The New Student's Reference Work/Geological Survey
Ge′olog′ical Survey, United States, is a bureau that was organized by the Department of the Interior in 1879 to bring together the scattered surveys of many western districts and construct geological maps of the United States. The bureau continues to pursue its investigations concerning the products of the country, its mineral resources and the means and possibilities of irrigation. The maps are made in such detail that the scale is never less than four miles to the inch; and is often as large as one mile to the inch. The heights of places are shown by lines, called contours, which represent an equal distance above sea-level. The maps, as they are made, are at once published in folios. The director of the survey issues an annual report. Full information upon the work of the bureau may be gained from the reports of the director, together with Walcott's The United States Geological Survey, Washington, 1895.