226 WILLIAM S. COOPEK 



elapsed since the deposition of moraine III, and that the average 

 annual rate of retreat since that event has been less than 6.1 

 feet (1.9 meters) — probably considerably less. If then the 

 Alpine Club record of 14.2 feet (4.35 meters) per year is a true 

 sample of the rate for the whole front, the present rate of re- 

 cession is very far above the average, in which pauses and per- 

 haps slight advances must be reckoned. 



The natural way of approach to the Robson moraines is from 

 the shingle flat. The first and oldest has an abrupt front ten 

 to fifteen feet in height, and is about 300 feet (100 meters) in 

 width. Its surface shows the usual hillocks and kettle holes, 

 and the materials of which it is composed are mostly small and 

 well compacted. Just beyond the first moraine is a silt-filled 

 depression, and next to this the second moraine — a small one, 

 75 to 100 feet (23 to 30 meters) wide, with an abrupt front ten 

 feet in height. A second depression is followed by the third 

 moraine, the most massive of all, in width equal to the first, 

 and with a front slope 40 to 50 feet (12 to 15 meters) high. 

 The fourth is similar in proportions to the third. The ice rests 

 upon the fifth, which is separated from the preceding by a 

 depression in which flows for half the width of the ice front the 

 main outlet stream of the glacier. 



Travelling in reverse direction, from youngest to oldest de- 

 posit, we will now trace the development of the Moraine Suc- 

 cession. The fifth moraine, upon which the ice now rests, is 

 very difficult of access because of the outlet stream, and is prob- 

 ably entirely bare of vegetation. The fourth, viewed from even 

 a short distance, would also appear to be without plants. Care- 

 ful search however over a considerable area — an acre or two — 

 revealed the presence of a few scattered individuals^ — about one 

 hundred in the space examined. Willow seedlings were present, 

 and also Epilobium latifolium L., Castilleja pallida Kunth, 

 Saxifraga aizoides L., Lychnis apetala L., and a single seedling of 

 Picea Engelmanni, thirteen years old. It is worth noting that a 

 spruce cone was found upon the iceward edge of the moraine, 

 close to the outlet stream. The plant population upon the 

 fourth moraine is so sparse and so varied that it is impossible 



