Page:The Journal of geology (IA journalofgeology11893univ).pdf/312

The United States Geological Survey is to be congratulated upon the appearance of the first atlas sheets of the geological map of the United States which, although still considered as preliminary to the regular edition, may be taken as essentially finished, and as embodying the chief features which will characterize the completed work. Each atlas consists of one portion of the whole map printed in four ways: one presenting the topography by itself; one, the areal geology; another, the geological structure by means of cross sections, and a fourth, the features of economic importance. Accompanying these are sheets of text, one of which explains certain elementary concepts of the science and defines the sense in which some of the more common terms are to be employed throughout this series of publications. The text describing the special area surveyed is admirably prepared to set forth in a concise manner the leading features of the geology and of the economic resources. It is prefaced in some cases by a general sketch of the region immediately surrounding the area published, which aids materially the comprehension of the more local geology. In one instance, however, the sketch embraces nearly the whole eastern portion of the United States, which seems unnecessary since, we assume, it is not the intention of the Survey to do away with the publication of its monographs and bulletins, where the full results of the several investigations should appear. Otherwise, the text accompanying the atlas sheets would be insufficient.

The sheets finished are from widely separated parts of the country: the Hawley sheet in Massachusetts, the geology of which is by Professor B. K. Emerson; the Kingston sheet in Tennessee, the geology by Mr. C. Willard Hayes, assisted by