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of nearly 200 feet below it, from a few miles within the coast line 
to the foot of the hills, is altogether composed of hard grey shingle 
and gravel filled up with variable proportions of sand and fine sili- 
cious silt. It is usually quite permeable to water; but nearer the 
sea , where the finer mud has been deposited in lagoons , deep beeds 
of impermeable soil are found. Nowhere over the whole extent 
of the plains has a trace of marine deposit been discovered. 
The plains are intersected by numerous rivers, which the settlers 
divide into three classes: snow rivers, rain rivers and leakage rivers. 
The snow rivers, to which the Waimakariri, Rakaia, Ashburton and 
Rangitata belong, have their sources in the central chain. They 
are wild torrents issuing from the deep rock-bound gorges of the 
Alps, fed by the glaciers and melting snows, and are consequently 
subject to sudden and powerful freshes. They never dry during 
the autumn or summer months. The so-called rain rivers are those 
which have their origin in the outrunning spurs of the Alps, as, 
for example the Selwyn, Hinds, Ashley and others. One of their 
characteristic features is , that they generally dry up during the 
summer and autumn months, that to say, that they disappear in 
their course below the shingle , of which the plains are composed. 
The leakage rivers consist of those smaller water-courses which 
take their rise on the plains themselves, as for instance the Heatli- 
cote, Avon, Styx, Little Rakaia and many others. They are merely 
formed by the waters of the rivers of the former two classes, 
which, losing themselves among the shingle till they find imper- 
meable beds to arrest their further sinking, and on which they 
How downwards, form underground streams till forced to the 
surface by meeting a change of the strata. The water flowing from 
each of these outlets is remarkably uniform throughout the year, 
and is always beautifully clear. ' 
1 Great bodies of water are also seen to leave the channels of the main rivers, 
which entirely diappear under the surface and have no outlet any where on the 
plains. There is no doubt, that for instance the Waimakariri has many undergrouud 
streams travelling for long distances at different depths. One of them feeds the 
artesian wells in and around Christchurch. The water in all these wells has been 
reached at about 67 feet below high-water mark and rises to about 26 feet above 
