(1) Structural Geology (2) Geologischer Führer durch Nordwest-Sachsen (3) Australasian Fossils A Students' Manual of Palaeontology (4) Practical Instructions in the Search for, and the Determination of, the Useful Minerals, including the Rare Ores

Abstract

(I)MR. LEITH'S book does not cover so wide a field as Prof. James Geikie's “Structural and Field Geology”, which was reviewed in this journal in 1912 (vol. xc., p. 159), nor is it so attractive at first reading as Prof. Wilckens's “Grundzüge der tektonischen Geologie” (NATURE, vol. xcii., p. 564). But it represents the application of close thinking to the problems of earth-fracture and the displacement of rock-masses in regard to one another, and it forms a specialised manual for the student of all kinds of rock-flow. The large amount of sliding and differential movement that takes place between layers of the same contorted series may be well realised in the field; but it is not apparent in our ordinary diagrams. Mr. Leith, on p. 114 and elsewhere, very usefully directs attention to it, and connects the “dragfolds” seen on a small scale with the overfolded structure of the Alps. Willis's terms, “competent” and “incompetent”, which are too familiar in their ordinary usage, are adopted (p. iii) for layers of rock that respectively resist and yield to compound crumpling. A fold may exmbit “competence” up to a certain point, and may become “incompetent” on continuance of pressure, yielding in this case as a series of folds in which the successive beds are similarly curved. The book is full of matter that leads to accurate realisation, and includes useful reviews of such widely separated terminals of the subject as the origin of joints and the theory of isostasy.

(1) Structural Geology.

By C. K. Leith. Pp. viii + 169. (London: Constable and Co., Ltd.) Price 6s. 6d. net.

(2) Geologischer F hrer durch Nordwest—Sachsen.

By E. Krenkel. Pp. vii + 202 + 14 plates. (Berlin: Gebr der Borntraeger, 1914.) Price 4 marks.

(3) Australasian Fossils. A Students' Manual of Palaeontology.

By F. Chapman. With an introduction by Prof. E. W. Skeats. Pp. 341. (Melbourne and London: G. Robertson and Co. Propy., Ltd., 1914.)

(4) Practical Instructions in the Search for, and the Determination of, the Useful Minerals, including the Rare Ores.

By A. McLeod. Pp. ix + 114. (New York: J. Wiley and Sons, Inc.; London: Chapman and Hall, Ltd., ii.) Price 5s. 6d. net.