Landforms of British Columbia 1976 - Department of Geography

occupy canyons eroded to a considerable depth. “ It is quite possible, therefore,
that volcanic activity may have been initiated either early in Glacial time or prior to
the onset of glaciation. The evidence at hand seems to indicate that the volcano was
active up to some time within the last few hundred years; and it may still be merely
dormant rather than extinct.“*
Near Atlin olivine basalt and related pyroclastic rocks form the cone of Ruby
Mountain west of Ruby Creek, and some lava has flowed down the creek almost to
Surprise Lake. This lava, partly post-Pleistocene in age, consists of thin olivine
basalt flows, each 5 to 15 feet thick and totalling about 120 feet in thickness. The
lava lies above gold-bearing gravels and forms a canyon along the creek. Two fans
of scoriaceous material on the west side of the creek evidently represent the latest
outpouring from the Ruby Mountain cone. On the east side of Ruby Creek there
is one small cinder cone. These occurrences occupy a small area and are the northernmost
evidence of late volcanic activity in British Columbia.
[References: Aitken, J. D., “Atlin Map-area,” Geol. Surv., Canada, Mem.
307, 1959; Black, J. M., “Atlin Area,” B.C. Dept. of Mines, unpublished manu-
script; Kerr, F. A., “ Lower Stikine and Western I,skut River Areas, British Colum-
bia,” Geol. Surv., Canada, Man. 246, 1948; Lord, C. S., “McConnell Creek Map-
area,” Mem. 251, Geol. Surv., Canada, 1948, p, 43; “ Stikine River Area,” Gal.
Surv., Canada, Map 9-1957; Hanson, F. A., “ Reconnaissance between Skeena
River and Stewart,” Geol. Surv., Canada, Sum. Rept., 1923, Pt. A, p. 39; Dol-
mage, v., “Coast and Islands of British Columbia between Burke and Douglas
Channels,” Gal. Surv., Canada, Sum. Rept., 1921, Pt. A, p. 29; Davis, N. F. G.,
“ Clearwater Lake Area,” Geol. Surv., Canada, Sum. Rept., 1929, Pt. A, p. 290;
Mathews, W. H., “ Geology of Mount Garibaldi,” Geol. Sot., Am., Bull. Vol. 69,
1958, pp. 161-198; Mathews, W. H., “Mount Garibaldi, A Pleistocene Volcano,”
Am. Jour.Sci.,Vol. 250, 1952, pp. X1-103; Watson, K. Dep., andMathews, W. H.,
“ The Tuya-Teslin Area,” B.C. Dept. of Mines, Bull. No. 19, 1944; Cotton, C. A.,
“ Volcanoes as Landscape Forms,” Whitcombe and Tombs, Ltd., Christchurch,
1952.1
[Photographs: B.C. 502:6, B.C. 866:34,49; B.C. 984:59, 64; B.C. 985:26;
B.C. 986:90; B.C. 1374:28; B.C. 1744:lO; B.C. 1919:38.]
MAJOR LINEAMENTS OF BRITISH COLUMBIA
Lineaments are extremely common features in the landscape of British Colum-
bia. They are normally on so large a scale, however, that they may be difficult to
recognize on the ground. Many have lengths measured in scores of miles, and
consequently are most frequently discovered through study of topographic maps (see
N.T.S. Sheets 92iv and 103~) or aerial photographs (see Plate XLVIII), or by
direct observation from an aircraft in flight.
A lineament is an alignment of topographic features that is structurally con-
trolled; that is, it is governed by or directly related to some geologic structure. It may
consist of some straight or gently curved topographic feature, such as an alignment of
valleys, wind gaps, scarps, or ridges, whose origin is controlled by faults, joints,
bedding, geologic contacts, foliation, or 1ineation.t Drumlins and glacial flutings
are not lineaments because, although they may be strongly linear in their arrange-
ment, they are not structurally controlled.
Few studies of lineaments in British Columbia have been made, and no pub-
lished results are available. However, their study and investigation is useful. par-
* Kerr, P. A., Ged. surv., Canada, Men. 246, 1948, p. 4%
+ Billings, M. P., “ SfmCtwal Geology.” Prentice HO,,, NW York, 1954, p. 160.
120
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