% pp. 656. 657, 658, 660.
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