26 Physical Geography. E 
ı500om. They consist, according to MARSHALL, of large intrusive granite masses 
on the western side but on the eastern sediments of Ordovician and Silurian 
‚age, schists and marbles extend for a distance of 32 km. Banks Peninsula 
on the E. of Canterbury is formed of much denuded volcanic rocks of Tertiary 
age reaching a maximum height of about 900 m. 
Plains. Gravel plains formed by glacial or snow rivers are a striking 
feature of. South Island topography. The most important are: — The Canter- 
bury Plain (161 km long by 48 km wide at its widest); the long narrow West- 
land coastal plain (200 km long by ıo km wide) and the Southland Plain 
extending from the lakes to Foveaux Strait. Flat as the Canterbury Plain 
appears to the eye, the surface near the foot-hills of the Southern Alps is 
more than 457 m above sea-level. Borings for artesian water shew by the 
peat-deposits at different depths that there have been several changes in the 
land-surface during the formation of the plain. 
Rivers. The numerous rivers issuing from the glaciers or fed by melting 
snows or frequent downpours are torrential at first their beds full of huge 
rocks over which the waters leap and foam. By degrees, the valleys shaped 
by former glaciers, widen and are filled from side to side, it may be, by a 
flat stony bed over which, in anastomosing streams, the river wanders. Lower 
down, as the valley widens still more, or when the plain is gained, the river 
may flow between high permanent terraces that it has built, and frequently 
there is a series of such at different levels with portions of the ancient flood- 
plains at their bases. River-beds ı km or more wide with terraces on either 
side are a common feature of the gravel-plains. / 
Where a tributary stream in a mountain-valley joins a river the shingle 
of its bed spreads out as a fan. Such are present at the mouth of almost 
every gully, sometimes naked and active, at other times plant-clad and passive. 
Former Glaciation. Equally important both physiographically and ecolog- 
ically is the question of the extent of the former glaciation, a matter regarding 
which geologists are not in accord. PARK holds that the ancient glaciers &- 
tended on the E. throughout the South Island to the present coast-line, but 
MARSHALL is of opinion that, except near Taieri Mouth, they did not go beyond 
the river-valleys (ıgı1: 31). Be this as it may, the mountain landscape 
furnishes absolute proof of a most extensive glaciation with its ancient moraines 
of great size, roches moutonnees, ice-shorn hillsides, truncated spurs and 
U-shaped valleys. Glacial lakes too Are frequent from small tarnıs on moraines t0 
the great sheets of water, frequently extremely deep, of Otago and Canterbury. 4 
PARK has also attempted to prove that the glaciation extended to the 
North Island, but his views are not, as yet, accepted by geologists in general. 
The gradual decrease in self-evident glacial features of the landscape from the 
Waimakariri valley northwards, the presence of moraines in the Lord Auckland 
Islands only on the hills, and the absence of moraines and ice-scratched rock 
on the North Island Dividing Range, let alone much adverse in 
Span the gravest doubts on Parks views. 
