ADVERTISEMENT. IX 
25. Water Resources of the State of New York, Tart 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 River Stations for 1898, Part I. 1899. 8 D . 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. AVater 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. Underground Waters of Southeastern South Dakota, by J. E. Todd. 1900. 8°. 34 pp. 19 pis. 
n -preparation: 
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 
itates, there was in existence no suitable topographic map to serve as a base for the geologic map. 
2he preparation of such a topographic map was therefore immediately begun. About one-fifth of the 
rea of the country, excluding Alaska, has now been thus mapped. The map is published in atlas 
heets, each sheet representing a small quadrangular district, as explained under the next heading, 
.'he separate sheets are sold at 5 cents each when fewer than 100 copies are purchased, but when they 
re ordered in lots of 100 or more copies, whether of the same sheet or of different sheets, the price is 
cents each. The mapped areas are widely scattered, nearly every State being represented. About 
00 sheets have been engraved and printed; they are tabulated by States in the Survey's " List of 
'ublications," a pamphlet which may be had on application. 
The map sheets represent a great variety of topographic features, and with the aid of descriptive 
ext they can be used to illustrate topographic forms. This has led to the projection of an educational 
eries of topographic folios, for use whereA-er geography is taught in high schools, academies, and 
olleges. 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 
f descriptive text: Fargo (N. Dak. -Minn.), a region in youth; Charleston (W. Ya.), a region in 
maturity: Caldwell (Ivans.), a region in old age; Palmyra (Va.), a rejuvenated region; Mount Shasta 
Cal.), a young volcanic mountain; Eagle (Wis.), moraines; San Prairie (Wis.), drumlins; Donald- 
onville (La.), river flood plains; Boothbay (Me.), a fiord coast; Atlantic City (N. J.), a barrier-beach 
oast. 
2. Physiographic types, by Henry Gannett, 1900, folio, consisting of the following sheets and 11 pages 
f descriptive text: Norfolk (Va.-N. C), a coast swamp; Marshall (Mo.), a graded river; Lexington 
v Nebr.), an overloaded stream; Harrisburg (Pa.), Appalachian ridges; Poteau Mountain (Ark.-Ind. 
?.), 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 
eologic maps. The atlas is issued in parts, or folios, progressively as the surveys are extended, and 
3 designed ultimately to cover the entire country. 
Under the plan adopted the entire area of the country is divided into small rectangular districts 
designated quadrangles), bounded by certain meridians and parallels. The unit of survey is also the 
;nit of publication, and the maps and descriptions of each rectangular district are issued as a folio of 
he Geologic Atlas. 
Each folio contains topographic, geologic, economic, and structural maps, together with textual 
escriptions and explanations, and is designated by the name of a principal town or of a prominent 
atural feature within the district. 
Two forms of issue have been adopted, a "library edition" and a "field edition." In both the 
heets are bound between heavy paper covers, but the library copies are permanently bound, while 
he sheets and covers of the field copies are only temporarily wired together. 
Under the law a copy of each folio is sent to certain public libraries and educational institutions, 
'he remainder are sold at 25 cents each, except such as contain an unusual amount of matter, which 
re priced accordingly. Prepayment is obligatory. The folios ready for distribution are here listed. 
