National Geographic : 1898 Jul
THE TOPOGRAPHIC ATLAS OF THE UNITED STATES " In 1882 the United States Geological Survey began the con struction of a topographic map of the country. The work has now been in progress fourteen years, and about 600,000 square miles have been mapped. The areas shown on these maps are scattered widely over the country and represent a great variety of topographic features, and the map sheets, with the aid of de scriptive text, can be used to illustrate topographic forms. This led the Director to propose the publication of an educational series of folios, for use wherever geography is taught in high schools, academies, and colleges. Authority for their publica tion and sale was granted by Congress in an act approved March 2, 1895. . . . The first folio of the series presents on ten maps illustrations of some of the simplest and most character istic types of topography to be found in those parts of the United States which have thus far been mapped. Succeeding folios will illustrate more complex forms." So Henry Gannett, Geographer of the United States Geolog ical Survey, introduces an illustrated treatise in folio form on the " Land Forms of the United States." * When geographic exploration brought to the knowledge of men the unparalleled Grand Canyon of the Colorado and the picturesque plateau country adjacent, the way was prepared for the discovery of new principles in geographic development; in good time Powell descended the Canyon, and he and his collab orators surveyed the plateau country, and as the work pro gressed the " baselevel of erosion " was recognized. The idea quickly took root, and grew into one of the fundamental princi ples of earth-science; spreading eastward into provinces already reconnoitered or surveyed, it was found to afford a new means for interpreting earth-history, and thereafter the later stages in the geographic development of the continent were read from land forms as well as from fossil plants and animals. The principle * Department of the Interior IUnited States Geological Survey I Charles D. Walcott, Director I - ITopographic Atlas I of the ]United States IPhysiographic Types I by I Henry Gannett - I [List of Contents, etc.] | Folio 1 Physiography I Washington, D. C. IEngraved and printed by the U. S. Geological Survey I S. J. Ktibel, Chief En graver 1898.