NOTE.—These maps, projected without reference to political divisions, are designated by some prominent feature found on them. They are of uniform size—16 by 20 inches, on a scale of 1:62500, or about 1 mile to 1 linear inch on the map. They are issued as working editions for the use of geologists of the United States Geological Survey and are not published for general distribution or for sale. About 900 sheets have been produced since 1883, covering more or less nearly every Stale and Territory. Massachusetts. Rhode Island, New Jersey, and the District of Columbia are completely mapped. Some of the earlier maps are on a scale of 1:125000 and 1:250000.