摘要:

The American Geophysical Union was established in 1919 as the American Committee of the International Union of Geodesy and Geophys cs, and its Executive Committee is the Committee on Geophysics of the National Research Council. The objects of the Union are to promote the study of problems concerned with the figure and physics of the Earth, to initiate and coordinate researches which depend upon international and national cooperation, and to provide for their scientific discussion and publication. In the accomplishment of these objects, the Union is divided into sections following the plan of organization of the International Union of Geodesy and Geophysics. There are now seven sections, namely, (a) Geodesy, (b) Seismology, (c) Meteorology, (d) Terrestrial Magnetism and Electricity, (e) Oceanography, (f) Volcanology, and (g) Hydrology. A Section of Geophysical Chemistry was discontinued May 31, 1924, as the International Union had failed to provide such a Section; the Section of Hydrology was established November 15, 1930—matters pertaining to scientific hydrology referred to the American Geophysical Union had been previously looked after by special committees on Hydrolog

ISSN:0002-8606    

DOI:10.1029/TR018i001p00003

年代:1937

数据来源: WILEY

摘要:

The minutes of the seventeenth annual meeting held May 1, 1936, were mimeographed and distributed to all members of the Union, to authors of papers presented at the meeting, and to officers of the International Union of Geodesy and Geophysics. No comments have been received suggesting any changes or corrections. A report of the seventeenth annual meeting, prepared by the General Secretary, was published inScienceof July 17, 1936.Since May 1, 1936, the Union has lost by death five members: E. E. Haslam, May 16, 1936, affiliated with the Section of Hydrology: C. F. Talman, July 24, 1936, affiliated with the Section of Meteorology; Henry M. Eakin, October 20, 1936, affiliated with the Section of Hydrology; Montrose W. Hayes, November 16, 1936, affiliated with the Section of Hydrology; D. L. Yarnell, March 9, 1937, affiliated with the sections of Meteorology and Hydrology. The General Secretary, on behalf of the Union, has expressed deep sympathy to each of the bereaved families.

ISSN:0002-8606    

DOI:10.1029/TR018i001p00008

年代:1937

数据来源: WILEY

摘要:

Time‐Signal Service(H. E. McComb, Chairman)—The Committee reported that a large number of users of United States Navy Department time‐signals in the fields of applied geophysics, geodesy, and seismology have supplied information relative to the extent of the use of these signals. The general character and number of these communications prove that the time‐signals are used in a wide variety of scientific investigations. The Committee will supply detailed information on specific signals in its final report to the Union. Several users have reported serious difficulties in the reception of the 9425‐kilocycle signal due to interference from foreign stations. Others have suggested the desirability of having additional signals on some of the standard frequencies now on the

ISSN:0002-8606    

DOI:10.1029/TR018i001p00010

年代:1937

数据来源: WILEY

摘要:

During the past year the principal collective activity of your Committee has been concentrated on completing the plans and the execution of the gravimetric and submarine topographic expedition to the West Indies. Your Chairman, together with Dr. Maurice Ewing and Dr. H. K. Hess, served as a subcommittee with Captain L.R. Leahy, Hydrographer of the United States Navy. Dr. Ewing was appointed chief scientist of the expedition, and was assisted by Lt. A. J. Hoskinson of the United States Coast and Geodetic Survey and Dr. Hess. Relatively late in the plans, it was decided to attempt to change the method of timing the pendulums. This would have proved a somewhat dangerous decision had it not been for the fundamental cooperation of the Bell Telephone Laboratories of New York, which, through its President, Dr. F. B. Jewett, and Mr. W. A. Marrison, provided a crystal chronometer, which was adapted to the Vening Meinesz apparatus. The Committee is deeply indebted to Mr. Marrison for this great improvement in the determination of gravity on land, as well as at sea.

ISSN:0002-8606    

DOI:10.1029/TR018i001p00013

年代:1937

数据来源: WILEY

摘要:

Somewhat over two years ago this Committee began work by undertaking an informal census and review of geophysical‐geological studies which were already in progress and which were of such a sort as to be naturally contributory to the objectives which the Committee was created to promote. As this survey progressed, the Committee also began the formulation of an informal but comprehensive statement of objectives—a copy of which was recently transmitted to the National Research Council's Committee on Borderland Fields through Professor Gutenberg. Because of the near‐completion of its general survey and planning activities, the Committee feels that its report this year should consist of a brief statement summarizing what it has accomplished to date, the work it now has in progress, and the activities which it contemplates or recommends for the immediate f

ISSN:0002-8606    

DOI:10.1029/TR018i001p00017

年代:1937

数据来源: WILEY

摘要:

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 Provinc

ISSN:0002-8606    

DOI:10.1029/TR018i001p00021

年代:1937

数据来源: WILEY

摘要:

It may be said at once that, in the strictest interpretation of the title, this paper does not belong in this symposium, for it is one of the fundamental theorems of gravitational attraction that the same external gravity‐field may be produced by any number of different distributions of internal mass. However, the external gravity‐field may be incompatible with a proposed internal distribution; furthermore, by applying our other knowledge In a common‐sense way we may from a knowledge of the external field perhaps come close to the actual internal distribution of de

ISSN:0002-8606    

DOI:10.1029/TR018i001p00033

年代:1937

数据来源: WILEY

摘要:

No one any longer doubts that earthquakes occur at depths of several hundred kilometers. There is not the same unanimity in regard to the absolute depth of focus of these earthquakes, the relative merits of methods for measuring the depth, the character, and distribution of plutonic earthquakes; and especially is there disagreement as to their causes and mechanism and as to their geological implications.Several methods have been suggested for the measurement of depth of focus. Most of these are relative methods. Turner based his estimate of the relative depth of focus on the degree of earliness in the arrival time of longitudinal waves at the antipodes in the case of deep shocks as compared with normal earthquakes. Stechschulte took as his criterion the interval between the arrival of the direct longitudinal wave and that of the Walker reflection at the distance at which this interval reached its maximum. Scrase used Knott's calculations to determine the depth of focus from the departure of the travel‐time curves for deep earthquakes from those of normal earthquakes. Wadati has suggested a number of methods: First, the spacing of the isochrones or lines of simultaneous arrival; second, the time‐Intercept of the graph of the interval between the arrival of the longitudinal and that of the transverse waves against the absolute arrival time of the longitudinal waves; third, he used tables of calculated travel‐times from deep foci based on those of shallow earthquakes, each set of tables corresponding to a given depth of focus. Miyamoto determined the depth of focus by comparing the travel‐times of longitudinal and transverse waves reflected from the core of the Earth with those for normal earthquakes. Serlage uses the interval between the arrival of the direct longitudinal wave and that of the Walker reflection for direct calculation of th

ISSN:0002-8606    

DOI:10.1029/TR018i001p00041

年代:1937

数据来源: WILEY

摘要:

Those who have attempted to picture the Earth's interior seem to have paid little or no attention to the inferences which may be drawn from terrestrial‐magnetic phenomena. Yet, no conception of the physical state of the Earth's interior can be complete and correct which fails to account for the facts of its magnetic condition. Furthermore, the study of terrestrial magnetism supplies information regarding the Earth's interior which is not revealed by any of the other geophysical science

ISSN:0002-8606    

DOI:10.1029/TR018i001p00043

年代:1937

数据来源: WILEY

摘要:

The “extreme” conditions of the title are conditions of stress attainable in the laboratory; the temperatures involved do not usually reach higher than 200° C. A number of experiments have been made in which shearing stresses sufficient to produce plastic flow have been applied at various pressures up to 50,000 kg/cm2. The magnitude of the shearing distortion produced in these tests is greater than that attained under ordinary conditions, the displacement in shear of one row of atoms tangential to the next row being of the order of tens of thousands. Furthermore, the plastic strength, or the force required to produce plastic flow, is usually many fold greater at 50,000 than at atmospheric pressure. This means that at 50,000 it is possible to study the effect of much greater shearing stresses than are realizable under ordinary condit

ISSN:0002-8606    

DOI:10.1029/TR018i001p00050

年代:1937

数据来源: WILEY