ADVERTISEMENT. IX 
25. Water Resources of the State of New York, Part II. by George W. Rafter. 1899. 8°. 101-200 
3. 12 pi. 
26. Wells of Southern Indiana (Continuation of No. 21), by Frank Leverett. 1899. 8°. 64 pp. 
27. Operations at River Stations for 1898, Part I. 1899. 8°. 100 pp. 
28. Operations at River Stations for 1898. Part II. 1899. 8°. 101-200 pp. 
29. Wells and Windmills in Nebraska, by Erwiu 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 Porto 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. 
i preparation: 
34. Underground Waters of a Portion of Southeastern South Dakota, by James Edward Todd. 
35. Operations at River Stations, 1899, Part I. 
TOPOGRAPHIC MAP OF THE UNITED STATES. 
When, in 1882, the Geological Survey was directed by law to make a geologic map of the United 
ates, there was in existence no suitable topographic map to serve as a base for the geologic map. 
tie preparation of such a topographic map was therefore immediately begun. About one-fifth of the 
ea of the country, excluding Alaska, has now been thus mapped. The map is published in atlas 
eets, each sheet representing a small quadrangular district, as explained under the next heading, 
ae separate sheets are sold at 5 cents each when fewer than 100 copies are purchased, but when they 
e ordered in lots of 100 or more copies, whether of the same sheet or of different sheets, the price is 
:ents each. The mapped areas are widely scattered, nearly every State being represented. About 
sheets have been engraved and printed; they are tabulated by States in the Survey's " List of 
iblicatious," a pamphlet which may be had on application. 
The map sheets represent a great variety of topographic features, and with the aid of descriptive 
xt they can be used to illustrate topographic forms. This has led to the projection of an educational 
ries of topographic folios, for use wherever geography is taught in high schools, academies, and 
lieges. Of this series the first two folios have been issued, viz: 
I. Physiographic types, by Henry Gannett, 1898, folio, consisting of the following sheets and 4 pages 
descriptive text: Fargo (N. Dak. -Minn.), a region in youth; Charleston (W. Va.), a region in 
iturity ; Caldwell (Kans.), a region in old age; Palmyra (Va.), a rejuvenated region ; Mount Shasta 
al.), a young volcanic mountain; Eagle (Wis.), moraines; Sun Prairie (Wis.), drumlins; Donald- 
uville (La.), river flood plains; Boothbay (Me.), a fiord coast; Atlantic City (N. J.), a barrier-beach 
ast. 
1. Physiographic types, by Henry Gannett, 1900, folio, consisting of the following sheets and 11 pages 
descriptive text: Norfolk (Va.-N. C), a coast swamp; Marshall (Mo.), a graded river; Lexington 
ebr.), an overloaded stream; Harrisburg (Pa.), Appalachian ridges; Poteau Mountain (Ark.-Ind. 
), Ozark ridges; Marshall (Ark.), Ozark Plateau; West Denver (Colo.), hogbacks; Mount Taylor 
. Mex.), volcanic peaks, plateaus, and necks; Cucamonga (Cal.), alluvial cones; Crater Lake special 
reg.), 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 
ologic maps. The atlas is issued in parts, or folios, progressively as the surveys are extended, and 
designed ultimately to cover the entire country. 
Dnder the plan adopted the entire area of the country is divided into small rectangular districts 
isignated quadrangles), bounded by certain meridians and parallels. The unit of survey is also the 
it of publication, and the maps and descriptions of each rectangular district are issued as a folio of 
e Geologic Atlas. 
Each folio contains topographic, geologic, economic, and structural maps, together with textual 
acriptions and explanations, and is designated by the name of a principal town or of a prominent 
tural feature within the district. 
Two forms of issue have been adopted, a "library edition" and a "field edition." In both the 
eets are bound between heavy paper covers, but the library copies are permanently bound, while 
3 sheets and covers of the field copies are only temporarily wired together. 
Jnder the law a copy of each folio is sent to certain public libraries and educational institutions. 
ie remainder are sold at 25 cents each, except such as contain an unusual amount of matter, which 
i priced accordingly. Prepayment is obligatory. The folios ready for distribution are here listed. 
