Publications

The concentration of dissolved solids in waters of streams of the Southwestern United Stated fluctuates widely as the stream discharge changes. These fluctuations may be extensive in a period of a few days or even a few hours. Data in this paper show the extent of the day‐to‐day changes in specific conductance and discharge of the Rio Grande at San Acacia, New Mexico, during the spring run‐off per

Iwo Jima, in the western Pacific Ocean, consists of Motoyama, a broad volcanic cone, at the north, and Mt. Suribachi at the south, with an undulating isthmus between. Motoyama is largely light-gray-buff tuff. A thick andesitic lava flow under Suribachi, exposed in several places, is overlain by a thick deposit of cinder and scoria. The isthmus (called Tidorigahara by the Japanese) is underlain by

Systematic surveys made at Bikini before and after the atomi bomb tests (Operation Crossroads) in the summer of 1946 afforded an unusual opportunity to examine the reefs and islands of one of the larger atolls of Micronesia. The existing reef appears to be developed on an older surface that extends as a terrace into the lagoon and beyond the seaward margin of the reef. A sketch map shows the distr

No abstract available.

Cryptocrystalline magnesite occurs as relatively small dense, white masses in a Tertiary volcanic tuff, here named the Currant tuff, in White Pine and Nye counties, 29 miles southwest of Ely, Nevada. The deposits are small, but some of the magnesite is of very high quality with almost no iron or aluminum. However, much of the magnesite is mixed with dolomite and calcite, and a serpentinelike miner

The rocks of Iwo Jima are augite and augite-hornblende trachyandesites, distinctly more alkalic than the ordinary andesites of Japanese volcanoes or the average world andesite. They are described, and chemical analyses are listed. Fumarolic gases have altered some rocks to a mixture of opal and clay minerals and have cemented tuff with opal, calcite, zeolite, and iron oxides.

Since 1946, the Committee has given consideration to terminology as related to the field of runoff. As the science of hydrology develops, there is increasing need for a more definite and uniform terminology in order to promote use of more precise language in technical literature. While it may not be possible or desirable at this time to standardize completely, it appears entirely possible to stand

The principal activity of the Committee during the year was the arranging and presentation of a symposium on methods of estimating ground‐water supplies. The response was gratifying and resulted in the presentation of 11 interesting papers at the 1946 meeting. The report of the Subcommittee on Permeability by C. E. Jacob, Chairman, is given as Appendix A. At a meeting of the Executive Committee of

The Edwards limestone, and to a lesser extent the Comanche Peak limestone and the lower part of the Glen Rose limestone below, all of Lower Cretaceous age, form one of the most extensive ground‐water reservoirs in Texas. As a result of normal faulting, these formations are connected by underground channels to form a hydrologic unit which is partly artesian and partly unconfined. Observations in Co

During the summer of 1946 the writer studied the ground‐water resources of Schoharie County, New York, as a part of the program of ground‐water investigation being carried on in cooperation between the United States Geological Survey and the New York State Water Power and Control Commission. Because the outcrop belt of Devonian and Upper Silurian carbonate rocks is wider in Schoharie County than i

The membership of the Committee has remained unchanged during the year. There has been some discussion of committee activities between individual members and in small groups. The further discussion of runoff terminology has resulted in no new developments of special note.The following statements have been received from members of the committee concerning activities of the agencies with which they

The basic principles of the idealized hydrologic cycle are reviewed with emphasis on storage and movement of water in the soil. A distinction is made between ground‐water runoff and overland runoff in terms of storage and lag, expressed as accumulated deviations from uniform flow over a period of several years. These functions are presented for the period 1920 through 1945 for three rivers in cent