38 H. F. Rekl — Studies of Midr Glacier. 



time of Vancouver's visit the ice extended below Willoughb}^ 

 island and had a front 300 feet high, it would have to be about 

 2,000 feet high on mount Wright to give a surface slope of 50' ; 

 and a slope of 1°, which is certainly not excessive^ would corre- 

 spond to a height of about 2,500 feet on mount Wright. 



Another point is worthy of notice. From the divide between 

 Tree mountain and Granite canyon the ice is flowing in both 

 directions and is receiving no supply. The surface of the ice 

 here is now about 1,250 feet high. If we suppose the surface 

 melting at the rate of 2 inches a day (the rate observed near the 

 glacier's mouth) for 90 days in the year, and if we entirely neglect 

 the loss due to the flow of the ice, we find that it must sink about 

 15 feet a year. At this rate it would have been at its hightest, 

 some 800 or 1,000 feet above its present surface, between 50 and 

 70 years ago ; and if we also consider the loss due to flow, the 

 greatest height must have been reached still more recentl3^ This 

 rate of loss could not have continued for a longer period or the 

 glacier would now be lower than it is. It follows that from 50 

 to 70 years ago, or less, the rate of loss of ice in the region near 

 Tree mountain was diminished b}^ a supply which was undoubt- 

 edly derived from Main valley. This conclusion is supported by 

 the moraines in main valley. They could not have retained 

 their present course, flowing iij two directions, for a long period 

 Avithout becoming very attenuated. Taking these facts into con- 

 sideration, it does not seem unreasonable to believe that the 

 greatest extent of the glacier was reached 150 or 200 years ago. 



Evidence that the last Advance was of Short Duration. 



I have already mentioned the stratified deposits on the shores 

 of Muir inlet over which the ice now rides. We find a similar 

 state of things at the eastern end of Dying glacier, where the ice 

 rests on earlier deposits. In a gully on the northeastern side 

 of Tree mountain the ice detached from the main glacier is rest- 

 ing on debris. Although sand and gravel form a j^retty solid 

 l)ed, it is hardly possible that they should have resisted the 

 grinding action of the glacier for many centuries, especially when 

 the ice was -much thicker than it is now. Mr Gushing has called 

 my attention to the fact that a gully on the eastern side of H 

 and others on G do not correspond in direction to the glacial 

 scratches, and therefore could not have been excavated by the 

 glacier. Many geologists would consider this a proof of the in- 

 ability of the glacier to accomplish much erosion ; otherwise the 



