bluuebunny/crossref_metadata_2025 huggingface dataset:
NOTE ON REFLECTIONS FROM STEEPLY DIPPING BEDS
Authors: Heiland C. A.
Published: October 2002

A brief report is given of some experimental work on known geologic conditions conducted by the Pionier Company in southeastern Poland. This is a region of steep dips, severe folding, overthrusts, and step‐faulting. The geologic conditions are first described, and this is followed by a discussion of the mathematical and physical aspects of the problem. It is pointed out that the problem is essentially one of three dimensions. Its solution ordinarily demands that the azimuth of shooting, in relation to strike, and the travel time relations at right angles to the strike, be known. But for the steep dips encountered in mountainous country, this is not always possible. Then the Time Gradient is a convenient criterion of the dip component in the direction of shooting. The problem is reduced to one of finding the time gradient in the direction of maximum dip. Curves of the time gradients are given for horizontal and for dipping beds. The method is applied to selected records and found to work well. The conclusion is reached that, where shots in different azimuths are impossible, there is an optimum azimuth, just as there is an optimum spread; but it may take much experimentation to determine where this azimuth is.
THE GROWTH OF COMPANY OWNED OPERATIONS IN GULF COAST GEOPHYSICAL PROSPECTING SINCE JULY 1930
Authors: Rosaire E. E. , Ransone K.
Published: October 2002

Graphical data are presented for the refraction seismograph, torsion balance, and reflection seismograph in the Gulf Coast over the period July 1930 to February 1936. For comparison, the variations in the price of 30° Baumé crude oil at Houston are presented for the same period. The results indicate that: (1) The refraction seismograph was discarded before the 1931 minimum in the price of oil. (2) During this 1931 minimum, exploration of any kind was practically non‐existent. (3) The 1933 minimum, on the contrary, seems to have effected contract operations more than company owned operations. (4) Company owned torsion balance operations seem to have reached a saturation point while contract torsion balance operations are rapidly decreasing from their 1934 peak. (5) Company owned reflection operations have shown a steady increase of ten crews per year while contract operations have shown a very irregular increase, averaging six crews per year, since 1932. (6) New contract reflection companies have appeared since 1930 at the rate of three per year. (7) The peak of contract reflection operations will probably be reached in 1937 or 1938, after which these operations will disappear in the same fashion as did the contract torsion balance operations.
EARLY REFLECTION SEISMOGRAPH EXPLORATION IN CALIFORNIA
Authors: Salvatori Henry
Published: October 2002

The first major attempt to employ the reflection method in California was made in 1931. The first results were disappointing, but by the early part of 1932 a prospect near Merced was successfully mapped. The correlation method was found to have limited applicability and the dip method was generally adopted. Most of the early work was performed with wide spacing of stations and lines since very close control was not considered necessary to discover the larger structural features which were then of greatest interest. As a result of this early reflection work several important oil fields were discovered among which are the Wilmington and Rio Bravo fields. A brief history of the discovery of these two fields is given and the seismic maps are compared with the later geologic maps compiled from well data.
GRAVITY AND MAGNETIC INVESTIGATIONS AT THE GRAND SALINE SALT DOME, VAN ZANDT CO., TEXAS
Authors: Peters Jack W. , Dugan Albert F.
Published: October 2002

During May, 1944, detailed gravity and magnetic surveys were made at the Grand Saline Salt Dome to secure additional information on the physical properties of this typical East Texas salt dome. The results of the surface gravity and magnetic surveys, and the subsurface gravity survey in the Morton Salt Mine are illustrated and discussed. Densities and the available subsurface data were compiled and were utilized in a quantitative evaluation of the observed gravity data. The theoretical mass distribution which was determined by this quantitative evaluation is not intended to represent the unique solution of the geophysical and geological data; instead, it is offered as a possible solution based on relatively simple assumptions.
THE NARROW‐BAND RESISTANCE‐COUPLED AMPLIFIER
Authors: Cowles Laurence G.
Published: October 2002

A method for the design of the amplifier coupling circuit is presented in a form permitting the selection of circuit constants directly from a specified band width, peak frequency, and peak frequency coupling loss. The design procedure is illustrated by several practical examples; the limitations of the narrow‐band amplifier are discussed.
EFFECT OF RAY CURVATURE UPON SEISMIC INTERPRETATIONS
Authors: Stulken E. J.
Published: October 2002

With theory of seismic paths fairly well established and with errors due to neglect of ray curvature considered in general terms or isolated examples by several authors, there remains a need for extended calculations measuring the effect of curvature. For a specific family of velocity functions inaccuracies of velocity computations based on straight path assumptions are illustrated graphically. Discrepancies traceable to use of straight line methods of depth, dip offset determination are likewise described. Certain fallacies attending the application of simple curved path procedure to seismic prospecting are considered briefly so that a reasonably fair evaluation of net importance of the ray curvature problem may be attempted.
“REFRACTION WAVES REFLECTED FROM A FAULT ZONE”
Authors: Robinson W. B.
Published: October 2002

Many records of a reflection project in Webb County, Texas, displayed events showing excessive step‐out times. These events are treated as refraction waves following a near‐surface marker horizon, and their origin is shown to be associated with faulting which was mapped by the ordinary reflections on the records. Possible confusion that may arise from failing to recognize these anomalous events is discussed as well as the possibility of using the phenomenon to map faults.
ON WELL VELOCITY DATA AND THEIR APPLICATION TO REFLECTION SHOOTING
Authors: Narvarte P. E.
Published: October 2002

Current methods of computing seismic reflection data employing the integration of the actual velocity‐depth (or velocity‐time) relation in the velocity column are confronted with difficulties and limitations because they neglect the stratigraphic effect on the velocity distribution. A method is proposed where the measured incremental time‐depth relation, ΔZ/ΔT, to each of a number of stratigraphic markers may be combined into one generalized depth or time function satisfying well velocity data from a number of wells. The proposed method employs the integration of this slope relation and is used in conjunction with regional correction contour maps. Because this relation results from the combined load and stratigraphic effects together with the geological behavior of the section, this method offers distinct advantages both in accuracy and applicability. Advantages and limitations in the application of this method are discussed.
AIRPLANE NOISE INTERFERENCE WITH SEISMIC PROSPECTING
Authors: Kendall J. M.
Published: October 2002

The low frequency sound produced by airplanes is briefly investigated, and its propagation through the atmosphere is considered. Data on a cargo type airplane are presented. Rough calculations to determine the response of geophones to this sound field indicate that one airplane can blanket an area of several hundred square miles. Measures suggested for minimizing the interference are discussed.
SEISMOGRAPH EVIDENCE ON DEPTH OF SALT COLUMN, MOSS BLUFF DOME, TEXAS
Authors: Hoylman H. Wayne
Published: October 2002

Clear reflections at times of approximately 2.3 and 4.4 seconds were obtained consistently on a series of records shot directly over the shallow cap rock of the Moss Bluff dome. The earlier reflection can be interpreted as from the base of the salt column, at a depth of around 16,000 feet, or from a discontinuity within the salt column. The later reflection can be interpreted as from the base of the salt column at around 36,000 feet, from the basement complex at around 26,000 feet, or as a multiple of the reflection from the base of the salt column at around 16,000 feet. Reasons are given for preferring the multiple reflection interpretation.
DISTURBING FACTORS IN GEOCHEMICAL PROSPECTING
Authors: Pirson Sylvain J.
Published: October 2002

A review of the results of over 3,000 measurements of soil ethane emanation rate made over the past five years has revealed a number of conclusions which have an important bearing upon the validity of geochemical methods of prospecting for oil and gas fields. A number of factors have been found to be highly disturbing, namely: earth topography, ground water percolation and seepage, barometric pressure variations, etc. These effects result in fluctuations of the rate of escape of hydrocarbons accompanied by horizontal shifts of leakage which give rise to the creation of artificial leakage highs altogether meaningless from the point of view of oil and gas accumulation at depth. Certain qualitative rules of interpretation have been established which permit weeding out the meaningless anomalies provided sufficient information is at hand on the topography and watertable movement. A further observation has been made indicating that the artificial anomalies are often of greater magnitude than the significant measurements. Hence the problems, so common in other geophysical methods, of making important reductions on the observed figures are imperiously facing the exploration geochemist if he is to develop a valuable prospecting tool. A serious attempt is presently made to solve this problem.
FOREIGN GEOPHYSICAL ACTIVITIES IN 1945
Authors: Heroy William B.
Published: October 2002

The Petroleum Administration for War was concerned with geophysical operations in foreign countries because such work had a direct bearing upon the possibility of discovering new fields and finding new reserves of petroleum. At the beginning of 1945 no one could confidently predict the time when war requirements for petroleum would cease and it was necessary to look ahead for an indefinite period in planning for future oil production. New fields in accessible locations were an important element in the future petroleum supply situation.
THE INTERPRETATION OF WELL SHOT DATA. III.
Authors: Dix C. Hewitt
Published: October 2002

The present paper is an attempt to take account of the lateral variations in velocity that are found usually by shooting a number of wells. More particularly, we show how, by tilting the linear distribution of velocity with depth in the proper way, we can tie the various wells together, accounting approximately (and usually to a sufficient extent) for all lateral variations of velocity. The problem arising when three wells are shot is discussed in some detail. It is also shown that the lateral change of velocity can be determined approximately by shooting one well alone, and an approximate method of determining the tilt of the datum plane is discussed.
GEOPHYSICAL HISTORY OF TYPICAL MISSISSIPPI PIERCEMENT SALT DOMES
Authors: Nettleton L. L.
Published: October 2002

Maps and cross sections are given, showing the development of geophysical and geological knowledge of the New Home and D’Lo domes. Both are shallow, piercement domes in the northern part of the Mississippi salt dome basin. Both were first indicated by gravity surveys, the shallow cap‐rock checked by refraction seismograph surveys, cap‐rock depths checked by drilling and further seismograph work and drilling then carried out to determine the position of the salt and the attitude of the sediments. The successive items of geophysical work and test drilling have led to a consistent and orderly development of information about these domes. An additional note is included, with three pairs of gravity maps, showing how strong and definite, but very local, gravity expressions of shallow domes may be missed by reconnaissance surveys.
GEOPHYSICAL HISTORY OF THE GUTHRIE FIELD, LOGAN COUNTY, OKLAHOMA
Authors: Swan B. G. , Boyd W. B.
Published: October 2002

The geophysical history of the Guthrie Oil Field, as presented in this paper, consists of a reflection seismograph survey in early 1938; a re‐interpretation of these data in 1941; and a detailed reflection seismograph survey in 1941, after the discovery of oil, to outline dimensions of the structure more definitely. Early concern over the fact that Viola reflection times failed to show east closure on the structure was later dispelled when drilling developments showed that closure actually was not present on horizons above the Second Wilcox sand.
GEOPHYSICAL HISTORY OF THE WASCO OIL FIELD, KERN COUNTY, CALIFORNIA
Authors: Erickson E. L.
Published: October 2002

The reflection seismograph surveys which led to the discovery of Wasco oil field were started in 1934. Some additional work was done to outline the structure in 1935. Subsequent to discovery in 1938 a detailed reflection seismograph survey was made for the purposes of aiding development and securing type seismograph data.
GEOPHYSICAL HISTORY OF THE VILLE PLATTE OIL FIELD, EVANGELINE PARISH, LOUISIANA
Authors: Warren Paul R.
Published: October 2002

The brief pre‐discovery geophysical activity by Continental Oil Company in the area of the Ville Platte Field consumed twenty‐five working days and consisted of a reflection seismograph survey employing symmetrical setups far removed from the shotpoints. After discovery a gravity meter survey revealed a gravity minimum almost coinciding with the seismograph structure and the productive area.
GEOPHYSICAL EXPLORATION AND DISCOVERY OF THE BUDAFAPUSZTA (LISPE) OIL FIELD IN HUNGARY
Authors: Skeels D. C. , Vajk Raoul
Published: October 2002

Interest was first attracted to the Budafapuszta area by its geographical position on the eastward projection of a known surface anticline, which had produced small quantities of oil at Peklenicza and Szelnicza. A test was located in 1920 on a small surface feature, and completed in 1923 as a dry hole. In 1934 a torsion balance survey was made by Eurogasco, a subsidiary of the Standard Oil Co. (N. J.) which indicated a dome with its crest 1500 m. north of the dry hole. A reflection survey verified the presence of the structure. The discovery well was located by the torsion balance data, and completed as a producer in 1937. A gravity meter survey made after the first two producers had been drilled, gave further information on the structure and assisted in the development of the field. This exploration history shows that a properly made torsion balance survey may be very efficient and economical even in hilly country. A geological map of part of the Szelnicza‐Peklenicza anticline, a topographical map, torsion balance, seismograph and gravity meter maps, a seismograph cross section and a subsurface contour map of the Budafapuszta structure are submitted.
GEOPHYSICAL CONTRIBUTIONS TO VIBRATION MEASUREMENTS AND MICRO‐CHEMISTRY
Authors: Hawley P. F.
Published: October 2002

This paper gives a brief account of the development, during the war emergency, of equipment made especially for the measurement of vibration and strain in airplane structures in flight. Experience in the design and manufacture of seismograph equipment made rapid development possible. A mass spectrometer is also described. This instrument was built originally for analysis of gas samples in connection with geochemical prospecting, was then adapted for rapid analysis of complex hydrocarbon mixtures and has found application particularly in control of refinery processes.
DISCUSSIONS AND COMMUNICATIONS: INTERNATIONAL GEOLOGICAL CONGRESS: XVIII SESSION, LONDON, 1948
Authors:   General Secretaries, XVIII Session International Geological Congress
Published: October 2002

The XVII.I Session of the International Geological Congress, originally planned for 1940 and postponed on the outbreak of the war, is to be held in Great Britain in 1948, on the invitation of the Geological Society of London.
A STUDY OF SEISMIC CHARACTER AND ENERGY RETURN FROM SHOOTING HIGH‐ AND LOW‐VELOCITY EXPLOSIVES
Authors: Dobyns D. R.
Published: October 2002

This paper is a report of an investigation of the possibilities of changing the character of reflection records by shooting explosives which vary in detonation velocity from 5000 to 21,000 ft/sec; and also to determine what energy return would result from shooting such various explosives in refraction work. Magnolia Petroleum Company under my direction carried out these investigations on crews in Florida, Mississippi and Texas. A discussion of results and presentation of records will be made.
THE EXISTENCE OF MULTIPLE REFLECTIONS
Authors: Dix C. Hewitt
Published: October 2002

On several occasions during the past several years, various geophysicists have expressed, in private discussion, doubt regarding the existence of multiple reflections or at least their recordability over background noise. Hence the following comments.
MAGNETIC PROPERTIES OF “GRANITE” WASH AND UNWEATHERED “GRANITE”
Authors: Taylor Garvin L. , Reno Duane H.
Published: October 2002

Routine measurements of the magnetic properties of various geological formations show that “granite” wash, although having an appearance in well samples very similar to that of unweathered “granite,” has very different magnetic properties. Magnetic logs of wells located in Southwestern Oklahoma, Texas Panhandle and Eastern New Mexico show a large increase in the magnetic susceptibility when unweathered “granite” is encountered. Samples of “granite” and “granite” wash collected from the Wichita Mountains in Oklahoma show a marked decrease in magnetic susceptibility during the formation of “granite” wash from unweathered “granite.” It is concluded that magnetic logs made by testing well samples will be of assistance in differentiating “granite” wash from the underlying unweathered “granite.” Tests of samples of unweathered “granite” upon exposure to weather show a measurable to marked decay of susceptibility and remanent magnetism in the relatively short time of a few years.
THE DISCOVERY HISTORY OF THE UNIVERSITY OIL FIELD, EAST BATON ROUGE PARISH, LOUISIANA
Authors: Atwater Gordon
Published: October 2002

The localized occurrence of salt water in shallow wells on and near the Louisiana State University campus, in addition to shells collected during the drilling of these wells, attracted the attention of geologists to this area prior to 1926. A torsion balance survey in 1931 was followed by a dry hole drilled in 1933 southeast of the present field. Three separate reflection seismograph surveys during the period of 1934 to 1937, on each one of which a well was drilled without establishing production, were made on the University structure prior to discovery in 1938. The location based on the first reflection seismograph survey should have resulted in the discovery of both the shallow and deep production, and the discovery location was finally made because of the oil and gas shows encountered in this abandoned test. After discovery, an additional reflection survey was made to detail the structure as an aid in development.
GEOPHYSICAL EXPLORATION BY TELLURIC CURRENTS, WITH SPECIAL REFERENCE TO A SURVEY OF THE HAYNESVILLE SALT DOME, WOOD COUNTY, TEXAS
Authors: Boissonnas Eric , Leonardon Eugene G.
Published: October 2002

The fact that natural currents flow through the ground has been known for quite a long time. Some of these currents are local in character; some involve the whole of the earth’s surface. These latter currents are called telluric currents. Their behavior and properties are outlined in general, and their usefulness for the practical purpose of geophysical exploration is discussed at length. In conclusion, an example of an actual survey by telluric currents on the Haynesville Salt Dome (Texas) is given, which illustrates the quality of the results which can be obtained in similar cases.
LOW‐SPEED LAYER IN WATER‐COVERED AREAS
Authors: Press Frank , Ewing Maurice
Published: October 2002

In many water‐covered areas it has been reported that the speed of sound in the topmost layers of the bottom is less than that in water. Several methods of investigating such layers are discussed. The normal‐mode theory offers the best method of detecting and investigating a low‐speed layer covered by water.
MICROCARDS, A NEW METHOD OF PUBLICATION
Authors: Dix C. Hewitt
Published: October 2002

The recently introduced system of microcards promises to fill such an important combination of vital needs in the field of publication as to appear to be potentially revolutionary. In view of this development and its consequent advantages to geophysicists and geologists, it has been thought timely to present in Geophysics a description of the microcard method with some comments on its possibilities.
GEOPHYSICAL ACTIVITY IN 1949
Authors: Eckhardt E. A.
Published: October 2002

The trend of geophysical activity during 1949 was away from the United States; whereas, seismograph activity in the United States was down 1.43 per cent from the preceding year, that elsewhere was up 28.85 per cent. Gravity operations in the United States in 1949 were down 31.29 per cent as compared to 1948. Elsewhere the decrease was 14.17 per cent. This report is designed to give a composite picture of the geophysical operations of last year with regard to their magnitude and geographic distribution.
THE FORT COBB ANTICLINE A Geophysical Case History
Authors: Campbell Francis F.
Published: October 2002

The Fort Cobb anticline is in T‐8‐N, R‐12‐W, Caddo County, Oklahoma. Its history is one of geophysical success and commercial failure. Amerada Petroleum Corporation found seismic evidence of a large closed structure and drilled a 10,000 foot dry hole on top of it. Then The Superior Oil Company shot the area and drilled two more tests. The first Superior test was drilled to 17,800 feet and was the deepest test in the world at the time. The presentation of data includes reproductions of seismic records, cross‐sections, and structure maps on three horizons.
THE TELLURIC METHOD OF PROSPECTING AND ITS LIMITATIONS UNDER CERTAIN GEOLOGIC CONDITIONS
Authors: Tuman V. S.
Published: October 2002

This paper is in four parts: Part one, deals with general considerations of geophysical methods. Part two briefly mentions the properties of the telluric field, and the telluric method. In part three, some simple problems are discussed, and as a result of the discussion, two factors are introduced: (A) The tectonic factor, ϕ which is a function of the geology of the area. It could neither be measured, nor easily calculated; but only estimated roughly from the shape and the orientation of the ellipses. (B) The distorting factor Ψ which is a function of the physical properties of the beds. Its value could only be calculated, when the thicknesses of the beds, and their resistivity are known at the point of the measurements. In part four, it is concluded, that these factors set a limit in correlating the surface measurements to the actual shape and the size of the structure, and thus a limit to the interpretation of the results of a telluric survey.
INDEX OF WELLS SHOT FOR VELOCITY
Authors: Swan B. G.
Published: October 2002

Information is listed on 498 well velocity surveys not previously reported in the three earlier publishings of the Index. Most of these are new surveys shot since the fall of 1948. Corrections and additional information on surveys previously listed are also given.
GEOLOGY AND GEOPHYSICS OF THE NORTH SNYDER AREA, SCURRY COUNTY, TEXAS
Authors: Clayton Neal
Published: October 2002

Discovery of the North Snyder reef in November, 1948 by the Standard of Texas focused the attention of the oil industry on this part of West Texas and presented the geophysicist with the problem of how to locate other reefs of this type. The North Snyder reef is unique in that reflected energy is obtained from the reef‐shale contact in some parts of the field. Magnetic, gravimetric and seismic data are presented to show some of the effects to be expected from a reef of this type. A number of electric log correlations are included in order to illustrate the geology of the field. From the electric logs it appears that the “draping” effect is small above the thick Pennsylvanian shale section which compensates for the reef mass. Contour maps for the base of the Coleman Junction limestone and the top of the Canyon reef are presented.
DISPERSION IN SEISMIC SURFACE WAVES
Authors: Dobrin Milton B.
Published: October 2002

A non‐mathematical summary is presented of the published theories and observations on dispersion, i.e., variation of velocity with frequency, in surface waves from earthquakes and in waterborne waves from shallow‐water explosions. Two further instances are cited in which dispersion theory has been used in analyzing seismic data. In the seismic refraction survey of Bikini Atoll, information on the first 400 feet of sediments below the lagoon bottom could not be obtained from ground wave first arrival times because shot‐detector distances were too great. Dispersion in the water waves, however, gave data on speed variations in the bottom sediments which made possible inferences on the recent geological history of the atoll. Recent systematic observations on ground roll from explosions in shot holes have shown dispersion in the surface waves which is similar in many ways to that observed in Rayleigh waves from distant earthquakes. Classical wave theory attributes Rayleigh wave dispersion to the modification of the waves by a surface layer. In the case of earthquakes, this layer is the earth’s crust. In the case of waves from shot‐holes, it is the low‐speed weathered zone. A comparison of observed ground roll dispersion with theory shows qualitative agreement, but it brings out discrepancies attributable to the fact that neither the theory for liquids nor for conventional solids applies exactly to unconsolidated near‐surface rocks. Additional experimental and theoretical study of this type of surface wave dispersion may provide useful information on the properties of the surface zone and add to our knowledge of the mechanism by which ground roll is generated in seismic shooting.
GEOPHYSICAL FRONTIERS
Authors: Wagoner George E.
Published: October 2002

In the years 1920 to 1940 there existed in the United States a vast frontier of undeveloped area to challenge geophysics. A great unexplored reserve of oil traps awaited the enterprising geophysicists who first brought their scientific devices to these strange lands. Through those early years, there was always new acreage for everybody interested; it was only necessary to stay away from, or keep ahead of, the competition. It was a lush period of easy, ready exploration. The geophysical frontier was the virgin area.
MULTIPLE REFLECTIONS ON THE EDWARDS PLATEAU
Authors: Poulter Thos. C. , Lombardi Leonard V.
Published: October 2002

Seismic records obtained at the same point with hole and surface charges are compared. Evidence is presented that multiple reflections from within the Edwards limestone are sufficiently prominent on the hole shot records to mask and obscure primary reflections. It is postulated that the large number of these multiples is attributable to the great amount of high frequency energy generated in the competent Edwards limestone by a hole shot. The relative lack of multiple reflections on the Poulter Method records is believed to be due largely to the fact that essentially all of the energy entering the ground is of low frequency in the part of the spectrum available for deep reflections. This nullifies the apparent high frequency selectivity effect of the Edwards limestone.
THE INTERPRETATION OF ELECTROMAGNETIC REFLECTION DATA IN GEOPHYSICAL EXPLORATION—PART I, GENERAL THEORY
Authors: Yost W. Jacque
Published: October 2002

It is shown that any variable current method of electrical exploration must be interpreted in terms of a semi‐infinite conducting medium underlying a semi‐infinite insulator. The complete theoretical treatment for a homogeneous conductor is outlined, and the details of the solution for low frequencies are presented. These indicate that the measured field intensities are not in‐phase with the exciting current as has previously been assumed. These out‐of‐phase components from a homogeneous earth complicate the desired interpretation in terms of resistivity discontinuities at depth. The results of this paper provide a means of suitably correcting for this factor. Secondly, the insulating (air) region is shown to have an influence on the electromagnetic fields within the conductor. Thus, when considering the image approximation, the images are influenced by the air region and cannot be assumed to behave as they would in an infinite conductor. The lack of validity of this earlier assumption is demonstrated and suitable correction factors are derived. Specific results for the two cases of most practical interest are presented in graphical form. These are compared with experimental data obtained from a laboratory scaled model composed of metallic plates.
SUBSURFACE GRAVITY MEASUREMENTS
Authors: Rogers George R.
Published: October 2002

Gravity data were obtained at approximately 100-foot intervals in a vertical mine shaft 2,916 feet deep. The shaft passed through a region of high positive density contrast, and a local anomaly was observed of plus 14.0 gravity units to minus 17.9 gravity units. Calculations for Bouguer densities were carried out with the gravity measurements. A theoretical sphere that closely approximates the observed data and known conditions is derived from the gravity data.
GEOPHYSICAL ACTIVITY IN 1951
Authors: Eckhardt E. A.
Published: October 2002

Unprecedented is the word which most aptly describes the expansion of geophysical activity which took place during 1951. The seismograph work done everywhere by the oil industry during the year required the full time services of 791 crews, an increase of 134 crews or 20.4 percent over 1950. Gravity work was also done in substantially greater volume during 1951, requiring the full time services of 123 crews, an increase of 13 or approximately 12.2 percent over 1950.
GEOPHYSICAL METHODS ADAPTED TO HIGHWAY ENGINEERING PROBLEMS
Authors: Moore R. Woodward
Published: October 2002

Of the several geophysical methods used in exploration for oil and useful ore bodies, the earth‐resistivity and seismic‐refraction tests have been found to be the most adaptable to the shallow tests generally required in highway construction work. Of these, the earth‐resistivity test is the faster and has a wider range of application to highway problems than does the seismic test. Use of both methods of tests in subsurface explorations for engineering structures is expanding. The paper cites a growing need for a more thorough subsurface investigation of all engineering structure sites and gives examples of field data obtained by the Bureau of Public Roads when making preliminary geophysical surveys of proposed highway locations or structure sites. The economic aspects and the advantages and limitations of the two methods of test are discussed with particular reference to their application to highway engineering problems.
AN ANALYSIS OF AIRBORNE SURVEYING FOR SURFACE RADIOACTIVITY
Authors: Cook John C.
Published: October 2002

Quantitative estimates of the gamma radiation field intensities expected to be encountered in flight over various geologic bodies are presented. Scattering effects are included in the calculations, but several simplifying assumptions were necessary, such as assigning equal energies to all photons. Results are compared with geiger counter measurements of three kinds: near a small natural carnotite deposit, near a tenth‐curie of radium, and soundings made over normal terrain at various times. It appears that anomalies from most outcrops of radioactive ores will exceed the normal fluctuations of background radiation due to topography, variations of composition of the surface, etc., only at flying altitudes of less than about 35 feet. However, such anomalies can probably be detected under favorable conditions by their characteristically pointed shape, allowing flight at higher elevations. Requirements on flight plan and instrumentation are discussed.
VARIATION OF ELASTIC WAVE VELOCITY WITH SATURATION IN SANDSTONE
Authors: Hughes D. S. , Kelly J. L.
Published: October 2002

The velocity of dilatational waves in four sandstones has been measured as a function of pressure in the range 50 to 1000 bars at room temperature and at 100°C. At least two cores from each sample were run, one dry and one saturated with water. In addition two cores from one sample were run at several partial saturations. The porosities of the samples varied from about 8 to 20 percent. The effect of water content is dependent on pressure. At low pressures (50 bars) the velocity rises sharply at small saturations (0–10 percent), remains constant with saturation 10 to 90 percent and then decreases as the saturation approaches 100 percent. At 50 bars the velocity at 100 percent saturation is generally higher than that at 00 percent saturation. Even for the one exception an extrapolation would indicate this to be true at atmospheric pressure. As the pressure is increased the rise at low saturations decreases; at 500 bars it disappears. The velocity is almost constant with saturation until about 90 percent saturation is reached. It then decreases rapidly as 100 percent saturation is approached. A qualitative explanation of these results is given.
GEOPHYSICAL EXPLORATION IN THE SAN JUAN BASIN
Authors: Clayton Neal
Published: October 2002

Geophysical surveying in the San Juan Basin involves a number of problems peculiar to the area. Magnetometer and gravity meter surveys are complicated by topography and the presence of Tertiary intrusives. Scarcity of water is a major problem for seismic crews. Some arrangements must be made for housing crew employees. Velocity and subsurface control are extremely limited.
ORE BODY SIZE DETERMINATION IN ELECTRICAL PROSPECTING
Authors: Seigel Harold O.
Published: October 2002

A method of determination of the size of ore body associated with a mineralized intersection is presented which utilizes the primary voltage disturbance created by the body and the variation of the disturbance with electrode spacing. The form of the disturbance function is compared with theoretical curves based on the oblate spheroid.
PETROLEUM EXPLORATION ON OUR PUBLIC LANDS
Authors: Killough John R.
Published: October 2002

Exploration for oil and gas has soared to an all time maximum, and it will continue to increase. In eleven western states such exploration will be predominantly on our public lands. These lands are managed to (1) conserve and perpetuate natural resources, (2) give greatest good to the greatest number, and (3) have the benefits exceed the cost. The conservation program of the Bureau of Land Management is engaged in the construction of soil and moisture conservation projects, range improvements, and revegetation. At the present time the Bureau is actively engaged in controlling the poisonous invader Halogeton, employing herbicides and reseeding. Seismic methods, as often employed, may be destructive to soil and vegetation or surface resources and therefore opposed to other activities and interests. Direct losses occur through improperly bulldozed trails and the use of stockwater reservoirs. Shot holes left unplugged are dangerous. The oil and gas industry must develop conservation policies within its own ranks. Roads may be properly constructed and damage repaired. The petroleum industry must decide by its own actions its future place on our public domain.
THE EFFECT OF PRESSURE ON THE REDUCTION OF PORE VOLUME OF CONSOLIDATED SANDSTONES
Authors: Hughes D. S. , Cooke C. E.
Published: October 2002

The changes in pore volume of jacketed dry sandstone samples have been measured under hydrostatic pressures over the range 50 to 1,000 bars (14,504 psi). The percent change in pore volume at each pressure and the pressure coefficient of change of pore volume have been computed. All measurements were made at room temperature. The total change in pore volume when the hydrostatic pressure was increased from 50 to 1,000 bars was found to be about 7.5 percent of the pore volume for a sample of Steven sandstone (porosity 18.5 percent) and approximately 3.0 percent of the pore volume for a sample of Berea sandstone (porosity 19.4 percent). The coefficient of change of pore volume with pressure is found to decrease rather rapidly with increasing pressure up to around 500 bars. Thus pressure changes applied to rock become much more important when the original geostatic load on the rock is small.
OIL AND GAS EXPLORATION IN ALABAMA, GEORGIA, AND FLORIDA
Authors: Baum Robert B.
Published: October 2002

The discovery of the Pollard oil field in southern Alabama early in 1952 sparked a campaign of leasing and exploration which spread quickly into Georgia and Florida. Three fields in southwestern Alabama and one in southern Florida account for all the oil production in the three states. Some aspects of the general geology and geophysics of the area, illustrated with maps, cross sections, and correlation charts, suggest the presence of geologic conditions favorable for the possible trapping and accumulation of oil and gas. Early seismograph exploration in much of the area was not effective, but in recent months the tempo of seismic activity has been accelerating, and improvements in instrumental and interpretive techniques are being achieved through current experimental work. The use of the various geophysical methods contributed to the discovery of the four oil fields located in the area. The structural traps indicated by the contour maps of the four fields are of the type sought by the reflection seismic method. Examples of representative reflection records indicate the presence of usable and correlatable seismic events. A seismic cross section prepared from data of this type shows the fault zone associated with the Pollard field. The existence of favorable geologic conditions in the southeastern states and the recent oil field successes at Pollard and South Carlton indicate the continuing of active development and exploration throughout the area.
OUR HUMAN ASSETS IN GEOPHYSICS
Authors: Johnson Curtis H.
Published: October 2002

The three societies represented here have a common purpose: oil‐finding. In the pursuit of this purpose they may achieve many other incidental goals; make many far‐reaching contributions to the broad fields of geology and geophysics, and even to the fields of physics and chemistry. But the prime purpose toward which the efforts of most of the members are directed is still oil‐finding. On that we shall be judged.
A SAFETY PROGRAM—MANAGEMENT’S RESPONSIBILITY
Authors: Westby G. H.
Published: October 2002

The extremely poor safety record of the contract geophysical industry should be corrected not only for the humanitarian and economic gains it would bring the individual company, but also for the improvement it would make in the industry’s public relations and ability to attract technically trained men. Management of the geophysical contracting companies should be cognizant of the importance of such a program and eager to participate in the S.E.G. safety program. Management of the oil companies, represented by those who are responsible for hiring contract geophysical companies, should help assure the success of this program and its related good consequences to the oil industry by demanding that geophysical contracting companies, in addition to meeting all their other requirements, have a safety program and cooperate with the S.E.G. in its safety program.
RADIATION FROM A CYLINDRICAL SOURCE OF FINITE LENGTH
Authors: Heelan Patrick Aidan
Published: October 2002

This paper presents the results of a theoretical study of radiation from a cylindrical source of finite length, the walls of which are subjected to symmetric lateral and tangential stresses. Three divergent wave systems are generated, P, SV, and SH, and their amplitudes are calculated in terms of the stresses operative on the walls of the “equivalent cavity.” The zonal distribution of amplitude in the three wave systems is calculated, and the total amount of energy in each is estimated. It is shown that under the action of a lateral pressure only, an SV wave of amplitude 1.6 times the maximum amplitude of the associated P‐wave is beamed from the source in directions making angles of 45° with the axis of the source.
GEOPHYSICAL ACTIVITY IN 1953
Authors: Hammer Sigmund
Published: October 2002

Geophysical activity in the search for oil in 1953 on a global scale maintained but probably did not exceed the record high established in 1952. Increased activity occurred in Mexico, in South America, and in Africa and the Far East. These increases offset small but definite declines in geophysical activity in the U. S. and in Canada.
MAPPING NEARLY VERTICAL DISCONTINUITIES BY EARTH RESISTIVITIES
Authors: Logn Ö.
Published: October 2002

Following a procedure similar to the method used by Stefanesco et al. (1930) in resistivity computations for a horizontally bedded earth, integral formulas are evaluated for the potential distribution around one current electrode placed in the neighbourhood of (a) one vertical plane of discontinuity and (b) two vertical planes of discontinuity. The integral formulas are shown to be identical to the series evaluated by Hedström (1932) using a Maxwell theory of images. The apparent resistivity in the one‐current‐electrode configuration is defined, and integral formulas are given for planes of discontinuity. Because the evaluation of apparent resistivity curves across a gangue of small thickness is troublesome by these formulas, approximation formulas for a thin vertical sheet are evaluated, these are found to be of sufficient accuracy in most cases met in the field. It is suggested that nearly vertical faults, rock boundaries, and breccias in many cases give geoelectrical anomalies which can be assumed to be caused by vertical planes of discontinuity. As an example, resistivity data are presented which were taken across a breccia in Meheia, near Kongsberg, Norway.
Discussion of a review by E. E. Rosaire (GEOPHYSICS, Vol. II, No. 1, January, 1937, pp. 63–67).
Authors: Barton Donald C.
Published: October 2002

Considerable space is spent by Rosaire in charging geologists with undue delay in recognizing the importance of faulting in the structure of the Mexia and Currie (not Conroe) oilfields.
EQUIVALENT ELECTRICAL NETWORKS OF SOME SEISMOGRAPHS
Authors: Scherbatskoy S. A. , Neufeld J.
Published: October 2002

The magnetic and electrostatic geophones are represented by means of “equivalent electrical circuits” which consist of linear networks, the characteristics of which are such as to give an external behaviour identical to that of a geophone. Various types of seismographs are considered from the standpoint of equivalent electrical networks and a few typical cases are treated quantitatively.
MODEL SEISMOLOGY—THE CRITICAL REFRACTION OF ELASTIC WAVES
Authors: O’Brien P. N. S.
Published: October 2002

Model experiments on the head wave are described. Quantitative data are obtained for three different pairs of media: light lubricating oil on top of a saturated solution of calcium chloride, water on top of wax, and water on top of concrete. Within the limits of experimental error these data agree with the theoretical prediction that the head wave should decay with distance as [Formula: see text] (Heelan, 1953).
VELOCITY ANISOTROPY IN STRATIFIED MEDIA
Authors: Uhrig L. F. , Van Melle F. A.
Published: October 2002

The phenomenon of velocity anisotropy in stratified rocks has been observed in surface outcrops by McCollum (1932), Weatherby (1934), Ricker (1953), White and Sengbush (1953), and their associates. In 1944, 1948, and 1953 Shell Oil Company measured oblique times from shots spaced at large distances from a well to a seismometer in the well and found evidence of velocity anisotropy. Cholet and Richards (1954) also observed this phenomenon in well‐velocity surveys at Berriane (North Sahara) An anisotropy factor A which is defined as the ratio of the velocity along the layers to the velocity perpendicular to the layers, has been computed from oblique‐time and well‐survey data. The factor A varies between 1.1 and 1.4 for the data collected in this report. At present, information on velocity anisotropy is limited and it is therefore suggested that oblique time measurements be made along with vertical velocity surveys whenever possible.
SIMULTANEOUS GAMMA RAY AND RESISTANCE LOGGING AS APPLIED TO URANIUM EXPLORATION
Authors: Broding R. A. , Rummerfield Ben F.
Published: October 2002

The transferring of petroleum exploration thinking and methods to uranium exploration has greatly facilitated the search for radioactive ores. Radioactivity and resistance logs obviate the need and expense of taking continuous cores to locate mineralized zones in shallow core holes. Specialized instrumentation, field equipment, and interpretive techniques are required in applying these logging methods to uranium exploration. Radiometric analysis from logs is possible, but must be carefully controlled, calculated, and qualified. Results are presented of actual uranium exploration in the field. The impact of atomic energy on world economics makes it necessary to scrutinize the applicability of all geophysical methods to uranium exploration.
STRUCTURAL AND SEISMIC DEFORMATIONS ALONG NORMAL FAULTS IN THE EASTERN VENEZUELAN BASIN
Authors: Laubscher Hans P.
Published: October 2002

Seismic reflections in normal fault zones in the Eastern Venezuelan basin usually appear distorted. Studies of reflections over fault structures delineated by drilling indicate that this is due to the similar effects of two entirely different phenomena: 1. True structural deformation of beds on the downthrown side. 2. Purely seismic distortion of reflections from underneath the fault. Analysis indicates that the structural deformations form an integral part of the fault zone; the purely seismic distortion is caused by passage of the wave through this zone of deformation.
ANTARCTIC RESEARCH IN CONNECTION WITH THE INTERNATIONAL GEOPHYSICAL YEAR
Authors: Wexler Harry
Published: October 2002

During 1957–58 a dozen nations will establish thirty‐five geophysical stations in Antarctica. Thus, this continent, whose area is larger than that of the United States and Mexico combined, will be the subject of concentrated, coordinated geophysical exploration, to a degree not dreamed possible a few years ago. For the first time geophysical stations will be established away from the coasts, deep in the interior of the continent. Scientists from the various nations will cooperate in exploring the temperatures, winds and electrical properties of an atmosphere cut off from sunlight for many months. The thickness of the ice will be surveyed and examined for indications of increase or decrease of its volume over the years, to see if Antarctic climate is changing. The Aurora Australis will be photographed and compared with its Northern Hemisphere counterpart, the Aurora Borealis. Intensive measurements will be made of geomagnetism, cosmic rays, airglow, and the ionosphere in an attempt to throw light on the physics of the high atmosphere.
SOME UNUSUAL REFLECTIONS OF SOUND IN THE OCEAN
Authors: Burling Richard L.
Published: October 2002

Occasionally, in routine seismic exploration for submarine structures, seismograms are obtained which show energy returned by something within the ocean. This effect is shown to result from relatively small, motile, gregarious objects, such as whales.