592 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



followed in general the 7,800-foot contour, though, of course, the surface rose 

 and fell with the varying conditions of topography and exposure of the neve. 

 The ten-mile strip of country between these mountains seems to have borne 

 a massive, continuous snowfield which shed ice to the westward as well as to 

 the eastward. Between the two mountains, the Ashnola valley at the Forty- 

 ninth Parallel carried a load of about 3,000 feet of ice. Below the 7,800-foot 

 contour the peaks and ridges to the east of Cathedral Peak were covered by 

 the ice. The cap was in part supplied by cirque glaciers which headed among 

 the summit ridges. At Mt. Chopaka, twenty miles to the eastward, the surface 

 of the ice-cap followed the 7,200-foot contour. From that mountain to 

 Cathedral Peak the surface of the ice rose, on the average, some thirty- feet 

 to the mile. 



Above the upper limit of the ice the peaks are greatly disintegrated and 

 wide-spread felsenmeers are usually present. At those levels the granites were 

 sometimes seen to be deeply weathered, with the generation of many boulders 

 of secular decay. Below the ice-limit, the erosive effects of the ice-cap are 

 very striking, often rivalling in intensity those observed on the bed of the 

 Labrador ice-sheet. The efficiency of the ice-cap as an erosive agent in this 

 range is remarkable in view of the fact that the average depth of the ice was 

 little more than 1,000 feet, while we have seen that ice three times as thick 

 was incapable of performing much erosion on the lower mountains across the 

 Similkameen. The difference in erosive power is doubtless to be explained by 

 the steeper surface, bottom gradients, and frequent local concentration in flow 

 of the ice mantling the Okanagan range. 



The strong topography naturally influenced local ice-currents in high 

 degree. It is highly probable that the ice-cap was succeeded by many cirque 

 glaciers, the erosive effects of which are superimposed on those of the older 

 ice-cap. Care was therefore taken to note the striations and furrowings engraved 

 on the higher divides where cirque glaciers could not have flowed. Such read- 

 ings were not numerous but they showed that the average direction of movement 

 for the ice-cap was about S. 30° E. 



About twenty-five cirques or cirque-like gulches occur in the range where 

 crossed by the Boundary belt. These have been sunk in granitic rocks in which 

 the natural joint planes render glacial plucking specially easy. As usual the 

 attack of the cirque glaciers has often left the ridges asymmetric, with the 

 steeper slopes on the east, northeast and north. 



West of Park mountain and. Peeve Pass the great snowfield shed local, 

 often confluent, glaciers southwestward toward the Pasayten valley. Definite 

 proof that the direction of movement was thus different from that on the eastern 

 slope of the Okanagan range, was furnished at several points. One of the most 

 conclusive evidences was found in the fact that the 6,800-foot ridge southwest 

 of the ' Basic Complex ' on the Park mountain divide, is abundantly sprinkled 

 with boulders of the rocks peculiar to the complex. These basic boulders were 

 immediately seen to be erratic as they lay on the gray ledges of the Remmel 

 granite. From this ice divide westward the glaciation was not general; each 

 mountain-block was a local center of accumulation from which great valley 



