686 Me. e. j. gakwood on the [Nov. 1899, 



carried with great force along the tunnel during the bursting of the 

 lake in the previous spring, and, when we saw it, still strewed the 

 mouth and floor of the tunnel; the direction of this channel, as 

 previously stated, was at right angles to the main lie of the valley, 

 so that on the valley becoming free from ice, as the climate amelio- 

 rated, this waterworn glacial material would be deposited as a 

 gravelly ridge, running roughly at right angles to the long axis of 

 the valley and forming a kame. (See PI. XLYII, fig. 2.) 



Y. Eate op Movement of the Ice. (PI. XLIV.) 



During our short visit to the interior we were unable to under- 

 take any measurements to ascertain the rate of movement of the 

 ice- sheets. From what we saw of them, however, I am inclined to 

 think that the motion is not nearly so great as that of the glaciers 

 near the coast. The rate of advance of these latter glaciers was not 

 accurately measured ; but, judging from observations made before 

 and after our journey into the interior, I do not think that this 

 rate can average less than 15 or 20 feet in every 24 hours. I have 

 endeavoured to check this estimate by observations made on 

 the size of the icebergs daily calved from the front of King's Bay 

 Glacier. The bergs here do not appear to be produced by any 

 strain on the ice due to a sudden fall in the ground along the edge 

 of the coast, but are caused primarily by the action of the tides. 

 As the tide rises, the upward pressure exerted by the water upon 

 the submerged portion of the glacier-front forces off a narrow 

 strip of ice which breaks up and floats away in the form of 

 icebergs. The same phenomenon takes place daring the fall of the 

 tide, and, as the support of the water is withdrawn, another slice is 

 removed. This discharge appears chiefly to occur immediately after 

 half-tide ; in both cases the amount broken off will therefore 

 represent half the portion of ice which has advanced in the in- 

 terval between one complete rise and fall of the tide. Broadly 

 speaking, then, four periods of discharge may be said to occur every 

 24 hours. I endeavoured to estimate the width of the bergs collected 

 in front of the glacier as we rowed through them on the evening 

 after our return to the coast ; many of these could not have been 

 less than 8 to 10 feet across in their shortest diameter. If, 

 therefore, we suppose these to represent the width of ice broken 

 off during one rise or fall of the tide, this would give 32 to 40 feet 

 as the amount of advance in 24 hours ; or even supposing that these 

 larger bergs represent a portion of the ice-front which resisted one 

 rise or fall of the tide, and which would represent the advance 

 during half a day, it would give 16 to 20 feet for the daily 

 motion of the glacier. In addition, however, to the larger bergs, 

 splinters of ice were constantly falling throughout the day ; and I 

 do not think, therefore, that an estimate of 25 feet for the motion 

 of this glacier during every 24 hours would be excessive. 



