Abstract
THIS book is essentially different from James Geikie's “Structural and Field Geology,” which makes its appeal through its fine presentation of rocks as they actually appear on bare surfaces of the crust. The two works may well stand side by side. Prof. Bailey Willis concerns himself here with the mechanics of rock-displacement and rock-folding, and illustrates these by photographs of his series of models made to illustrate the structure of the Appalachians. He uses mixtures of wax, plaster, and turpentine, producing strata that yield very variously to mechanical stress. The deformation of an incompetent series under load provides material that returns, as it were, into the core of a rising arch formed by competent strata that can lift a load when laterally compressed, or into the core of a syncline when the competent series lies below them and is bent downwards, displacing matter in the depths (p. 148). Hence we have highly crumpled series between strata of more simple curvature. The shearing of materials in sediments as well as in schists, so that new parting-planes are set up, accompanied by thinning and elongation of the mass, is frequently brought before us in this stimulating volume. Moreover, we never lose sight of the tridimensional character of the structures described. There is a valuable chapter on field-methods, in which the author remarks (p. 28) that “the explorer should have the pluck of an American and the self-respect of a Chinese.” The book provides geologists with very pleasant reading.
Geologic Structures.
Bailey
Willis
By. Pp. xi + 295. (New York and London: McGraw-Hill Book Co. Inc., 1923.) 17s. 6d.
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C., G. Geologic Structures. Nature 112, 897 (1923). https://doi.org/10.1038/112897a0
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DOI: https://doi.org/10.1038/112897a0