304 T'ransactions.— Geology. 
geological science ; and if it be admitted, on Ње one hand, that when the 
period began it found the existing systems of hill and valley in the main 
determined, it must also be admitted, on the other hand, that it cannot have 
left them exactly as it found them. The intensity given to denuding agents 
by frost, or rather by the alternations between frost and thaw, is well known 
io be enormous ; and it is impossible that a glacial period should have come 
on, should have endured for a long period of time, and should have gradually 
given way to a more genial climate, without having left upon the pre-existing 
surface powerful and lasting effects. But the conclusion that the glacial 
epoch deepened within certain limits pre-existing valleys, degraded to a like 
extent pre-existing hills, filled up estuaries with moraine matter, or with sand 
and gravel, or covered a great extent of country with boulder-clay, all this is 
very different from the conclusion that our existing systems of hill and valley, 
and even of sea and coast, have been all cut out of the solid by some great ice 
sheet of enormous thickness, which was quite independent of local glaciers, 
and which did not derive either the cause or the direction of its motion from 
the mountains which we now see." Further on, after referring to the present 
glacial conditions of Greenland and of the great antarctic continent, his Grace 
says :—“ From observations such as these we may be assured, I think, of the 
truth of the theoretical conclusion that lofty mountain chains, with all their 
characteristic variety of surface, must, in allages and in parts of the globe, 
have preceded the development of glacial conditions, and that in these chains 
the unequal elevations.and depressions, which are the work of subterranean 
force, have ever been the guiding and controlling cause of glacial action." 
Moreover, such a glaciation as Dr. Haast suggests in the report above alluded 
to must necessarily have obliterated all but the scantiest fragment of the fauna 
and flora of the country, leaving, indeed, at most but a few alpine forms 
struggling for existence amidst the inhospitable conditions by which they were 
surrounded ; whilst, on the other hand, the study of the existing forms of life, 
and of those which have certainly become extinct within pleistocene times, has 
led all who have engaged in it to a conclusion entirely at variance with any 
such assumption. I propose, however, to deal with this question more fully 
in a future paper. 
I will now proceed to describe, in some detail the glacier phenomena 
presented to us in the upper parts of the valleys of the Buller and the Dillon, 
which I have selected as well marked types of those which are exhibited in 
other parts of the great mountain range of the Middle Island. 
These two rivers, as well as many other of the larger rivers in the northern 
part of the island, have their sources in the great mountain system named by 
me the “Spencer Mountains,” which occupy the centre of the tract of country 
comprising the Provinces of Nelson and Marlborough. The highest point of 
