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Dissolved mineral matter in surface‐waters

The only unpublished comprehensive Geological Survey records of dissolved matter in surface‐waters are the results obtained in the study of the Colorado River and its tributaries since 1930. The records are mainly analyses of 10‐day composites of daily samples, although there are several analyses of spot‐samples from some streams in the basin and about 4000 single determinations of chloride or sulphate in daily samples. The need for a large number of analyses is shown by the fact that during the period 1925–35 the quantity of dissolved solids in 10‐day composites from the Colorado River at Grand Canyon ranged from 226 parts per million for June 11–20, 1929, to 1889 parts per million for. September 21–30, 1934. A series of analyses covering a whole year might be misleading. The weighted averages for the different years ranged from 491 parts per million for the year ending September 30, 1928, to 960 for the year ending September 30, 1934.

Eos, Transactions, American Geophysical Union

Movement of ground‐water

The movement of water through formations having capillary openings is generally laminar and obeys Darcy's law, at least down to very low gradients. About 1000 samples tested in the laboratory of the United States Geological Survey have coefficients of permeability ranging from 0.001 to 90,000, indicating probable velocities ranging from a fraction of a foot to a few miles in a year. The Thiem field‐method gives promising results for determining permeability. Movement through sub‐capillary openings is important but poorly understood; molecular attraction of the water offers great resistance to movement or compression.

Eos, Transactions, American Geophysical Union

The diurnal fluctuation in the ground‐water and flow of the Santa Ana River and its meaning

In the time alloted for this subject it will be impossible to discuss, in its entirety, all phases of the methods used in computing the loss of water by transpiration from native plant‐life along the Santa Ana River. The results of this work are published in Bulletin 44 of the Division of Water Resources, State of California. The present paper is confined to a discussion of the diurnal fluctuations that occur in the flow of the Santa Ana River and the adjacent ground‐water. On Figure 1 have, been plotted the gage‐height records for a short period (July 5–8, 1935) for eight southern California streams. These records have been selected at random from the large number of records filed in the local office of the United States Geological Survey. Some of these streams have a large drainage‐area, others are small; some are short and steep, others flat and long. The points of measurement range from 15 to 2950 feet above sea‐level. One of the streams (Mojave River) is in the desert‐region; the others drain into the Pacific Ocean. The object of Figure 1 is to demonstrate, that the diurnal fluctuation exists and is, to a large degree, similar at most points of measurement. As a rule, the maximum discharge occurs about 10 o'clock in the morning, and the minimum late in the afternoon. It is readily recognized that these fluctuations are in the main caused by the evaporation and transpiration‐loss in or adjacent to the stream‐channel.

California

Extension of normals by precipitation‐data and by comparison with another stream

The factors affecting relationship between precipitation and consequent runoff are multitudinous and their interrelation is exceedingly complex. They vary widely from time to time and place to place. Basic data are meager and the weight to be given to any single factor is usually uncertain. Runoff‐characteristics of drainage‐areas within the same region will frequently be quite dissimilar. Under these circumstances no one should hope to answer conclusively paragraph V(a) of the questionnaire submitted January 4, 1935 by the Conference.

Eos, Transactions, American Geophysical Union

On the estimation of temperatures at moderate depths in the crust of the Earth

The modern deep well makes it possible to determine the temperatures of the rocks to depths exceeding two miles, and the rock‐samples obtained at these great depths enable the geologist to estimate the depths to the deeply buried basement‐rocks to a rather high degree of precision. The latter estimates are now being supplemented to a certain extent by the precision‐measurements of geophysicist, so that reliable data seem to be assured even in those areas in which the basement rocks are not reached by the drill. With these two sources of information at our disposal—accurate temperature‐measurements and reliable estimates or measurements of depths to bed‐rock—it should be possible to construct a rather accurate subsurface map showing the temperatures on the boundary‐surface between the sedimentaries and the basement floor. In this paper it is proposed chiefly to outline the method of procedure by making some rough calculations of the temperatures at great depths for a few locations in the United States and for one location near Carnarvon, Cape Province, South Africa.

Eos, Transactions, American Geophysical Union

Amygdales in Columbia River lavas near Freedom, Idaho

Incomplete study of seven amygdales from the Columbia River lava‐flows along Slate Creek, a tributary of Salmon River, near Freedom in north‐central Idaho, reveals that these small objects are of unusual geological and mineralogical interest. This paper includes an outline of the geology of the area from which the amygdales came, a description of the amygdales, and a brief account of the periodic tilting of a large fault‐block as revealed by them. Slate Creek enters Salmon River near the eastern border of the Columbia Plateau. In this locality the thick Lower Middle Miocene lava‐flows of the plateau country are interbedded with the sediments of many local lakes formed periodically as successive flows dammed the streams flowing westward from the higher country to the east. A section measured near the mouth of Slate Creek shows the volcanic rocks there to be 2600 feet thick. At some places on the Plateau farther from its borders the flows aggregate more than twice that thickness.

Eos, Transactions, American Geophysical Union

Extraordinary topaz‐replacement body in the Brewer Mine, South Carolina

A large body of massive topaz forms a part of the gold‐bearing lode at the Brewer Mine, South Carolina. This gold‐mine was opened 100 years ago and merits the distinction of being one of the early gold‐discoveries of the Southern Appalachian Region. The Brewer Mine is located near Jefferson, in Chesterfield County, near the northern boundary of South Carolina, and on the eastern edge of the Piedmont Province. The country rock is described by J. T. Pardee and C. F. Park, Jr., (Gold‐deposits of the Southern Appalachians, U. S. Geol. Surv. Prof. Paper, in preparation) as a quartz‐sericite schist that locally preserves the structure of a fine‐grained, waterlaid tuff, probably a rhyolite,from which it was derived. Exposures of granite that intrude the schist appear on the north and west at distances of a mile to a mile and a half.

South Carolina

The problem of the Chelmsford, Massachusetts, Granite

The Chelmsford granite is quarried in and around Oak Hill, about six miles west of Lowell, Massachusetts. The granite‐area is about eight miles long and one to three miles wide, and its longer dimension has a northeast bearing which is parallel with the regional axis of foliation in the country rock. The writer favors a hypothesis that much of the granite represents granitization of biotite schist under hydro‐magmatic invasion, and under stress that was insufficient to deform or distort the preexisting country rock‐structures to any marked degree. Banding of the granite is due chiefly, to variable amounts of biotite. The bands are thin and remarkably uniform. The banding, attitudes of schist inclusions, and distribution of the entire mass con form to the regional structural elements. Lit‐par‐lit injection‐bands are not clearly discernible although many of the light‐colored bands are doubtless of such origin. The absence of flow‐schlieren is noted. Petrographic evidence shows a remarkable amount of metasomatic fabric. Undoubted primary granitic texture is practically wanting. There is a high degree of orientation of biotite, muscovite, and groups of small mosaic quartz‐grains. The contacts of inclusions with adjacent granite‐bands are very irregular and interpenetrative, and granitic material also penetrates intricately along schistosity planes within the inclusions. Large irregular feldspar porphyroblasts and strings of such grains are distributed through the inclusions, generally with decreasing concentration toward the centers. Pegmatite and quartz veins, some of which carry much tourmaline, are abundant in some of the quarries. Crystallization zoning of feldspars is very rare. Feldspars are of three generations: (1) Early polysynthetically twinned porphyroblasts and irregular groundmass grains of oligoclase or albite‐oligoclase; (2) microcline and orthoclase, chiefly as porphyroblasts, and in part replacing the earlier plagioclase; and (3) albite and albite‐oligoclase, untwinned and mottled, as individual crystals, streaks, patches, and porphyroblasts, replacing microcline, quartz, and mica. Incomplete twinning, corrosion‐contacts, optical anomalies, inclusions of minerals, pseudo‐perthitic and myrmekitlc grains are among the diagnostic petrographic features that contribute to the theory of replacement.

Massachusetts

Report of the committee on glaciers, 1936–37

The Committee was enlarged during the past year by one more member, Prof. J. E. Church of Reno, Nevada, Chairman of the Committee on Snow, who agreed to serve on it while the Chairman of the Committee on Glaciers in turn accepted membership on the Committee on Snow. Thus the two Committees, whose spheres of work are in some respects intimately related, have been brought into closer touch with each other. Although the Committee on Glaciers has assembled considerable data on different lines of glaciologic research during the past few years, it seems best to confine this report, like the preceding ones, to a record of the variations—advance or recession—of glaciers in the continental United States and Alaska, and to reserve the other data for presentation later, in separate papers. The variations of glaciers here reported are for the 12‐month period from the autumn of 1935 to the autumn of 1936.

Eos, Transactions, American Geophysical Union

Report of the committee on runoff, 1936–37

Since the last meeting of the Section of Hydrology there has been a change in the organization and membership of some of the research‐committees, one relating to rainfall, of which Merrill Bernard is Chairman, and one relating to runoff, were created to replace the one committee which had functioned heretofore on both rainfall and runoff. This action by the officers provides for greater participation of the members of the Section in committees, and is a step well worth while. The personnel of the Committee as of May 1, 1937, is as follows: H. K. Barrows R. W. Davenport I. E. Houk F. T. Mavis F. F. Snyder M. M. Bernard R. S. Goodridge W. G. Hoyt A. F. Meyer H. C. Troxell E. S. Cullings R. E. Horton Joseph Jacobs C. R. Pettis C. O. Wisler I consider it an honor to act as Chairman of the Committee on Runoff but regret, however, that I have been unable as yet to coordinate thoroughly the work of the Committee or to inform myself adequately on many runoff‐experiments and research‐problems. Consequently, my report will be very brief and informal.

Eos, Transactions, American Geophysical Union

Report of the committee on underground waters, 1936–37

In accordance with the by‐laws of the Section, the Committee on Underground Waters has been reconstituted during the past year. With their research interests turning to other subjects, several members have dropped out, and four new men have been appointed. In order to maintain contact with the work of related committees, Charles H. Lee, Chairman of the Committee on Absorption and Transpiration, and C. S. Howard, Chairman of the Committee on Cnemistry of Natural Waters, have become members of the Committee on Underground Waters. The personnel of the Committee is as follows: H. F. Blaney C. S. Howard M. M. Leighton H. E. Simpson G. M. Fair F. H. Lahee O. E. Meinzer A. C. Swinnerton Willard Gardner C. H. Lee A. M. Piper D. G. Thompson, Chairman.

Eos, Transactions, American Geophysical Union

Appendix A—A selected list of papers relating to ground‐water hydrology

In the following list, brief‐statements have been added to certain references to call attention to special phases of ground‐water problems which are not apparent from the titles. Abstracts of most of the papers have been or will be published in the Annotated Bibliography of Economic Geology.

Eos, Transactions, American Geophysical Union

Resistivity‐studies of some salt‐water boundaries in the Hawaiian Islands

In the course of a systematic survey of the ground‐water resources of the Hawaiian Islands which is being made under the direction of H. T. Stearns of the United States Geological Survey in cooperation with the Territorial Government of Hawaii, it was found desirable to test the utility of geophysical methods in the solution of certain Hawaiian water‐supply problems. A cooperative geophysical survey for this purpose was undertaken by the Geophysical Section, then with the Bureau of Mines but later transferred to the Geological Survey, during the course of which a series of resistivity‐studies of certain salt‐water boundaries was begun. Since the location of such boundaries is of considerable importance in many areas it has been thought worth while to present the results which have thus far been obtained.

Eos, Transactions, American Geophysical Union

The use of resistivity‐methods in the location of salt‐water bodies in the El Paso, Texas, Area

During 1935 and 1936 the Ground‐Water Division of the United States Geological Survey made an investigation of the ground‐water resources of the El Paso, Texas, Area. Geological and hydrological studies comprised the principal part of the investigation, and these studies were supplemented by measurements of earth‐resistivity made largely by the Geophysical Section of the Geological Survey along traverses aggregating 51 miles. The extent to which resistivity‐methods may be useful in ground‐water work has been the subject of much discussion. A full evaluation of the method can not be made at this time. However, the work in the El Paso Area indicates that the presence of faults and of underground bodies of salt water may be definitely determined by resistivity‐measurements.

Texas

Results to be expected from resistivity‐measurements

The work described in this paper was all done in connection with dam‐site investigations and was not directly connected with hydrology. However, geophysics is coming to have a place in hydrologic investigations, and these results may throw some light on what can be accomplished by resistivity‐measurements. We have found that,for many questions not involving exact determinations of depth, resistivity‐ measurements give conclusive answers. Ordinarily a reliable answer can be expected to the question of the existence of a buried channel if the covering is composed of unconsolidated material with a resistivity differing from that of the rock. For example, topographic surveys were made at two alternative dam‐sites on a river about four miles apart. Examination of the surface‐geology indicated that a channel burled under glacial debris possibly existed at each site, but resistivity‐measurements proved that such a channel existed at one site and not at the other. On the other hand, at another site the geologist suspected there might be an old channel on a steep side hill. Geophysical measurements showed a depth of overburden of 46 feet and showed that if a deeper channel exists it must be narrow; but they did not show positively that no such channel exists. Probably a careful survey with a large number of lines would have given a more definite answer, but the rough topography interfered with the resistivity‐work, and time and money were not available for a detailed survey. After completion of the geophysical work, the geologist located some outcrops which led him to conclude that no old channel exists at this site. At two other dam‐sites in Oregon resistivity‐measurements showed that there were no burled channels.

Eos, Transactions, American Geophysical Union

The mutual interference of artesian wells on Long Island, New York

The withdrawal of water from a well necessarily produces a drop in water‐level in the well. The ground‐water level in the vicinity of the well from which the water is withdrawn likewise declines, but the amount of decline decreases with increasing distance from the well, so that a cone of depression of the water‐surface in the vicinity of the well is produced. The cone of depression is an actual water‐surface if the ground‐water is not confined under pressure. If the ground‐water is under artesian pressure, the cone of depression is a depression in the piezometric surface. If the cones of depression of two or more wells ending in the same formation overlap, interference of the wells occurs. In this case (the combined yield of the wells when pumped simultaneously will be less than the sum of the individual yields if the wells are pumped separately. In choosing the proper spacing of wells from the operator's point of view, it is important to know the lateral extent of the cones of depression of supply‐wells ending in a given formation. In many installations two or more wells are so closely spaced that their mutual interference is excessive.

New York