Reviews—Professor Bonney—On certain Channels. 229 
is exemplified in Bulletin 57, A Geological Reconnaissance of a portion 
of the Murchison Goldfield, by H. P. Woodward. We are told that 
the area dealt with embraced 3,300 square miles, and that the work 
was carried out chiefly in 1912 with some unavoidable interruption. 
The country consists chiefly of granite, with ancient crystalline 
schists, and shows wonderful examples of arid erosion, many of which 
are figured. The bulletin contains an account of the economic 
geology of the area, including two tin fields, an occurrence of 
emeralds, and aboriginal ochre mining. The emeralds are derived 
from pegmatite veins cutting mica-schists, and the occurrence is 
of value as the gem is now very scarce. 
Bulletin No. 59 is a collection of Miscellaneous Reports containing 
eighteen short papers, mostly preliminary observations on various 
ore-bearing areas of the State, issued in this form so as to ensure 
prompt publication of the valuable mining information they contain. 
Gold is, of course, the main quest; but occurrences of tin, lead, 
copper, coal, and rare metals are also dealt with in this bulletin. 
There are also two petrological papers, and one on Western Australian 
meteorites. 
Cowan: 
VI.—Ow cerrain CHANNELS ATTRIBUTED 10 OVERFLOW STREAMS FROM 
Icz-pammep Laxrs. By Professor T. G. Bonnny, F.R.S. pp. 44. 
Cambridge: Bowes & Bowes. 1915. Price 1s. 
LTHOUGH Professor Kendall’s explanation of the so-called 
overflow channels of the Cleveland district has been applied to 
similar phenomena in East Lothian, Cumberland, Dublin, and 
elsewhere, a number of objections of a general character have been 
raised from time to time. In the Presidential Address to the British 
Association in 1910 Professor Bonney stated the difficulties involved 
in the “‘land-ice theory’, and in the pamphlet under review these 
difficulties are reiterated and the result of a detailed examination of 
several of the above-mentioned localities discussed. Although at the 
present day marginal lakes are uncommon, most of the Alpine 
examples being small and possessing no overflow channels, certain 
criteria such as beaches, deltas, floor-deposits, and overflow channels 
are considered to be indicative of the former presence of such lakes. 
In the case of Glen Roy the evidence consists mainly of the first two, 
but in the North of England the last is the only significant criterion. 
Professor Bonney holds that the ‘railway cutting’ trenches must 
have been cut by mature rivers, and that their form is not such as 
would be expected from lake overflows, even where the latter would 
carry much debris. He prefers to consider them as the ‘‘ relics of 
ancient, sometimes very ancient, valley systems and not such modern 
features as the glacial theory demands”. Various facts seem to 
favour this hypothesis: for example, the channels sometimes occur in 
an aligned series, while they are often cut by later transverse streams. 
Again, overflows would tend to be spasmodic, while the resultant 
trenches would, like Alpine sub-glacial streams, tend to be V-shaped. 
The absence of deltas seems significant, since overflow streams would 
