100 



GEORGE MERCER DAWSON ON THE 



direction of movement S. 22° E. ; but in every case the motion 

 appears to have been directly down the valley, and to have con- 

 formed to its changes in course. Glacier-ice may still be seen 

 shining bluely from some of the higher valleys at the head of the 

 inlet, and further up the Howathco river there are many glaciers 

 in lateral valleys, some of which descend almost to the river- 

 level. 



Mr. James Richardson, who has had an opportunity of examin- 

 ing many of the inlets north of Yancouver Island, writes as follows* 

 — " Throughout the whole of the inlets and channels which were 

 examined, wherever the surface of the rock is exposed, the ice-, 

 grooving and scratching is very conspicuous, from mere scratches 

 to channels often several feet in width, and from a few inches to 

 as much as two or three feet in depth. Often they can be distinctly 

 seen with the naked eye, from the surface of the water to upwards 

 of 3000 feet above it on the sides of the mountains* They run in 

 more or less parallel lines, and are not always horizontal, but 

 deviate slightly up or down." 



3. Interior oe British Columbia. 



The region lying between the Cascade or Coast Mountains on the 

 west, and the Selkirk or Gold range and Rocky Mountains to the 

 east, though it may be be regarded in a general way as a great 

 plateau sloping gradually to the north, from its broken and diver- 

 sified character offers a problem with many additional elements 

 of complication. The phenomena may be divided as before, under 

 the heads of rock-marking or striation, and overlying detrital de- 

 posits. The striation, however, admits of subdivision into many 

 different systems; and the superficial deposits may be classed as 

 unmodified and modified drift and moraines, between which lines 

 can be drawn in a manner which, though even here not always 

 absolutely definite, could not be attempted with the drift covering 

 the southern part of Yancouver Island. 



a. Striation and Bock-polishing. 



In several cases I have observed grooving at such heights and 

 with such bearings as to preclude the possibility of its being attri- 

 buted to glaciers moving from any of the present mountain-systems, 

 and seeming to require for its explanation ice-action on a very 

 much greater scale. As few localities offer, however, where traces 

 of this character can be observed under quite unequivocal circum- 

 stances, it may be proper, in view of their interest, to treat of the 

 more important in some detail. 



Tsa-whuz Mountain (lat. 53° 40'), on the direct trail from 

 Blackwater Bridge to Port George, is an isolated basaltic outlyer, 

 rising about 800 feet above the higher parts of the surrounding 

 hilly plateau, about midway between the valleys of the Fraser and 

 Chillacco rivers, which lie east and west of it. Its approximate 



* Report of Progress Geol. Survey of Can. 1874-75, p. 8. 



