GrREEN — A Journey among the New Zealand Glaciers. 645 



saw, that we may ask, "What is the cause of a feature so distinctive ? 

 I believe the low level to which the glaciers descend, and the con- 

 sequent short incline of the rivers, is a sufficient cause. The terminal 

 face of the Tasman glacier is, according to Dr. Haast, only 2456 feet 

 above the sea; while the mean of four observations, taken in as many 

 days by myself, makes it 100 feet lower ; and its river descends to the 

 sea level by a fairly uniform incline of about 25 feet to the mile. If 

 the river had a greater depth to descend before reaching the level 

 country or sea level, it would erode a deep ravine- shaped bed, like 

 those so common in the European Alps. High up on the mountain 

 slopes, on the side of the valley opposite to where we travelled, were 

 the most remarkable series of terrace formations I ever saw, their 

 level being quite 500 or 600 feet above the present river, and their 

 edges sharply defined. Dr. Haast considers that they form part of the 

 margin of an ancient lake, which was dammed up by a glacier cross- 

 ing the valley lower down during the last great glacier period. 



Accepting, in part, this interpretation of the phenomena, several 

 interesting questions follow, which we shall try to answer : What river 

 or'rivers fed this lake ? Was it the Tasman ? The present source of 

 the Tasman being about 200 feet lower than the terraces, would be 

 below the level of the ancient lake, so that it could not have been 

 the feeder, unless the lake existed in an inter-glacier period, when the 

 climate was milder, the ice-cap smaller than at present, and the source 

 of the Tasman higher up the valley. Supposing it was not filled by 

 the Tasman river, it seems to follow that, at the time of the existence 

 of the lake, the great trunk glacier formed by the junction of the Hooker 

 and Tasman glaciers must have filled up the centre of the valley, and 

 extending far away down beyond the terraces, formed the dam which 

 banked up the drainage of the hills above the terraces, and thus formed 

 a lake similar to the Merjelen-see in Switzerland. At the same time 

 the main drainage of the great glacier passed along at a lower level, 

 and issued from its ice cave miles lower down, as the stream of the 

 great Aletsch does at the present day. 



That the Tasman glacier has been down the present valley at 

 almost its present level, past the foot of the slopes on which the 

 terraces occur, is proved by the existence of several little mounds of 

 old terminal moraine which the river has failed to remove ; and until 

 the structure of these terraces is more closely examined it is quite pos- 

 sible to suppose that they may have been formed by the direct action 

 of the glacier banking up the debris that fell from the mountain sides. 



The heat as we journeyed up the river bed was intense ; dark 

 masses of rain-clouds blocked up the Hooker valley, while the Tasman 

 remained clear, except for a passing shower. Along the course of the 

 river small whirlwinds followed each other at regular intervals, making 

 themselves visible by the cloud of fine sand which they whirled up- 

 wards to a height of from 50 to 100 feet. 



At three p.m., on February 12th, we commenced to ford the 

 Tasman, and at 6 '30 we reached its further shore. Halting for the 



