ADVERTISEMENT. IX 
25. WaterResourcesof the State of New York, Part II, by G.W. Rafter. 1899. 8°. 101-200 pp. 12 pi. 
26. Wells of Southern Indiana (Continuation of No. 21 ), by Frank Leverett. 1899. 8°. 64 pp. 
27. Operations at Biver Stations for 1898, Part I. 1899. S°. 100 pp. 
28. Operations at River Stations for 1898, Part II. 1899. 8 \ 101-200 pp. 
29. Wells and Windmills in Nebraska, by Erwin H. Barbour. 1899. 8°. 85 pp. 27 pi. 
30. Water Resources of the Lower Peninsula of Michigan, by Alfred C. Lane. 1899. 8°. 97 pp. 7 pi. 
31. Lower Michigan Mineral Waters, by Alfred C. Lane. 1899. 8°. 97 pp. 4 pi. 
32. Water Resources of Puerto Rico, by Herbert M. Wilson. 1899. 8°. 48 pp. 17 pi. 
33. Storage of Water on Gila River, Arizona, by Joseph B. Lippincott. 1900. 8°. 98 pp. 33 pi. 
34. Geology and water resources of SE. South Dakota, by J. E. Todd. 1900. 8°. 34 pp. 19 pis. 
In 2)reparation: 
35. Operations at River Stations, 1899, Part I. 
36. Operations at River Stations, 1899, Part II. 
37. Operations at River Stations, 1899, Part III. 
TOPOGRAPHIC MAP OF THE UNITED STATES. 
When, in 1882, the Geological Survey was directed by law to make a geologic map of the United 
States, there was in existence no suitable topographic map to serve as a base for the geologic map. 
The preparation of such a topographic map was therefore immediately begun. About one-fifth of the 
area of the country, excluding Alaska, has now been thus mapped. The map is published in atlas 
sheets, each sheet representing a small quadrangular district, as explained under the next heading. 
The separate sheets are sold at 5 cents each when fewer than 100 copies are purchased, but when they 
are ordered in lots of 100 or more copies, whether of the same sheet or of different sheets, the price is 
2 cents each. The mapped areas are widely scattered, nearly every State being represented. About 
900 sheets have been engraved and printed; they are tabulated by States in the Survey's " List of 
Publications," a pamphlet which may be had on application. 
The map sheets represent a great variety of topographic features, and with the aid of descriptive 
text they can be used to illustrate topographic forms. This has led to the projection of an educational 
series of topographic folios, for use wherever geography is taught in high schools, academies, and 
colleges. Of this series the first two folios have been issued, viz: 
1. Physiographic types, by Henry Gannett, 1898, folio, consisting of the following sheets and 4 pages 
of descriptive text: Fargo (N. Dak. -Minn.), a region in youth; Charleston (W. Va.), a region in 
maturity; Caldwell (Kans.), a region in old age; Palmyra (Va.), a rejuvenated region ; Mount Shasta 
(Cal.), a young volcanic mountain; Eagle (Wis.), moraines; Sun Prairie (Wis.), drumlins; Donald- 
sonville (La.), river flood plains; Boothbay (Me.), a fiord coast; Atlantic City (N. J.), a barrier-beach 
2. Physiographic types, by Henry Gannett, 1900, folio, consisting of the following sheets and 11 pages 
of descriptive text: Norfolk (Ya.-N. C), a coast swamp; Marshall (Mo.), a graded river; Lexington 
(Nebr.), an overloaded stream; Harrisburg (Pa.), Appalachian ridges; Poteau Mountain (Ark.-Ind. 
T.), Ozark ridges; Marshall (Ark.), Ozark Plateau; West Denver (Colo.), hogbacks; Mount Taylor 
(N. Mex.), volcanic peaks, plateaus, and necks; Cucamonga (Cal.), alluvial cones; Crater Lake special 
(Oreg.), a crater. 
GEOLOGIC ATLAS OF THE UNITED STATES. 
The Geologic Atlas of the United States is the final form of publication of the topographic and 
geologic maps. The atlas is issued in parts, or folios, progressively as the surveys are extended, and 
is designed ultimately to cover the entire country. 
Under the plan adopted the entire area of the country is divided into small rectangular districts 
(designated qvadr angles), bounded by certain meridians and parallels. The unit of survey is also the 
unit of publication, and the maps and descriptions of each rectangular district are issued as a folio of 
the Geologic Atlas. 
Each folio contains topographic, geologic, economic, and structural maps, together with textual 
descriptions and explanations, and is designated by the name of a principal town or of a prominent 
natural feature within the district. 
Two forms of issue have been adopted, a "library edition" and a "field edition." In both the 
sheets are bound between heavy paper covers, but tho library copies are permanently bound, while 
the sheets and covers of the field copies are only temporarily wired together. ^ m 
Under the law a copy of each folio is sent to certain public libraries and educational institutions. 
The remainder are sold at 25 cents each, except such as contain an unusual amount of matter, which 
are priced accordingly. Prepayment is obligatory. Tho folios ready for distribution are here listed. 
