Il6 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



fragments without the usual filling of fine materials. The size of the blocks 

 themselves is not so remarkable, knowing what a transporting agent a glacier 

 is, as the average size of the fragments making up the moraines. In the case of 

 four of the five glaciers studied, two of these moraines were found and only two. 

 The absence of them in the case of the Yojio is readily understood when the 

 lack of high cliffs is noted. Not one of the glaciers at the present time could 

 form such a moraine, no matter how prolonged the halt. The blocks are angular 

 and show no more glaciation than they might have received upon one face while 

 they were in their original position in the cliff. The blocks were carried upon 

 the ice and were not pushed or dragged along in front of, or beneath it. The fine 

 material was not removed by the action of running water, as might have been 

 done in other cases; but was absent from the first. If we are to account for these 

 moraines we must load the glaciers with a mass ot exceptionally coarse blocks 

 and only a minimum of fine debris. This cannot be done by assuming two periods 

 of excessive weathering for they would produce as much fine material as coarse, 

 and very probably a great deal more. The prevalence of the phenomenon pre- 

 vents our resorting to the ordinary rock slide for our explanation. In the case 

 of the Victoria it built a moraine of the ordinary type, then the two bear-den 

 moraines, and then the present modern moraine essentially like the first. The 

 Asulkan built its outer coarse moraine, then one of the ordinary type, then its 

 younger coarse moraine and subsequently a series of the common variety. An 

 examination of the various cliffs, in connection with each of the four glaciers, 

 from which the material was most certainly derived shows that they all have 

 a trend from north-northwest to west-northwest. A further suggestive fact 

 is that in all cases the bulk of the material fell to the eastward. 



During the season of 1904 no plausible explanation occurred to the writer, 

 but upon leaving the field the idea of a double seismic disturbance came up and 

 was carried back to the mountains in 1905 . It seems now to be the only explana- 

 tion by which to account for the phenomenon. Slipping may have occurred 

 along some of the numerous fault planes traversing the eastern Rockies in a 

 north-northwest direction and the region crossed by westerly moving seismic 

 waves. From cliffs having a general northwest-southeast trend, blocks, already 

 much weathered, would be detached and thrown eastward, comparatively few 

 falling from the westerly facing cliffs. Glaciers most favorably situated for 

 acquiring a load by this means, as the Wenkchemna, have the most massive 

 deposits of the nature described; those unfavorably related to high cliffs, as the 

 Yoho, appear to have made none. The great blocks detached by the earth 

 jars fell into soft neVe", or upon the yielding ice, and were not ground into small 

 fragments as they usually are when they descend to the valley floors. The 

 protection afforded the ice by the material brought about a halt of the front, 

 until the blocks were deposited, when the general retreat was resumed. 



It was reasoned that if the disturbances assumed reached from the Great Divide 

 to the Selkirks, then many other glaciers, equally favorably situated for acquiring 

 a load by this means, should show the same type of moraine, if they were not 



