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W. O. Smith

Publications and source records attributed to W. O. Smith.

6 recordsLinked to original sources
USGS2014

Pedological relations of infiltration phenomena

An attempt is made to outline the principal features which are to be considered in infiltration problems. The need for consideration of genetic and morphological relations is emphasized, especially the view that the latter is a boundary condition for the quantitative procedures usually derived from the former. Detailed development of infiltration relations are given for the more usual genetic profiles. The role of soil structure in infiltration phenomena is developed in considerable detail. A discussion of fragmented soils is also given. A brief discussion of the physical mechanisms involved in infiltration develops the viewpoint that not only porosity and texture but also soil structure and moisture content are usually sufficient to define infiltration phenomena.

Eos, Transactions, American Geophysical Union↗
USGS2014

Discussion of “pedological relations of infiltration phenomena”

Smith provides an illuminating consideration of infiltration through soil in relation to the structure and texture of the soil its moisture content, and the variation of infiltration for A, B, and C soil zones. The organic nature of soil might also be stressed. Rotting rootlets provide passageways for water in addition to physical structure and texture. The impression is gained that mechanical treatment, such as plowing and harrowing, general decreases the infiltration capacity of soil, through destruction of surface structure, and fragmentation. This appears true of the soil in the physical sense. Equally true, in a plowed soil, may be the formation of puddling colloids after a rain, through the breaking of natural granules into fragments. However, the surface infiltration is increased by plowing and harrowing through the turnover of the sod layer composed of grasses and weeds. Smith does not consider the sod layer as a soil zone, yet it is the first barrier that precipitation must pass before it enters the structural crevices and textural pores of the soil. Although a dense sod layer usually does not increase runoff because of its retentive nature, it increases interception, and hence evaporation, so unless the sod is economic, the water is lost anyway.

Eos, Transactions, American Geophysical Union↗
USGS1958

Recent underwater surveys using low-frequency sound to locate shallow bedrock

Underwater investigations at Lake Mead, Chicago, Passamaquoddy Bay, and on Long Island established the characteristics of sound waves that can be used in shallow geophysical exploration by the sonar method. At Lake Mead the sediments were for the most part clay of high water content which was easily penetrated by low-power sound at a frequency of 14.2 kilocycles. The greatest depth of penetration was 140 feet. Sound having frequencies of 50 and 80 kilocycles did not penetrate. At Chicago, sound at a frequecy of 11 kilocycles and an output power of 800 watts gave a satisfactory delineation of bedrock beneath Lake Michigan. The maximum distance to bedrock was about 135 feet. At Passamaquoddy Bay a sound frequency of 6 kilocycles and about 700 watts of output power gave much better delineation of bedrock. A frequency of 6 kilocycles at the lower output power was much better than 11 kilocycles at higher power. About 250 feet of penetration was attained. Pulsed power was used in each of these investigations. The pulse lengths were long—about 14–25 milliseconds. Bedrock was mapped at Lake Mead, Chicago, and Passamaquoddy Bay. The methods of ordinary hydrographic surveying were used for horizontal and vertical positioning. For horizontal positions the ordinary three-point sextant-fix method was used. For vertical positioning, recording gages suitably placed and supplemented by staff gages were used. All data were tied into the third-order control net of the U. S. Coast and Geodetic Survey. In connection with a study for a proposed Midwestern waterway, the technical problem was reviewed and the techniques considerably improved. New equipment was built and evaluated on Long Island Sound. It operated with pulsed power at a frequency of 6 kilocycles, and pulse length was controlled and variable from 1 to 9 milliseconds. Output acoustic power was about 2500 watts. With the transducer in ordinary operating positions as much as 400 feet of sediment was penetrated. With the transducer placed directly on the bottom of the water in Huntington Bay about 750 feet of penetration was attained. Several innovations in sonar techniques, which are desirable for sediment exploration, and which give much more detailed information than the earlier equipment are described. The techniques required for stratigraphic interpretation of the sound records are described briefly. A method for the determination of sound velocities is discussed. Multiple echoes and other effects complicate the interpretation of records and are explained. The problems of geological control encountered also are mentioned.

Illinois, Maine, Nevada, New Brunswick, New York↗