SUPERFICIAL GEOLOGY OF BRITISH COLUMBIA. 101 



elevation above the sea is 3240 feet ; and standing on the summit, 

 one commands a very extensive view in all directions. Westward, 

 at a distance of about fifteen miles, across the deep Eraser valley, 

 hills surpassing this in altitude are seen. Southward no part of 

 the surface of the country is so high till beyond the valley of the 

 JBlackwater river, at a distance of over thirty miles. Westward 

 and south-westward, with the exception of one hill of about equal 

 height, the plateau stretches for from fifteen to twenty miles ; 

 while through more than a quadrant of arc to the north, the whole 

 country appears to slope gradually away from the foot of Tsa-whuz, 

 towards the low region about McLeod Lake and the Parsnip river, 

 and forms a level sea-like horizon. No high mountains appear in 

 any bearing. The rocks of the summit of Tsa-whuz are for the 

 most part roughened by the weather ; but in several places indistinct 

 striation is seen ; and in one spot, within a few feet of the highest 

 point, a slightly overhanging surface of basalt was observed to be 

 distinctly shaped and polished by ice, the direction indicated being 

 a few degrees west of south. The surface of the northern ridge 

 of the mountain shows miniature rock-basins, with their longer 

 axes parallel to the same direction, and some of them holding 

 small pools. The ridges which diversify the surface of the plateau 

 below are seen to conform very generally to north-and-south bear- 

 ings ; and this is especially observable immediately to the south of 

 Tsa-whuz, where a succession of small ridges are closely packed 

 together, with their longer axes running S. 25° W. Some of these 

 hillocks probably owe their form to that of the underlying rock, 

 while others are no doubt composed of gravel; and the general form 

 of these and of Tsa-whuz is as though the glaciating agent had moved 

 from north to south. 



Traces of glaciation were also noticed in several places at high 

 levels on the basaltic plateau in the vicinity of the Eraser valley, 

 in positions not allowing their being referred to local action. In two 

 cases very distinct grooving was observed. In one of these localities, 

 about twenty miles north of the Chilcotin river, and several miles 

 distant from the trough of the Fraser, the direction is nearly true 

 north and south, the approximate elevation being 3350 feet. In a 

 second instance, also on the summit of the plateau, on the northern 

 brink of the Chilcotin valley (lat. 52°), at an elevation of about 

 3650 feet, with a direction of S. 23° W., or N. 23° E., being transverse 

 to the present great gorge of the Chilcotin river, the surface of 

 the narrow basaltic plateau forming the summit between the south- 

 western tributaries of the Nechacco and some of the north-western 

 branches of the Blackwater, at an elevation of 3730 feet, is ice- 

 smoothed, but the direction of motion is undeterminable. 



On the summit of a hill which we may call Sinter Knoll, rising 

 about 250 feet above the general level of the country, or 3550 feet 

 above the sea, north of Gatcho Lake, near the south-eastern sources 

 of the Nechacco river, glaciation occurs with a bearing about 

 S. 8° E. The rock of the hill is a remarkably brecciated siliceous 

 material — hard, but much jointed. The striation was only found 



