422 Proceedings. 
advancing beyond the eastern boundaries of the ranges now bordering the 
Canterbury plains proper. Of these gigantic ice streams, the glacier advancing 
through the then united valleys of the Southern Ashburton and Northern 
Hinds was, if not the largest, at least equal in size to the Rakaia glacier, 
owing to the fact that it received enormous additions from the valley of the 
Rakaia (by the lake Heron) and from that of the Rangitata (by the lakes 
Tripp and Acland depressions).* It will thus at once become manifest that 
Captain Hutton's argument (p. 387) concerning the small size of the present 
Ashburton and Hinds rivers falls to the ground, and that he was not sufficiently 
acquainted with all the facts given in that report of mine. 
We thus have north of Timaru four distinct fans, namely, those of the 
Waimakariri, Rakaia, Ashburton, and Rangitata, with smaller rivers having 
their sources in the front ranges running between them ; the Selwyn between 
the Waimakariri and Rakaia fans, the Northern Ashburton between those of 
the Rakaia and of the Ashburton—Northern Hinds ; and the Southern Hinds 
between the latter and the Rangitata fans. The gravel formation of these 
fans, where they remained undisturbed, does not warp, as Captain Hutton 
assumes, round the spurs of the hills at the same level that it has at the river 
gorges, but has a steady fall towards the small streams flowing between the 
fans of the two large glacier torrents; however, in some instances, this has 
been concealed by detritus from the mountains, or by re-arrangement of the 
original river beds on the surface of the upper portion of the plains when the 
glaciers retreated. But, I may add, the general outlines are nevertheless clear 
and distinct. 
In my geological notes on the Malvern Hillst I have given an illustration 
of this. I have shown how the great Rakaia glacier, having also añ outlet by 
the upper course of the river Selwyn, covered with its gravel deposits the 
lower eminences forming the Malvern Hills, west of the dolerite range, and had 
its outlet in a N.E. direction in the neighbourhood of Little Racecourse Hill, 
thus throwing, doubtless, the bed of the Waimakariri more to the north. 
When this glacier outlet ceased to flow and to deposit any more boulders and 
gravel in the district alluded to, the Waimakariri soon began to remove the 
alluvial beds thus formed by the Rakaia branch, until harder rocks upon which 
they were reposing were reached. This fact alone, I trust, will prove that a 
detailed examination of all, physical features in that portion of the country is 
requisite to enable us to understand the sometimes complicated nature of the 
fluviatile beds, and that my explanation of the formation of the Canterbury 
plains is not a mere hypothesis, but based upon a great number of observations 
made during a number of years. 
* See “ Report on the Formation of the Canterbury Plains,” by Dr. Haast, р. 9, et seq. 
Rep. Geol Expl, 1871-72, pp. 33—36. 
