National Geographic : 1898 Jul
344 THE TOPOGRAPHIC ATLAS OF THE UNITED STATES was applied in southeastern United States, where the important episodes in continental history are clearly recorded in the pla teaus and canyons of the Piedmont region, and where the minor movements are recorded in unconformities separating the de posits of the Coastal plain; it was applied most successfully in New England and elsewhere by Professor Davis, who reads earth history from topographic maps. Within a dozen years the prin ciple has been widely recognized among investigators, and has given birth to a science-Geomorphology or the New Geology. Thus far this line of learning has mainly been confined to a limited number of original investigators and teachers in high grade educational institutions, and has lain beyond the reach of the general school and the citizen ; but now Mr Gannett's trea tise, issued by a public office, brings this distinctively American advance in science within reach of the American public. The atlas comprises ten maps, of which the first three are de voted to the now well-known stages in topographic develop ment-youth, maturity, and old age. The fourth illustrates a rejuvenated region, typifying the Piedmont plateau. The fifth map represents a young volcanic mountain, its subject being our magnificent volcanic cone, Mount Shasta. Moraines and drumlins, representing characteristic phases of ice-work, are shown on the sixth and seventh sheets, and a fiord coast, with its picturesque record of ice-work half drowned in ocean, forms the subject of the ninth sheet. The two remaining sheets illus trate river flood-plains and a barrier-beach coast. The text in cludes an exposition of the conventions used in topographic mapping, and a full description of each of the sheets with a fuller interpretation of its features as records of geographic de velopment. The issue of this folio marks an epoch in geographic teaching. Hitherto teachers have been limited in their work to glittering generalities in the books, or to the maze of little-understood real ities in their sight; but now comes a series of American illustra tions, shown in such detail that any teacher may correlate the features with those of his own landscape, and these are inter preted by the hand of a master so clearly that even the average pupil cannot fail to read aright. The atlas folio may be obtained at the nominal price of 25 cents on application to the Director of the Geological Survey. WJM.