Reviews—Ries and Watson—Engineering Geology. 279 
given the prominent place it should occupy, and many a failure must 
be attributed to this defect; yet it is hardly possible, or indeed - 
necessary, for the average student to be as thoroughly grounded in 
the subject as the geological expert. How much, or how little, 
stratigraphical geology is necessary is perhaps a question. More is 
necessary for the mining than the civil engineer, but in any case 
enough facts should be known to recognize when the expert should 
be consulted. In the book under review the authors have succeeded 
well in selecting and discussing those geological principles and topics 
which have a special bearing upon civil engineering, and in most cases 
have been able to illustrate their points by reference to actual 
occurrences in the United States. 
In the first part of the book, which deals with rocks and rock- 
forming minerals, the igneous rocks are classified chiefly by their mega- 
scopic and microscopic characters, chemical relations being indicated 
only by silica percentages. A simpler and clearer classification would 
have been one in which the hypabyssal are separated from the 
plutonic rocks, on the lines followed by Harker. ‘he classification 
taken from Kemp is far too complex, and more suitable to the 
requirements of a petrologist than an engineer. 
A valuable chapter is that devoted to underground waters, which 
will be read with equal advantage by both geologists and engineers. 
The excellent water-supply papers of the United States Geological 
Survey have been freely drawn upon, and the results of much 
detailed work are here assembled in concise form applicable to this 
country as well as the States. Landslides, which are often of mere 
academic interest to the geologist, bulk largely in the eyes of the 
engineer, and receive adequate treatment. A useful table is given.of 
the slopes that should be adopted in cuts of different depths to avoid 
sliding. In chapter viii problems of harbour and _ river-mouth 
improvement are discussed and many cases cited in illustration. 
In describing glacial deposits it is shown how necessary it is that 
the drifts should be mapped, and records of their varying thicknesses 
and composition recorded whenever possible, if only from the 
financial point of view. The problem of dealing with glaciers 
actively interfering with railroad construction does not arise in the , 
British Isles. In one case, where the Allen Glacier was found to 
project across the Copper River Valley in Alaska, the engineers 
blasted out a grade across 54 miles of stagnant, moraine-veneered, 
tree-covered ice. Ice lies beneath the ties, and future melting or 
advance will cause trouble and repeated repairs. 
Building-stones, limes, cements, clay, and road materials are next 
described. The importance of testing the durability of a stone is 
emphasized, although this quality is often relegated to the back- 
ground. Too.much importance can be attached to crushing strength, 
for in practically no case is a block of stone required to support 
a weight approaching anywhere near its limit of strength. It is 
stated that the use of basalt as a building-stone is not widespread ; 
we may recall that it has been used with some success in this 
country as a facing for sea-walls. 
Coal, petroleum, natural gas, and ore-deposits also receive adequate 
