264 
SCOTT'S LAST EXPEDITION 
[May 
ductory lecture on his remarkably fascinating subject — 
modern physiography. 
These modern physiographers set out to explain the 
forms of land erosion on broad common-sense lines, heed- 
less of geological support. They must, in consequence, 
have their special language. River courses, they say, are 
not temporary — in the main they are archaic. In con- 
junction with land elevations they have worked through 
geographical cycles, perhaps many. In each geographical 
cycle they have advanced from infantile V-shaped forms ; 
the courses broaden and deepen, the bank slopes reduce in 
angle as maturer stages are reached until the level of sea 
surface is more and more nearly approximated. In senile 
stages the river is a broad sluggish stream flowing over 
a plain with little inequality of level. The cycle has 
formed a Peneplain. Subsequently, with fresh elevation, 
a new cycle is commenced. So much for the simple case, 
but in fact nearly all cases are modified by unequal 
elevations due to landslips, by variation in hardness of 
rock, &c. Hence modification in positions of river courses 
and the fact of different parts of a single river being in 
different stages of cycle. 
Taylor illustrated his explanations with examples : 
The Red River, Canada — Plain flat though elevated, 
water lies in pools, river flows in * V 9 ' infantile ' form. 
The Rhine Valley — The gorgeous scenery from Mainz 
down due to infantile form in recently elevated region. 
The Russian Plains — Examples of * senility.' 
- Greater complexity in the Blue Mountains — these are 
undoubted earth folds ; the Ncpean River flows through an 
