1907.] NATURAL SCIENCES OF rillLADELPIIIA. 563 



storm. The changes, though not marked, arc all in the line of shrinkage 

 and recession. The tongue, still buried in moraine, is not different from 

 previous years, but the steep slopes of ice on the left side are gradually 

 retreating and depositing masses of bowlders on the ground moraine 

 below. The large angular blocks whicli fell from the ice in 1899 are 

 now 126 feet from the edge of ice, which indicates a further retreat of 

 fifty-two feet since July 30, 1906. The large boulder on the ice surface 

 has moved many feet down with the ice, but owing to the bad weather 

 and dense fog which obscured the line points it was not possible to 

 determine the changes with any accuracy. 



YoHo Glacier. 

 Yorio Valley, Field, British Columbia. 



This glacier was visited on August 19, 1907. It has receded very 

 appreciably the past j^ear, particularly on the left side, where many 

 acres of roches moutonne have been left bare or covered with masses 

 of moraine. Some of these are glaciated and graved most beautifully, 

 and many small spherical quartzite pebbles about the size of marbles 

 and quite as true w^ere found in pockets where they had been deposited. 



The right side of the glacier does not appear to have changed so 

 greatly, probably owing to the form of glacier bed and the increased 

 pressure of ice on this side. 



As with other examples in this region, the point of greatest extension 

 of the glacier is a very long blade-like tongue extending in one of the 

 trough-like grooves parallel with the axis of the glacier. Measuring 

 from the bed rock marked on August 17, 1901, to this ice the distance 

 was found to be 147 feet 4 inches, or a recession of 70 feet for 

 the year. If, however, the line is taken in the same direction as 

 previous years the distance was 423 feet, or 346.3 feet recession. 

 This is the greatest change which has been noted in any glacier in this 

 region since observations were recorded. 



As a conclusion it may be noted that the yearly average flow of the 

 ice streams continues about as in previous years, but the recession of 

 the tongues, shrinkage and breaking dow^n is increasingly marked. The 

 Asulkan Glacier, which for several years was stationary or slightly ad- 

 vancing, has this year showed marked retreat and shrinkage, and the 

 same is the case wdth the Victoria Glacier. Preceded by a cold and 

 stormy winter and a summer with low average of sunshine and low 

 temperature, these conditions point to an interesting series of changes 

 which may ultimately throw some light on the relation between 

 weather conditions and glacier change. 



