308 Transactions.—G cology. 
_ Lake Guyon is being gradually filled with alluvium, carried into it by the 
streams which flow from the mountains on each side, and, indeed, it is already 
nearly divided into two separate sheets of water by a peninsula many acres in 
extent, which has been formed on its northern side by two of the largest of 
these streams. The amount of solid matter carried into it during heavy rains 
is enormous, and the cireumstance that it has not already been filled is one of 
extreme interest, when considered in connection with the rapid accumulation 
of alluvium in the valley of the Dillon. 
On the lower slopes of the mountain, immediately above the col, are 
innumerable roches moutonnées, many of them of great extent, beautifully 
rounded in general outline, but nowhere presenting the least striation. This, 
however, may be attributable partly to the fact that they are composed of the 
same sandstones as the great mass of the blocks deposited on the moraine, and 
partly to the circumstance that they weather with great rapidity under the 
alternate action of frost and heat, the disintegrated material being removed by 
rain. 
The general conclusions which I have arrived at from a consideration of 
the foregoing, and other grounds, are :— 
l. That the land of which the Middle Island is composed began to rise at 
the close of the miocene period, and attained its greatest elevation during 
pliocene times. 
2. That it rose to an elevation of not less than from 4,000 to 5,000 feet 
greater than its present height above sea level. 
3. That during the period of maximum elevation the land had a quasi- 
continental extension, chiefly to the eastward. 
4. That during this period the land assumed its present physical aspect, and 
that as it rose glaciers were formed in the great mountain valleys. 
D. That all the later marine pliocene deposits then formed were formed 
on the outskirts of the continental area, 
6. That the glaciers, of which the evidences are to be found in those parts 
of the Middle Island mountains to the north and south of Mount Cook, owe 
their disappearance to a subsequent depression of the land, which continued 
during pleistocene times, during which a fresh upheaval subsequently took 
place. 
7T. That during this depression all the later marine pliocene beds of the 
Middle Island tract were again submerged. 
8. That the Middle Island presents no evidence whatsoever of any such 
pleistocene glaciation as is mentioned by Dr. Haast. 
T may add that, in addition to its picturesque beauty, the tract of country 
