ALBERT

Notizen: The principle of the mise-á-la-masse method is to earth one current electrode of a pair in a conducting mineral show (in a borehole, in an outcrop etc.) and measure the resulting distribution of electric potentials. The distribution will, to some extent, reflect the geometry of the ore mass of which the mineral show forms a part.In a mise-á-la-masse survey of a lead-zinc deposit in Central Sweden electric potentials were measured on the surface of the ground as well as in some 25 drillholes, in either case with earthings (successively) in three different parts of the irregular ore deposit. Besides this, measurements were made in drillholes with earthings in two further drillholes.Geologic correlation between the drillholes is difficult in the present case on account of the irregular geometry of the ore deposit. However, the mise-á-la-masse measurements clearly showed the dip and the pitch of the ore body, established connections between the different ore widths encountered in the various holes, and yielded information about the shape of the ore mass.In particular, the survey showed that the ore lenses must be crescent-shaped rather than tabular, and the dip was indicated to be westerly, instead of easterly as originally presumed.Three-dimensional models of equipotential surfaces were constructed from the observed drillhole and surface potentials (using transparent plastic sheets and thin copper wire) and these helped to elucidate the mass geometry further.The surface and underground potential data collected in the present case should be of nterest to geophysicists working on analytic continuation problems.

Notizen: The author comments the techniques and methods used in continuous seismic profiling by the Monaco Oceanographic Museum during the last five years.Pinger probe give informations on the Mud layering and thickness. On the shelf or in abyssal plains, boomer and sparker are employed and allow to rise various geological conclusions. South coast of France, continental shelf in the Gulf of Lion, abyssal plain of the Ligurian Sea and Lake of Geneva are the areas concerned to with the results.

Notizen: The author proposes the parameter Δ2/ΔT1 for possible application in aeromagnetic surveying making use of already available gradiometer systems equipped with sensors separated vertically.

Notizen: Geophysical field equipment has undergone rapid changes in the past decade; from simple AGC amplifiers and galvo cameras to binary gain switching amplifiers and digital recorders, all in an attempt to keep pace with the new geophysical interpretive methods developed, and the growing acceptance of the terminology, methods, and philosophy of communication theory.The additional tools of the digital recorder and digital computer make it possible to utilize these new techniques in geophysical processing. Accomplishing these new techniques demands severe requirements on the digital field recording process in handling the decreasing energy return from the seismometer, and to fully realize the capabilities of digital techniques in reducing data. Simple automatic gain control may be used. However, in the more sophisticated interpretive methods, such as autoregression and deconvolution, it is necessary to reconstruct the actual energy levels in the computer. Recording the control signal used in master AGC or programmed gain control may prove satisfactory; however the accuracy of control versus gain is limited to I% for such analog instrumentation.To utilize the computer to its fullest extent, and to accurately perform these new techniques, requires an accuracy of I% or better. This accuracy is obtainable by using a step gain control where the gain is increased by fixed steps in which each step represents a gain in amplification by a constant factor. The accuracy in this case can be made dependent only on the tolerance of resistors used as attenuators or feedback elements. Preferably the constant factor of gain steps should be a number easily handled by the computer. By using 6 db steps it becomes a simple matter to shift binary numbers, such as multiplying or dividing by 10 in the decimal system.The requirements or parameters for such an amplifier system, and the elements of the amplifier necessary to achieve these requirements are presented.

Notizen: Consideration is given to the use of a configuration of four electrodes set in a square array for resistivity measurements.It is found that, by passing current successively between different pairs of electrodes, an apparent resistivity can be determined which is both more sensitive to the position of the array centre and less dependent on orientation than the measures usually obtained with colinear arrays of electrodes. At the same time the observations made enable the degree of the departure of local conditions from conditions of lateral homogeneity to be assessed.Theoretical and practical examples of the use of this electrode system are given and the use of the system both as a tool in mapping and in depth investigations is considered.It is shown that provided electrode spacings are suitably arranged the results of a probe carried out using the square array can be interpreted by conventional methods.The system is shown to have particular advantages in the investigation of lateral resistivity variations and the reduced dependence on orientation makes possible the recasting of interpretation data in an orientationally invariant form with a consequent drastic reduction in the number of type curves required for a particular problem.

Notizen: A large self-potential anomaly was outlined in 1963–64 at Tantahuatay near Hualgayoc in the Andes of northern Peru. Peak value recorded was–1842 millivolts–thus making it one of the strongest, or perhaps the strongest, SP anomaly ever measured. A lack of detailed geological data precludes the formulation of an adequate explanation for the Tantahuatay anomaly, but geological and mineralogical similarities with the well-documented Venencocha anomaly near Cerro de Pasco, Peru (Kruger and Lacy, 1949), suggest that the anomaly arises from sulfuric acid associated with the mineral alunite. The anomaly obviously cannot be explained by the half-cell mechanism of Sato and Mooney (1960), who place a limit of 700 millivolts on self-potential anomalies over sulfide bodies. Further study of the Tantahuatay anomaly would be of interest in understanding self-potential mechanisms in general.

Notizen: Book review in this articleF. S. Grant and G. F. West, Interpretation Theory in Applied Geophysics, McGraw-Hill Comp., New York, 1965, 583 pp., price $ 17.50.Archaeo-Physica. Technische und naturwissenschaftliche Beiträge zur Feldarchäologie. Mit Beitragen von E. Le Borgne, I. Scollar, J. D. Mudie, J. Görier, H.-J. Appel, G. Strunk-Lichtenberg, Böhlau Verlag, Köln, Graz, 1965, 202 pp., 124 fig.H. Takeuchi, Theory of the Earth's Interior, Blaisdell Publishing Company, Waltham (Mass.), Toronto, London, 1966, 131 pp.G. D. Garland, The Earth's Shape and Gravity, The Commonwealth and International Library, Geophysics Division, Pergamon Press, Oxford, London, Edinburgh, New York, Paris, Frankfurt, 1965, 183 pp., price: 17s 6d.

Notizen: The electromagnetic field radiated from a magnetic dipole lying on the ground is considered, in the extremely low frequency range (DC to 20 000 Hertz).Theoretical and experimental data are given on the characteristics of the surface wave (vanishing wave) generated at the air-ground interface, in the case of an homogeneous subsurface.The case of a subsurface with electrical resistivity varying with depth is considered.It is shown how the above-mentioned characteristics may be applied in the quantitative investigation of the electrical resistivity of the subsurface as a function of depth, in a method using the measurements on the ground of all the components of the radiated field: horizontal electrical components, vertical and horizontal magnetic components.

Notizen: Book review in this articleHandbuch der Physik/Encyclopedia of Physics, Ed.: S. FlüggeThe Aurora. By S.-I. Akasofu, S. Chapman and A. B. Meinel.Time-Variations of Cosmic Rays. By S. E. Forbush.Magnetic Properties of Rocks and Minerals. By T. Nagata.

Notizen: A formula is developed for the vertical magnetic field due to an alternating current passing through a long horizontal cable placed on a two-layer ground. The variations of the phase and amplitude ratio of the vertical field, along profiles perpendicular to the cable line are investigated. Within the limits encountered in practice, it is found that if the upper layer is conductive, as compared to the lower layer, the phase may vary appreciably whereas the amplitude ratio changes as in the case of vacuum.

Notizen: Book review in this articleN. A. Ogil'vi, D. I. Fedorovich, Groundwater Seepage Rates. English translation by N. H. Choksy, Consultants Bureau, New York 1966, 33 pp., 12 fig.

Notizen: Mapping of fault patterns is an important part of geophysical exploration. A computerized digital template analysis method is described which tests gravity maps for the effects of faults by comparing measured gravity data with calculated master curves. The interpreted gravity data are incorporated in a tectonic map using geological symbols and units, for ready use by the geologists.Tectonics can be investigated by gravity detailing if the smallest undulations on the Bouguer map are taken into consideration. Up to now, residual and derivative gravity maps have explained gravity effects by assuming spherical bodies which are almost unknown in geology. The method discussed here uses tectonic elements, such as fault-blocks and dikes as a basis of interpretation instead of the spherical bodies of the conventional interpretation methods.Gravity data can be easily and relatively cheaply obtained in the early phases of exploration by area wide spot coverage following lines of easy access such as roads, etc. Seismic studies, by contrast, have the disadvantage of being executed along predetermined profile lines. Only after sufficient detailing do seismic profiles permit-if at all -an areal mapping of faults. Thus a tectonic map is obtained only at the end of a geophysical survey instead of being available prior to the planning of costly seismic profiles. The use of gravimetric data and their interpretation by the suggested method provides tectonic detail maps in the early phases of geophysical studies.In addition, this article discusses a general geophysical interpretation method, using the investigation of faults by gravity as an example. Applications of this method for different gravity and magnetics problems as well as for combined interpretations are outlined. Detailed case histories will be published in later articles.

Notizen: To be able to make use of all existing probe interpretation techniques, it is desirable that field resistivity observations be conducted in such a way that it is possible to construct an equivalent curve for the surface variation of potential about a point source. Further, the usual parallel layer interpretation will only be justified in as much as the observed potential curve is compatible with such a subsurface geometry. Thus, whilst a potential curve may be constructed from suitable finite potential differences obtained using a Wenner configuration of electrodes, it can be shown, using the tri-potential technique of measurements, that these potential differences may arise partly from lateral resistivity variations.In this paper, a ladder network technique is employed to display these lateral effects and an adjustment method proposed to reduce them. The adjusted potential differences obtained form a consecutive series suitable for summation to give the potential function. These values are subject to further minimum adjustments required for them to comply with slope and curvature conditions for a layered medium. After forming the potential curve by summation, a final numerical smoothing process is carried out. From this smoothed potential curve, corresponding Wenner and Schlumberger curves can readily be derived for interpretation.The method proposed thus attempts to extract from the observed data the maximum part which can be reconciled with a purely depth variation of resistivity. A method is also proposed for compounding the ‘errors of closure’ of the network to provide a Lateral Inhomogeneity Index which gives a measure of the departure of the observed data from the basic interpretation requirements.The method involves no great labour, but can readily be programmed for a computer if desired. Examples are given of the application of the method to field observations. In the interest of objectivity, the final smoothing has been confined to a single stage but in certain very extreme examples a further stage may prove desirable.

Notizen: In one geophysical survey over a salt dome in the Gulf of Mexico, data taken from a single magnetic and seismic shipborne traverse demonstrated significantly the importance of magnetic measurements. The reduced magnetic and seismic profiles were integrated with gravity measurements from an earlier survey demonstrating the value of obtaining simultaneous geophysical data. The traverse was approximately 25 miles in length, 135 miles southeast of Galveston, Texas. The observed gradient averaged approximately 2 gammas per 1000 feet and crosses the southwest corner of a large shallow salt dome called the Way Dome. The recorded magnetic profile over the salt dome shows a negative magnetic anomaly extending for approximately 12 miles with a maximum amplitude of approximately 20 gammas. This negatively anomaly is due to the negative susceptibility contrast between the salt and cap rock that truncates the surrounding parent sediments. The shape of the negative anomaly correlates well with the continous seismic record and clearly delineates the topographical and structural features of the salt dome. The recorded analog magnetic profile was replotted, with both the regional gradient and time variations removed, which makes the observed anomaly much sharper than is noticeable on the original recorded strip chart record. A theoretical magnetic anomaly was calculated using a computer program for comparison to the observed anomaly. The results showed good correlation.

Notizen: Amplitudes of the vertical ground motion are larger in the critical angle region than in the near vertical region, especially amplitudes coming from deeper boundaries or interfaces with small velocity contrast. Four basic boundary models are used to derive specific travel time patterns for first order and higher order interfaces. The transition from reflected waves to diving waves in the supercritical angle region is shown for the different models.Examples from wide angle surveys in Bavaria and in the Buchara region in the USSR have many characteristic similarities. Travel time patterns and asymptotic velocities are almost identical. The most important boundaries of the continental crust - the Mohorovč Ić discontinuity and the top of the crystalline basement - correspond to two boundary models mentioned before. Amplitude and frequency investigations have been used to derive items of the M-discontinuity. It is certainly a gradient zone and seems to have a lenticular structure with material of stepwise different velocities.

Notizen: When a small, transparent replica of a seismic section is illuminated by a homogeneous beam of coherent, monochromatic parallel light a diffraction pattern is created that is representation of the double Fourier spectrum of the recorded seismic waves, i.e. their spectrum in terms of frequency, f, and apparent wave number, k.Masking selected parts of this diffraction pattern causes the spectrum to be filtered: the recomposition of the filtered spectrum then provides a filtered section.The ideal seismic section for this purpose would be a continuous variable density section obtained from recording made at every point of the seismic line. The light transmission coefficient (in terms of light amplitude) at each spot of the replica should be linearly related to the instantaneous seismic signal strength at the spot on the seismic section to which it refers.Unfortunately we cannot make recordings at every point of a seismic line and in our practically realisable recordings we have to be content with sampling in the direction of the location coordinate x. This means that with variable density recordings aliasing will be present and evident in the spectrum obtained in the direction of k; furthermore, the aliased spectrum is also multiplied by a sine function of k because the recording obtained at a given station is not presented on the seismic section as a single line along the time axis, but occupies the entire width of the trace.The diffraction patterns created by variable density recordings of dipping sine waves, including clipped recordings, and of the effect of dip filtering in such sections are discussed. The efficiency of dip rejection is shown to decrease with increasing dip.The diffraction pattern of a variable density recording is found to be characterised by a relationship between point pairs in the pattern.No such simple relationship has been found for the diffraction pattern of a variable area section; the spectra of such VAR sections belong to a very special class, because the amplitude transmission coefficient has only two values, viz. 0 and 1.Consequently, selective masking of the diffraction pattern of a VAR section may give rise to a filtered profile that does not look like a VAR section at all.General statements about the diffraction pattern of VAR sections are hard to give, because the transmission coefficient at a given point in the replica is not proportional to the signal level in the seismic section at the relevant point.In the case of VAR presentation of harmonic waves it was found that, as well as the aliasing effect in the k direction, higher harmonics of the frequency are also introduced.Some synthetic examples are given that show dip filtering to be less effective with VAR than with variable density recordings.Some arguments are advanced in favour of the opinion that high-pass filtering of VAR sections will have less success than low-pass filtering. This is demonstrated by two synthetic examples.

Notizen: The theory is explained and practical applications are shown for a numerical procedure in seismology. Particularly the problems concerning the generation of waves under the action of external pressures, and their propagation, in non-homogeneous, both elastic and absorbing media, have been carried out. These problems have been assumed mono-dimensional and refer to plane and spherical waves.The procedure is based on the solution, by means of series, of the wave differential equation, non-homogeneous, and with non-constant coefficients. It is a direct numerical method whose advantage is, mainly, the possibility of tackling, without great difficulties, problems regarding non-homogeneous elastic and absorbing media.On the contrary the methods which require the theoretical expression of the solutions by means of formulae, generally, present conceptual and numerical difficulties.As examples of application of this procedure, the following cases have been carried out by means of numerical calculations.a) Propagation of a wave, initially of symmetrical shape, in a viscoelastic medium; from the results it appears that the wave propagates without losing its symmetry, i.e. without sensible dispersion. A theoretical analysis has been carried out to justify this result, showing that the dispersion in viscoelastic media is noticeable only for relatively high frequencies. It seems that the practical absence of dispersion in field experiments do not exclude necessarily the viscoelastic character of absorption.b) Generation of plane waves under the effect of a uniform pressure distributed on the plane surface of a medium. The way the length and the shape of the generated wave depends not only on the type of pressure acting on the surface but also on the near surface impedance variations has been studied.c) Generation of a spherical wave under the action of a pressure in a spherical hole.The examples treated show how the length and shape of the wave depends on the radius of the hole. Particularly the frequencies of the wave spectrum are proportional to this radius, for a given type of pressure acting in the hole.The characteristics of this procedure would also permit the study of media for which the stress-strain relations are not univocal and linear (non linear absorption). This study, interesting for the wave propagation in rocks, is worth while to be carried out in a special paper.

Notizen: For the computation of the vertical component Hz of the magnetic field of a horizontal A.C. dipole lying on the earth's surface, a recurrence formula is presented for a horizontally stratified half space, to obtain the (n+ 1)-layer case from the w-layer case.By means of several computed diagrams for the two-layer case, Hz can be determined for different ratios of conductivity of the subsoil and that of the overburden. Thereby the distance from the dipole as well as the layer thickness h are expressed in terms of the wave length A of a plain wave in the overburden. Assuming a sufficiently large conductivity difference, the results show that evidence about the subsurface conditions can be obtained if the distance between the measuring coil and the dipole is of the order of A/3, and if the thickness h of the layer varies within the range A/100 〈 h 〈 A/6.As an example for the 3-layer case, a nonconducting intermediate layer is assumed.

Notizen: A nomogram is presented which enables evaluation of the components of magnetic attraction of a homogeneous finite rectangular prism, and of gravitational attraction due to a uniform rectangular lamina.In practice any three-dimensional body could be approximated by a number of right rectangular prisms of varying dimensions governed by the shape of the body. The magnetic attraction of the whole body is then obtained by numerical summation of the effects of the constituent prisms.For evaluating the gravitational effect, the cross-section of the body corresponding to each elevation contour is approximated by a number of rectangular laminae (or by a stepping polygon) the attraction of which can be determined with the aid of the same nomogram. The total gravitational attraction of the body is obtained by a process of graphical integration along the vertical axis.

Notizen: In [50] and [51] a theory has been developed relating formation factor, permeability and porosity of porous sedimentary rock by means of statistical parameters of the pore system, and further, tying those statistical parameters to other macroscopically measurable quantities like capillarity, capillary retention, flow dispersion etc. This paper deals with experimental methods and apparatus for checking the theoretically derived relations using columns of packed loose or artificially consolidated sands or other granular matter. Some initial experiments, mainly intended for checking out equipment and methods are reported. The discussion of the results so far shows good agreement with the theory in most cases, except for the irreducible water saturation. However, for a definite statement on the general validity of the theory more data must be accumulated.

Notizen: Some of the methods such as regional removal and second derivative calculations which can be used to outline anomalies on potential data maps can be thought of as a filtering operation. The analysis and design of such two-dimensional filters by means of direct and inverse two-dimensional Fourier transforms have been considered.An analysis of several published sets of second derivative coefficient sets indicates that, in general, they are not a good approximation to the theoretical second derivative filter. Alternate methods of designing regional removal and second derivative filters are discussed. The properties of various two-dimensional filters are further illustrated by means of maps obtained from the convolution of several of these filters with a set of observed field data. These maps show the large changes in anomaly shape which can result from the inclusion or rejection of various wavelength components.

Notizen: Integration of the continuous seismic reflection profiler with the marine refraction method on engineering surveys offers a solution to hidden layer problems, allowing both layer velocity and thickness to be computed.

Notizen: This paper is the follow-up of an earlier paper by the same author on the calculation of standard-graphs for horizontally stratified subsoils. The method which was developed in that earlier paper was destined for handwork; it was laid down in master-tables. The present paper deals with the presentation of similar methods to the computer expert in purely mathematical denotation. Two different denotations are described for the calculation of the image pole strengths involved. The first denotation is an improved version of Watsons formulae; it gives the total strengths. The second denotation preserves the character of successive approximations as described in the previous paper. Both denotations have been worked out until a six layer resistivity profile, but actually there is no limitation to the number of layers. There is no restriction to the resistivities of any layer. The only condition is now that all interface depths must be integers.This paper is followed by a paper on the relevant computer program by Argelo in this same issue

Notizen: Book review in this articleJ. Frihagen, Electron Density Profiles in Ionosphere and Exosphere, North-Holland Publishing Company, Amsterdam, 1966, price N. fls. 60,–.J. A. E. Allum, Photogeology and Regional Mapping, Pergamon Press, London, 1966, 107 pages, 16 plates, 23 figures, price 17 s 6 d net.

Notizen: High precision gravity surveys have to be examined at different points of view: the accuracy which one can expect on the final results, regardless to their distribution, the shape and amplitude of the expected anomalies, depending on these factors, which grid of stations is convenient in each particular case.Under certain condition, using an appropriate procedure, involving strict criteria, it is possible to get on the Bouguer map the same accuracy as the reading one.However an accuracy closed to 0,01 mgal does not imply that anomalies as 0,01 or 0,02 mgal deserved attention. Numerous factors limit our appreciation of significant anomalies to 0,05 mgal, may be a little less.When cavites are concerned, it is always necessary to define the extreme dimensions an depth of volumes which may give detectable anomalies.Some example are given illustrating different aspects of this particular type of geophysical prospecting.

Notizen: Several papers presented at the last SEG Convention in Houston by Schneider, Backus et al have shown how important and fruitful it was to obtain a continuous knowledge of the velocity functions and they have solved their problem by a Dynamic Correlation Analysis. Our purpose is to introduce here a method based on the best summation of a set of traces instead of the best correlation.Practically, this approach has several advantages:1) Two traces only can be correlated at each step whereas the summation can bear on any number of them;2) Optimizing the summation is actually what we are looking for since, at the long end, the success of the improvement is evaluated from the compositing of several traces either weighted or not.On the other hand, an advantage of correlation is the possibility of adding correlations obtained at several places in a same neighbourhood in order to improve the results. With the summation method this is feasible only when dips are inexistent: we shall see that the difficulty due to the dip effect can be turned around.The basic principle of the method can be summed up as follows: traces relating to a same reflection point are considered; several composites are made, each after applying different move out corrections ranging widely around an estimated adequate velocity function. At each time coordinate, the best adapted velocity function, i.e. the one that yields the best phase relation between reflected events, corresponds to the composite trace the average amplitude of which is the largest.This way, the velocity function corresponding to primary reflections as well as those corresponding to multiple reflections can be established accurately.Some examples are shown.

Notizen: The problem of elastic waves–from point sources–in layered media is solved in a general and elementary way. Only the simplest principles of the Theory of Functions are necessary. The solutions can immediately be used for numerical applications.

Notizen: The symmetry shown, by the function describing the magnetic anomaly due to a dyke or vertical fault step leads to a method by which an observed profile may be adjusted to conform with that symmetry. By making these adjustments a minimum the ideal dyke or fault profile closest to the observations is constructed. In three of four possible situations this is interpreted by simple geometry.Parallelpiped models may be transformed into two dykes for symmetry analysis. Depth limited models are not so amenable, even in special cases.

Notizen: The use of digital recorders and computers in seismic exploration promises major enhancement of the quality of final documents available to interpreters. The ultimate objectives of recording and processing remain what they always have been:1 Record the reflection wavelet as a function of time; this requirement has been met with satisfactory accuracy for a number of years.2. Record the reflection wavelets with sufficient fidelity to permit the interpreter to recognize them.Various factors affect our ability to achieve this second objective. Certain recording errors are associated with digital recording systems. However, an understanding of the sources of error will enable the operator to use his system properly and to estimate the noise level or inaccuracy of field recordings. Field operations do not require rigorous error analysis; in most cases a satisfactory approximation can be obtained from simple calculations.Three types of “noise”–seismic, instrument and power line–introduce errors. Factors which contribute to over-al recording system error include specifically input noise, power supply ripple, crosstalk, A-D conversion error, quantizing noise, aliasing, distortion. Examination of each component of a recording system, permits the determination of its ultimate effect on the over-all noise level–or error level–of the entire system.Many of the error sources produce statistically independent noise which is not correlative. Where this is true, error voltages from various sources may be combined by taking the square root of the sum of the mean square noise voltages, giving a result slightly greater than the largest single voltage if one source is much greater than any other source. This simplification can be used to estimate over-all system noise levels. Distortion and crosstalk depend on signal amplitude and should be added algebraically in each category. Each final sum should be used as a statistically independent noise source with respect to other system noise sources.Using the foregoing examples and simplified system for estimating over-all system noise, and assuming that much of the distortion (which limits signal/instrument noise ratio to 54 db) can be removed by filtering, we determine that the combined effect of all sources of error is to reduce the system S/N ratio to approximately 74 db.With proper care digital field recording systems can produce very good field records, and exotic computer processes can enhance signal and reduce various forms of noise. However, one always must recall that the level of confidence which one can place in an interpretation of seismic data must be dependent on a knowledge of the accuracy of the basic data.

Notizen: The Terrapak is a new seismic energy source of the surface energy source type. Essentially, the Terrapak consists of a compressed air piston which transmits a shock to the ground by means of a striker plate attached to the piston rod. The Terrapak is truck-mounted together with its ancillary equipment. Shocks can be generated at 8 second intervals, and although the weight of the striker is relatively low (approximately 1400 Ibs) the impact velocity exceeds 66 ft/sec. The energy available is about 85,000 ft. lb., which is equivalent to that produced by conventional weight-dropping methods. The power spectrum of the seismic wave produced by the Terrapak is spread out towards the higher frequencies because its impact velocity is greater than that of a dropping weight.There is a noticeable difference between noise records made with the Terrapak and noise records made with a conventional weight-dropping technique. The same noise frequencies are found in both cases, but low frequency noise is stronger with weight dropping than with the Terrapak, whereas the intermediate frequency reflections obtained using the Terrapak are more suitable for correlation.The expansion of the compressed air generates a sound wave, the effects of which must be eliminated by the use of multiple geophone arrays. A spectrum analysis of the records has confirmed that the waves produced by the Terrapak are rich in intermediate frequency components. This facilitates the picking of reflections in normal areas where the apparent frequency of the reflections is about 30 to 35 c/s.

Notizen: This paper includes publication of two algorithms, to be processed on a digital computer. The algorithms are based upon the two mathematical denotations, presented by Dr. J. C. van Dam in this same issue. The computer programs are written in Algol, in the form of procedures (i.e. subroutines to be activated from a surrounding Algol program).Each of the two procedures is preceded by a numerical analysis. Some remarks are made about the reliability of each of the two procedures, the production and the computing time required.

Notizen: The theory of statistical communication provides an invaluable framework within which it is possible to formulate design criteria and actually obtain solutions for digital filters. These are then applicable in a wide range of geophysical problems. The basic model for the filtering process considered here consists of an input signal, a desired output signal, and an actual output signal. If one minimizes the energy or power existing in the difference between desired and actual filter outputs, it becomes possible to solve for the so-called optimum, or least squares filter, commonly known as the “Wiener” filter. In this paper we derive from basic principles the theory leading to such filters. The analysis is carried out in the time domain in discrete form. We propose a model of a seismic trace in terms of a statistical communication system. This model trace is the sum of a signal time series plus a noise time series. If we assume that estimates of the signal shape and of the noise autocorrelation are available, we may calculate Wiener filters which will attenuate the noise and sharpen the signal. The net result of these operations can then in general be expected to increase seismic resolution. We show a few numerical examples to illustrate the model's applicability to situations one might find in practice.

Notizen: In order to adequately understand the complicated, anelastic processes governing wave propagation in soils or highly weathered rock it seems desirable first to have available a convenient laboratory material for such propagation studies the frequency dependent rheological parameters of which are known beforehand. A property measurement program has been conducted to determine the complex Young's modulus and the complex shear modulus of a commercially available viscoelastic material over a broad spectral region.

Notizen: In the year 1958 the Service for Water Management of the „Rijkswaterstaat” started its program of geo-electrical resistivity prospecting in the western part of the Netherlands. The aim of this program was to obtain data on the salinity distribution of the ground water.The ground water regime in this part of the Netherlands is most intricate. This is due to the geological and geo-hydrological conditions and to the low elevation of the land. Many reclaimed areas are up to several metres below mean sea level.The resistivity data obtained are closely related to the salinity of the ground water. On the basis of bore hole data it was even possible to arrive at calibration curves for the salinity of the ground water in sand deposits. Under special conditions it was also possible to draw conclusions with respect to the presence of less permeable formations as e.g. clay layers.Some remarks are given on the practical performance and the interpretation of the measurements.A review is given of the work done until now. Some results are shown by means of maps of the salinity distribution of the ground water in the western and northern parts of the Netherlands.Two examples are described of the use of the data obtained during the survey in the province of Zuid-Holland.Another two examples are presented of detailed investigations for special purposes in relatively small areas.

Notizen: In mountainous areas it is an inadequate procedure to reduce gravity observations by merely subtracting the effect of an infinite flat slab of material between the station and sea-level, and adding a terrain correction. A programme is described which directly computes the effect of masses above sea-level, and mass-deficiencies below it; as well as the effect of compensating masses under the Pratt and Airy isostatic systems. As an example, the method has been applied to a regional gravity survey of Papua and New Guinea where it is seen to remove the usually high correlation of the Bouguer anomaly with local topography.

Notizen: A shallow, wide spread perching layer was isolated in the alluvial profiles of western Fresno County, California. Geologic and hydrologic interpretations are given, based on field and laboratory measurements of the physical properties of this layer. Some of the approaches investigated included using existing electrical logs from irrigation wells, head loss observations in wells and piezometers, core drilling, and core analysis. Differences in alluvial profile permeabilities are shown which result in perched water under the existing field flow conditions. The quantity of vertical flow through the layer is estimated using core permeabilities and hydraulic gradients observed in the field.Hydraulic properties and descriptions for the perched zone are presened which can be used to delineate profile flow limitations at other locations in the San Joaquin Valley. The study may be used in estimating the rate at which this perched water table could rise If, in the future, imported water and changes in irrigation patterns cause a large quantity of water to flow vertically.

Notizen: The most commonly practiced method of artificial recharge at present is through basins. This spreading method may not be physically feasible or practicable if land values are high or a shallow, densely compacted layer forms a barrier impeding the direct downward percolation of the ponded surface water.For the case of the latter condition, alternative methods of wells or trenches dug down to the pervious aquifer and backfilled with gravel have been investigated. These were explored from the standpoint of construction and operating cost and hydraulic efficiency as influenced by such factors as the depth to the aquifer, the thickness, depth of saturation, permeability and specific yield of the aquifer, interference of closely spaced wells and duration of continuous operation of the wells or trenches. Furthermore, effects of bacterial growth and chemical composition of the recharge water on the hydraulic performance of wells or trenches are discussed.An economic comparison based on field conditions in a prospective recharge site at Stockton, California, is used to illustrate the developed criteria for relative effectiveness of the two methods.As a general conclusion, it was found that while recharge through trenches would be more efficient hydraulically and economically for the case of very shallow subsurface barriers, wells would become more competitive as the thickness of an impervious top layer increases.

Notizen: The horizontal viscous flow model with “infinite” areal extent can be used for almost any well flow problem whether two-dimensional or three-dimensional, steady or nonsteady, single aquifer or multiaquifer. This model can also be used in the field of soil mechanics for subsurface drainage problems. The design includes scale model analysis and the application of conformal mapping techniques in order to simulate an ideal aquifer. Construction, calibration, and test procedures for the model are described. The apparatus has proved to be both a valuable research tool and an excellent teaching aid.

Notizen: One of the deepest water-exploration wells in the southeastern United States was completed in 1966 at Jacksonville, Florida. It was drilled to a depth of nearly 2,500 feet to supply geologic and hydrologic information on the deeper unexplored part of the Floridan aquifer. This aquifer consists of a series of water producing zones separated by nonproducing zones. An important new fresh-water producing zone was found, and the contact between the fresh water and salt water was located. The well was completed in three separate zones so that it could be used to monitor the the deeper part of the aquifer to detect any salt-water encroachment. This paper describes the objectives, techniques, and results of drilling the test well.

Notizen: A rapid graphical technique for the determination of aquifer transmissibility from a variable discharge pumping test is presented. The data required include the variation of discharge with time during the pumping test and a record of the recovery ar an observation well after the well was shut off. An example using a synthetic well data is provided.

Notizen: Comparison of the analysis of 3 and 4 day pumping tests with the analysis of water-level changes due to 18 years of pumping suggests that experience in an area can be a critical factor in determining the transmissivity and storativity of an aquifer.

Notizen: The rapidly increasing development of ground-water resources in northeastern Illinois has brought about regional and local problems of water supply, thus creating considerable interest in the feasibility of artificial recharge as a partial solution. Artificial ground-water recharge is considered as a partial solution to regional and local problems of water supply in the primarily metropolitan region of northeastern Illinois. Five artificial recharge facilities are now in operation in the area; their average annual recharge rates range from 25,000 to 395,000 gallons per day (gpd). Several additional areas where artificial recharge may be feasible are identified on the basis of criteria established for the region.An initial study in the Park Forest-Chicago Heights area indicates that recharge to the Silurian dolomite aquifer, the source of water supply in the area, is feasible. This study provides guidelines to aid in additional studies of artificial recharge in northeastern Illinois.

Notizen: Two case histories are presented which illustrate that by analyzing drill cuttings or bailed samples, by knowing total depth of a test hole and position of the static water level, and by studying the driller's log, not only can a well's yield be predicted—but also drawdown may be predicted for any well in advance of a pumping test.The estimation of specific capacity (gpm/ft of drawdown) is invaluable in well design, particularly in the United States, where drilling contractors work rapidly and efficiently. Knowledge of probable specific capacity can aid in recommending proper screen length, diameter, slot width, and setting. It will enable cost estimates for proper pump size to be made, for casing requirements to be determined, and also for ultimate well diameter and depth to be determined. Test-pump setting can also be anticipated.Case History No. 1 illustrates the above techniques, and how a new well was drilled, developed, designed, and completed adjacent to a poorly designed and equipped water well. The new well proved to be nine times more efficient (i. e., “better”) than the old well. Reasons for this improvement are shown, and the two wells are compared and contrasted.Case History No. 2 shows data from a constant-rate pumping test following calculation of a well's specific capacity using estimates of aquifer permeability. Analysis of dynamic water-level recovery measurements resulted in a transmissibility of 16,150 gpd/ft compared to an estimated 16,000 gpd/ft from a visual inspection of sand analysis grading curves. The well's specific capacity was estimated to be between 8.4 and 8.9 gpm/ft of drawdown. The measured specific capacity was 8.35 gpm/ft with an efficiency of 85 percent. Actual permeability was 230 gpd/ft compared to the estimated 228 gpd/ft2!Six figures are included showing well construction details, sieve analysis curves, a semi-log plot of recovery measurements obtained during an aquifer pumping test, and graphic representations of approximate permeabilities for granular materials ranging from clay/silt to fine gravel. Six tables give characteristics of samples recovered from two test wells, permeability estimates of the disturbed samples, approximate permeabilities of various granular materials, and specific capacities for 100 percent effective water wells with varying diameters, coefficients of storage, and pumping periods. Three photographs further illustrate the principles enumerated.The methods described can give acceptable results (although they may not be as spectacular as the two detailed case histories) if sound judgement is used; if local conditions are somewhat known; if sampling methods are described; and if the procedures are not abused by expecting extreme accuracy. A reasonable estimate, or perhaps, just a close scientific “guesstimate” is all that should be hoped for by the hydrogeologist and his client in predicting well yields. But these techniques are a great advance over the“forked peach stick” philosophy still used for similar purposes by pseudo-scientists in the United States and foreign countries (although no cases where a dowser or “water witch” has successfully predicted drawdown in addition to yield have come to the attention of the writer).The data in this report are derived from approximately 500 wells or more designed by the author in 26 States and in many locations abroad. Rather good success has been obtained regarding close correlation between estimated and measured specific capacities from a variety of geologic environments and aquifer parameters.

Notizen: The intensively irrigated Arkansas River Valley in Colorado is underlain by a valley-fill aquifer resting in a U-shaped trough cut in relatively impermeable Cretaceous rocks. Ground water is pumped to supplement surface water; in the last 10 years pumping has more than doubled. Ground water is closely related to the Arkansas River; percolation from irrigation recharges the aquifer, which discharges into the river. Pumping has resulted in a reduction in streamflow because it intercepts water that ordinarily would have reached the river. The 1,500 irrigation wells in the Arkansas Valley withdrew 230,000 acre-feet of water in 1964.An analog model is being used to evaluate the relation of ground water to surface water and to predict effects of changes in water management. The model, simulating a 150-mile reach of the Arkansas Valley (Pueblo to the State line), has a resistor spacing of 8 per modeled mile. The framework for the model was a transmissibility map; transmissibility ranges from less than 50,000 to 700,000 gallons per day per foot. Specific yield averages about 0.2. Hydrologic boundaries, such as the Arkansas River, and the bedrock valley-fill contact were simulated. Applied water, precipitation, evapotranspiration, and ground-water pumping were the independent variables programed. The model is being verified by comparing predicted changes in water level and river discharge with observed changes.

Notizen: A method is presented for computing maximum drawdown in a well being pumped intermittently but in accordance with a regular sequence of fixed periods of pumping at constant discharge followed by fixed periods of rest. The method is extended to allow for interruption of the basic pattern by occasional changes such as the elimination of the pumping phase from certain individual cycles.

Notizen: The ever-increasing volume of information being collected by the Groundwater Division of the Research Council of Alberta required that a data storage and retrieval system be devised to handle this information in an efficient and economical manner.The HYDRODAT computer-oriented system developed for this purpose is a modification of the format developed by the United States Geological Survey and conforms to the proposed interagency compatibility requirements set forth by the Canada Department of Energy, Mines and Resources.The basic elements of the system are: a well-schedule form for the recording and coding of geologic, hydrologic, and water quality data; and five 80-column IBM punch cards for transferring the coded data to magnetic tape.Selective and rapid retrieval of large volumes of ground-water information using HYDRODAT provides the geologist and engineer with analytical methods which would otherwise be tedious, if not impossible, to apply by conventional methods.

Notizen: Water as a natural resource has little value until somebody wants to use it and the dollars and cents value has normally been established by the costs of moving water from its source to the point of beneficial use. The value of water ranges within wide limits from perhaps $2 per million gallons to $70 to $100 per million gallons and an average value might be $20 to $30 per million gallons. Water is no longer free and the costs of providing water in adequate quantity and of suitable quality will increase in the future as the sources of water are more fully utilized and the needs for more extensive treatment increase. The decision to use surface water or ground water is usually based on availability and the costs of providing the water at the point of use for the lowest possible cost. In estimating such costs, however, all costs of development, construction, treatment, operation and maintenance must be included. The principal advantages of ground water include availability close to the point of use, usually lower treatment costs, lower capital outlay, ability to increase the supply by small increments and smaller property requirements for storage. Ground water is often preferred because of its constant chemical quality and temperature. It is the opinion of the author that the effects of the impending water shortage can be minimized by elimination of pollution of our available water supplies and greater use and better management of our ground-water supplies including natural and induced recharge.

Notizen: The ground-water aquifer underlying the northeastern corner of Colorado presently is estimated at 80,000,000 acre feet — enough to last several decades at present rates of use. The rate of use has, however, been increasing substantially in recent years and the possibility of depleting this resource is very real. While depletion of stock resources is a common theme in conservation and natural resources literature, only a few empirical studies are available to show the economic consequences of alternative rates of use. As a result, ground-water policy has often lagged behind the needs of developing areas.The Economics Department at Colorado State University, under the auspices of the Office of Water Resources Research is currently engaged in an empirical study of ground-water development problems in Colorado's High Plains area. Research is just beginning, but the following themes will be examined:〈list xml:id="l1" style="custom"〉1The economics of common property resources and the different management problems associated with them.2Problems faced by individual farm operators as they make the switch from dry-land to irrigated farming. Problems of externalities among farm firms will be approached.3Problems likely to be faced by inhabitants of communities in the developing area. The integration of the agricultural with the non-agricultural sectors will be stressed.4Policy recommendations appropriate to areas of rapid ground-water development.While the activities at Colorado State University are confined to a relatively small geographic area, it is assumed that applications will be made broader in scope and will prove useful in other parts of the nation.

Notizen: Watercourse aquifer systems in many areas are adversely affected by wastes disposed into surface-water sources, resulting in either reduced streambed permeability, infiltration of wastes into the aquifer, or both. These conditions are illustrated at Lancaster, Ohio, where low streambed permeability in the vicinity of the municipal well field, resulting from the discharge of wastes to the Hocking River, seriously retards the infiltration of surface water and lessens the available yield of the wells. The wastes consist of brine and iron-laden effluent from the municipal treatment plant, discharged within the area of influence of the pumped wells to a stream already carrying much organic waste and other debris. Upstream from the discharge sewer, muck and organic debris have accumulated thickly on the streambed, while downstream from the sewer the streambed sediments have become tightly cemented by iron and other constituents in the waste water. There is evidence that, despite reduced streambed permeability, wastes have entered the aquifer and have materially contributed to declines in well efficiency and to recurring problems of well maintenance.Conditions such as those illustrated at Lancaster occur also at Dayton and are not uncommon elsewhere in Ohio. Indirect contamination of aquifers and adverse physical and chemical alteration of streambed sediments, resulting from surface-water waste disposal, may in many places pose a threat to the ground-water supply. This fact should not be overlooked in determining water-quality standards to be established under the Water Quality Act of 1965.

Notizen: The Geological Survey has been the foremost agency in the investigation of ground-water resources in the United States beginning about 1910. Most of the basic principles of modern ground-water hydrology were developed in the Survey's program of cooperative investigations.Use of ground water in the United States in 1960 was about 17½ percent of all water uses, excluding water power. The use will probably increase, though at a decreasing rate. Although amount of use may level off, the need to know about it will not.While coordinating its activities with those of the Office of Water Data Coordination and the Office of Water Resources Research, the Survey expects to step up its work in all three areas of data collection, investigations, and research. However, there will be changes of emphasis.Collection of raw data will tend to stress key observation points, and more and more observation of temperature and quality, including contaminants. Investigations will be aimed at upgrading reconnaissance coverage to general coverage for most of the Nation. The areal basis will be stream drainage basins and special hydrologic terranes, rather than political units. There will be an increase in the preparation of analog models for representative ground-water systems.In research, the problem-oriented basis will continue. Stress will be on basic principles that pertain to artificial recharge, and the natural recharge and discharge of ground-water reservoirs; and also on the application of geologic principles on a regional scale. These are critical elements in the management of surface-water and ground-water resources conjunctively in river basins.

Notizen: Acidizing water wells to increase yield has proved to be an uneconomical method of well development or rehabilitation in some cases where the aquifer permeability was low and normal operating head great, in wells affected by methane gas, or where the practical sustained yield of the aquifer had been exceeded. Illinois studies show that controlled pumping tests before, during and after development are necessary to accurately evaluate the effectiveness of rehabilitation methods employed. Geologic definition of aquifers and records of pumpage and water-level information are invaluable aids.

Notizen: The relation between water quality and water movement within the ground-water reservoir may be better understood if studies of flow systems are used in conjunction with hydrochemical methods. Within small watersheds, local, intermediate, and regional flow systems may develop, depending upon the shape, the relief, and the thickness of the ground-water reservoir. Lateral and vertical variations of water quality in the ground-water reservoir reflect the difference in length of flow paths within a system. The relative ion concentration of the major ions in solution in ground waters change as water moves from recharge areas to discharge areas. These changes are used to interpret the direction and rate of ground-water movement.Ground-water types mapped in the Two Rivers watershed of northwestern Minnesota indicate that calcium bicarbonate type water occurs near the source of recharge and progressively changes to the sulfate type as water moves downgradient toward the discharge area. Local recharge areas are indicated by the greater penetration of calcium bicarbonate waters into the ground-water reservoir. The calcrum bicarbonate type water of surface streams during low flow indicates that water moves into the stream from the upper part of the ground-water reservoir. Chloride type water moves from the Paleozoic rocks and mixes with water in the glacial drift probably at places where permeable zones in the Paleozoic rocks are in contact with the overlying drift.

Notizen: This study of the geometry of limestone solution is based on the following conditions: (1) the limestone is impermeable but contains and transmits water in joints, fractures, bedding-plane partings, and solution channels; (2) at depth, the limestone aquifer is underlain by impermeable rock; (3) ground water in the limestone is under water-table conditions; (4) recharge to the limestone is by infiltration of precipitation through the overlying rock to the zone of saturation; (5) discharge from the aquifer is by seeps and springs; and (6) ground water dissolves the limestone through which it flows, continuously modifying the flow pattern and the hydrologic properties of the medium. These conditions commonly are found in limestone terranes in the eastern and central United States. An electrical analog was constructed conforming to this description of the ground-water flow system and has been used to define the pattern, velocity, and density of ground-water flow and the relative length of time of contact of water with the aquifer. Successive models are used to illustrate progressive limestone solution and changes in ground-water flow in the aquifer. The initial analog indicates a strongly convex water table with the greatest density of flow at shallow depths beneath the water table near the point of discharge. Successive models indicate greater concentration of flow near and on the level of ground-water discharge, an overall lowering of the water table, and a pronounced flattening of the water table near the discharge point.Results of the analog study support the following conclusions:(1) The most active zone of solution is at shallow depths beneath the water table and near the point of ground-water discharge. Consequently, the size of channels generally decreases with depth and increases with proximity to the point of ground-water discharge.(2) Generally, solution channels have a greater lateral than vertical extent.

Notizen: The need for investigating the economics of groundwater pumpage was developed to aid in the interpretation and administration of the Kansas Water Appropriation Act. The Act requires that in determining impairment from the lowering of static water level, the economics of pumping water shall be considered. No comprehensive treatment of the subject matter has been found.The investigative work is presented in three parts consisting of ground-water interference, the definition of general cost functions, and the effect of interference on costs. The physical process of ground-water pumpage for a single well in both steady-state and nonsteady systems is used as a beginning basis for both interference and associated costs. Interference between multiple wells is then developed for both idealized states of condition. In the second part, economic parameters with associated costs, primarily for irrigation use of water, are developed and generalized cost functions given in terms of discharge, total head, and operating time. In the third part, an analytic model is developed to define the costs associated with mutual interference. The procedure has been tested on a limited number of examples to find the relative sensitivity of different parameters on costs.

Notizen: The Sokoto basin in semiarid northwestern Nigeria contains Cretaceous and Tertiary semiconsolidated deposits that dip gently northwest off an oldland of pre-Cretaceous crystalline rocks. Until recent years the dug well has been the chief source of ground water for the Hausa cultivators and the pastoral Fulani inhabitants of the region. Borehole exploration sponsored by US AID and the Geological Survey of Nigeria with technical guidance from the writers of the U. S. Geological Survey has revealed that the basal section of the Gwandu Formation contains a productive artesian sand aquifer throughout a 5,700 square mile area. Transmissibilities of the aquifer proved to be as high as 180,000 Imperial gallons a day per foot but generally decrease towards the west. The free flow areas total about 1,000 square miles with pressure heads in boreholes up to + 83 feet above land surface and individual flows as great as 12,000 gallons per hour. Beneath the Gwandu, pressure aquifers in the Rima Group and the Gundumi Formation also produce flowing water in the lowland (fadama) of the Sokoto River. In the southern part of the basin, however, only one aquifer is present in the Cretaceous sequence, because the Gundumi aquifer is absent and the Rima aquifer apparently grades into the upper permeable section of the Illo Group. The quality of the water from all the pressure aquifers is generally quite good, although the iron content is high in places and salinity increases in the very deep aquifers.In Sokoto Province more than 2 million people and their livestock use less than 5 mgd of water drawn from dug wells and about 1 mgd from boreholes. The newly discovered flowing artesian water can do much to improve the water supplies of remote villages in the province and even supplement river irrigation during the dry season in the fertile fadama.

Notizen: Valley City, North Dakota, has an average daily water use of 750,000 gallons, which is obtained from wells tapping pattly confined gravel deposits in the Sheyenne River valley. These deposits at Valley City have a maximum thickness of more than 50 feet and an areal extent of approximately 1 square mile. The aquifer has been artificially recharged successfully since 1932 by diversion of water from the Sheyenne River to an abandoned gravel pit. During this time the piezometric surface in the aquifer has been raised more than 22 feet.Prior to 1958, the recharge system was operated from January until June; however, when the piezometric surface rose to within about 8 feet of the surface, the recharge operation was discontinued. Between June and January the piezometric surface declined as ground water was withdrawn. During the recharge-discharge cycle, the average annual fluctuation of the piezometric surface was 10 feet, amounting to a change in storage of about 1,000 acre-feet of water. Since 1958, the recharge system has been operated throughout the year. There has been a gradual improvement in the quality of the water in the aquifer since the installation of the recharge system.

Notizen: Observations of temperature, pll, specific conduction, and discharge, and concentrations of calcium, magnesium, potassium. lithium, and sodium in the discharge of a flowing well reveal that geochemistry of aquifers should be based on sample wells which have been allowed to discharge for an extended period.

Notizen: A systematic investigation of the steady-state discharge to wells that partially penetrate a homogeneous and isotropic non-leaky artesian aquifer was made using an electrolyte-tank model. The experimental results were compared with the discharge calculated by methods developed by several previous writers. This comparison showed that the formula of Li, Bock, and Benton (1954) gave the most reliable results over the widest range of the appropriate geometric variables.

Notizen: The outlook for Congressional legislation resolving iong-time controversies over waters of the Colorado River, optimistic in 1966, has been dimmed by political misunderstanding. The essential ingredient of progress -harmony between Arizona and California water leaders -has been lost. They worked together on a bill to bring peace to the river and economic advantage to themselves and all Lower Colorado River Basin States. They got to the threshold, but not across it.Unless falling short of complete success has irreparably upset the delicate balance of Arizona-California interests, they must inevitably rejoin forces to reach their mutual goals. When and if they do, we believe the background for action and the proposed legislation outlined here will continue to be their best means of compromise.

Notizen: A method is presented for determining values of u and W(u) for u greater than 0.01 from time-drawdown data without the use of graphical approximations or type-curves. The method utilizes the function Z(u) which is defined in the paper and makes possible the application of statistical analyses of test data for bounded aquifers and other types of complex field problems. If the field data are taken so that t is a consecutive multiple of two, the method can be applied directly to the drawdown observations. An example of this method used to analyze test data for a bounded aquifer and a table of values of W(u) and Z(u) for selected values of u between 0.01 and 4.6 are also presented.

Notizen: Estimates can be made of the distances to hydrologic boundaries by using water-level measurements from pumping wells and by assuming in each case the possible range of the coefficient of storage. Interpretation of pumping test data from Well 6 (J-13) at the Nevada Test Site implies that a fault 1200 feet from the well acts as the closest of the impermeable boundaries. In a case where no boundary has been felt the areal extent or volume of rocks affecting the drawdown pattern of a well can be estimated by assuming that a hypothetical boundary is just about to be felt at the time pumping stopped.

Notizen: Criteria and formulas are presented for scheduling cyclic pumping operations, to maintain a given minimum drawdown as required for drainage purposes. Keeping the total cycle length constant, the pumping periods are successively shortened and the shutoff periods lengthened. Solutions of the equation for the relative length of the shutoff periods are presented in a family of curves, which greatly simplifies the scheduling procedure.

Notizen: The failure or “breaking up” of pavement in cuts in glacial till is a phenomenon commonly observed in northeastern Illinois and other areas in the midwest. Failure commonly follows periods of significant ground-water recharge, especially when such periods are concomitant with freezing and thawing conditions.Water levels in piezometers installed in glacial till in northeastern Illinois indicate that during periods of high precipitation or rapid snow melt, the potential surface normally occurs at shallow depths. Therefore, cuts of appreciable depth intersect the zone of saturation and establish local, gravity, ground-water flow systems with the bottom of the cut acting as a ground-water discharge zone. Such shallow gravity flow systems may bring about pavement failure by facilitating the growth of thick ice lenses or by developing high pressure beneath the pavement due to poor drainage.

Notizen: The scope of area1 investigations of water resources in New York has changed within the last 4 years. Prior 1962, most investigations covered only counties or smaller areas and were mainly restricted to ground-water resources Since 1762, investigarions have covered largebasin (2,000-4,000 square miles) with the purpose of defining total water resources so that basin-wldc comprehensive plans for water development can be prepared.Ground water has been intensively studied in the basin investigations, both because of its large potential for future development, and becaus e of it sinterre lation with the surface-water resources. The latter reason is particularly important because the principal aquifers are numerous u nconnect edglacials and andgravel deposits that are crossed by streams. This ground-water regimen to a large degree determines the flow characteristics and water quality of streams. Conversely, streamflow data provide acon-venient means of assessing ground-water availability.Some approaches used in basin studies are:(1)(1) numerous quantitative and qualitative observations of low streamflow to define the principal areas of ground-water discharge and to define the quantity and quality of discharging ground water(2)estimation of total ground-water dischar gepas stream gages from daily streamflow records by correlation with ground-water levels and by analysis of the records(3) assessment of recharge to particular sand and gravel deposit swith inbroadlimits, using the data on ground-water discharge to streams(4) estimation of a daily chemical quality hydrograph on the basis of quantity and quality of both ground-water discharge and overland runoff

Notizen: Passive-element electric analog models have been used for many years as a means of tudying cause and effect relationships in the regional development of ground-water resources. Although successful use of such models has been demonstrated by several investigators, certain inherent characteristics designed into some electric analog models lead to significant error at particular boundaries of the model.Errors that exist at the pumped well junctions of non-steady-state two-dimensional flow electric analog models are analyzed. The results of the analysis indicate that practical sustained yields and water-level data derived from pumped well junctions of electric analog models lead to overly optimistic estimates of aquifer and well yielding capabilities. This paper presents design methods for simulating pumped wells having different radii, screen lengths, partial penetrations, gravel pack sizes, and well-loss constants.

Notizen: Geologists increasingly concerned with detailed laboratory analyses at times overlook space-age techniques that promise the collection of valuable sedimentological data. Orbital remote sensing, and particularly space photography, can provide synoptic environmental data for geoscientists including those familiar with applying aerial photography to the analysis of sedimentary environments. Color space photographs obtained incident to the Gemini Program provide unique tools for analyzing sedimentary environments and processes and provide data that cannot be duplicated by conventional aerial photographic techniques. The principal advantages of orbital geoscience data collection include frequency of coverage leading to environmental analysis within the full spectrum of seasonal contrasts, and opportunities for environmental syntheses by synoptic observations. Gemini space photography is an available source of semi-quantitative data concerning changing environmental phenomena and mechanisms of sediment distribution. It also enables the survey and inventory of global sedimentary landforms. With the application of advanced sensors, increased system resolution, and repetitious photographic coverage, speedier and more reliable quantitative sedimentological analyses can be performed.

Notizen: Book reviewed in this article:Essays in Geomorphology. G. H. Dury.The Movement of Beach Sand—Developments in Sedimentology, 5. J. C. Ingle Jr.Manual de Sédimentologie. A. Vatan.Carbonate Rocks—Developments in Sedimentology, 9A. G. V. Chilingar, H. J. Bissell and R. W. Fairbridge (Editors).Cyclic Sedimentation—Developments in Sedimentology, 10. P. McL. D. Duff, A. Hallam and E. K. Walton (Editors).

Notizen: Books Review in This Article: Carbonate Rocks—Physical and Chemical Aspects—Developments in Sedimentology. 9B. G. V. Chilingar, H. J. Bissell and R. W. Fafrbridge (Editors)

Notizen: Saxena (1966a) proposed that zircon could be authigenic and low-grade metamorphic, as well as magmatic in origin. He questioned the mechanical and chemical stability of zircon, the use of crystal morphology in correlation, and the use of roundness as a criterion of detrital origin. In so doing, he challenged the role of zircon in problems of stratigraphy, pedogenesis, and sedimentary, igneous, and metamorphic petrology.SAXENA'S(1966a, b) evidence for authigenic and low-grade metamorphic zircon is unconvincing, since conventional explanations adequately encompass his obser- vations, and do not conflict with established knowledge of zircon behaviour.During weathering, authigenesis, and metamorphism, zircon is shown to conform with the concepts that:(1) its removal and transport in solution is minimal, (2) zircon formation during authigenesis and low-grade metamorphism is insignificant. Rare occurrences of hydrozircon confirm this paucity of authigenic zirconium minerals. At high metamorphic grades zircon-transformation is favoured by the “wet” metasomatic processes of the amphibolite facies and impaired by the “dryness” of the granulite facies. The occurrence of zircon transformation in the granulite facies may also be prevented by incorporation of zirconium in the lattice of newly-formed pyroxene. Release of this zirconium during diaphthoresis of pyroxene-bearing granulites could give rise to new zircon.The formation of zircon during authigenesis, and its formation and transfor- mation during low-grade metamorphism, would diversify initially homogeneous assemblages; but Saxena has failed to prove that either process does in fact occur. It is contended that, since the positive correlation of zircon assemblages from co-eval sedimentary and metamorphic rocks of the Kingsbridge area is opposed to Saxena's views regarding the origin and behaviour of zircon, the roles of authigenesis in the formation of zircon, and of low-grade metamorphism in its formation and transformation, are insignificant or non-existent.

Notizen: Lithogenesis of the Steinmiihl Limestone of the Arrach Quarry (Jurassic, Austria)The Upper Jurassic Steinmuhl Limestone Group on its type section (Arrach Quarry, Lower Austria) is subdivided into the following four members: 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:00370746:SED23:SED_23_mu1"/〉 These various sedimentary units represent a gradual change in the environments during sedimentation. The sequence sets in with the Filament Limestone. It possibly represents a sublittoral Lamellibranchiata debris and is of Callovian (?)age. Though the marine deposition continued without interruption to the Upper Jurassic, the environment changed markedly. The sea became deeper and the Filament Limestones were followed by pelagic-bathyal Radiolaria Siliceous Limestones. A distinct difference in the degree of subsidence within the Upper Jurassic geosyncline led to the formation of bathyal furrows and swells. Over the latter the calcilutite Saccocoma and Calpionella Limestones with mainly pelagic fossils were deposited in Kimmeridgian and Port- landian. Their thickness is small, for currents swept much sediment into the deeper furrows, in which the Oberalm stratas arose in great thickness at this time.

Notizen: A combined petrographical and geochemical study has been made on a per- sistent carbonate horizon from the Mansfield Marine Band, an important marker horizon in the Westphalian Coal Measures of the east Pennines. The composition of this carbonate is unusual for it normally consists of ankerite, but in some localities the carbonate is siderite and not ankerite. The position of the carbonate in the sedimentary cycle is discussed and the conclusion drawn that physicochemical conditions were suitable for the precipitation of CaC03 to occur. Furthermore the detrital material in the carbonate band continued to accumulate at a similar rate to the shales above and below the carbonate. The alteration of the CaC03 is thought to have been a diagenetic effect and the result of a change in the physicochemical environment. Variations in the concentration of dissolved sulphur species and their effect on the solubilities of iron and manganese provide an adequate mechanism to explain how CaC03 may alter to siderite on the one hand or ankerite on the other.

Notizen: The sand size carbonate fractions of beach and dune sands from the southeastern U.S. Atlantic coast were investigated from the standpoint of mineralogy, roundness and size distribution. The carbonate fractions of beach-dune sands used in this study range in abundance from less than 1% to over 40% and average about 10%. Calcium carbonate is least abundant in Georgia beaches and increases slightly to the north and greatly to the south. The size distribution of the carbonate fraction is similar to that of the non-carbonate fraction since both have been distributed by the same processes. The variable flat shape of calcareous fragments causes the carbonate fraction to be usually coarser and more poorly sorted than the acid insoluble residues of the samples. No regional relationship between roundness and wave energies was found in sand size materials although field observations indicate high energies strikingly round gravel sized calcareous fragments. There is some tendency for angularity to increase with decreasing grain size in the sand sizes as with quartz grains. The mineralogy of beach sand carbonate fractions is characterized by the almost total absence of high My calcite. Aragonite is the dominant mineral.

Notizen: Quartz grain surface textures from the basal glauconitic chalk of the Belemnitella mucronata Zone southwest of Belfast, Northern Ireland, show the effects of solution during the last stages of diagenesis of the limestone. The postulated chemical environment, in which quartz is more soluble than calcite, is one of moderate temperature and pressure and alkaline circulating ground water.

Notizen: Two samples of plant-rich limy sand collected from the 9- and 11-ft.-level of the Heron Island cay were subjected to 14C dating. Uncertainties related to secondary changes and contaminations, and the unknown transportation history of the woody material prior to accumulation at Heron Island, in combination with the relatively young age of the carbon, did not result in 14C values useful for correlation and absolute dating purposes.

Notizen: The following dimensionless parameters (two of them well-known and five of them new) are defined for determination of ripple mark geometry: ripple index (RI), ripple symmetry index (RSI), continuity index (CI), bifurcation index (BI), straightness index (SI), and two different parallelism indices (PI1 and PI2).In general, RI = 15 or less indicates wave or water current origin; RI = 17 or more indicates wind or swash origin. RSI = 1.5 or less indicates wave or swash types; RSI = 3 or more indicates wind or water current types. CI = 15 or more suggests wind or wave origin; CI = 10 or less suggests water current origin. BI = 10 or more suggests wave varieties; BI = 1 or less suggests wind varieties. SI = 102 or more indicates wind or deep-water wave types; SI = 15 to 102 indicates wind or wave types; SI =4 or less indicates current types. PI1 = 7 or more suggests wave origin; PI1 = 1 or less suggests water current origin. PI2 = 0.4 or more is probably the result of swash or water current action. PI2 = 0.2 or less is probably the result of wind or wave action. Longitudinal ripple marks (such as rib-and-furrow) and deformed or modified varieties (such as flat-topped tidal-flat ripple marks and nearly- flat-topped intermittent creek ripple marks) have been excluded, inasmuch as (1)they are commonly easy to identify from their appearance, and (2)they are difficult to measure with ordinary methods.Plots of two indices against each other on coordinate paper can be particularly useful; the best combinations are RI vs. RSI, and RI vs. PI1, although several other pairs are almost as good. Where all seven parameters can be obtained, the confidence one can have in the interpretation is close to 98%.The effects of current bias, or depth bias, on wave-type ripple marks, extend to both the symmetry (RSI) and to sediment-transport interpretations. Unless the investigator is reasonably sure that no such bias is present (i.e., RSI = 1.0 instead of some significantly higher value such as 1.5), wave-type ripple marks cannot be used to determine direction of either wave approach or sediment transport. If no such bias is present, wave-type ripple marks still cannot be used to determine precise sediment transport direction. If RSI = 1.0 precisely, it is not even necessary that the ripple crests parallel the waves that formed them. The same restrictions apply to the interpretation of micro-crossbedding (that is, ripple mark internal structure). Despite these seemingly severe limitations, general geometry commonly permits a reliable interpretation, and hence ripple marks can provide a great deal of useful data for paleogeographic interpretations.The swash-zone variety of ripple marks includes two sub-types: those modified by a small but unmistakeable hydraulic jump, and those not so modified. The RI can be used to distinguish between these two, even when they were not observed to form.

Notizen: The significance of recent studies on the argillaceous rocks in the interpretation of sedimentary facies (including the red beds) Attapulgite and sepiolite are clay minerals, neoformed in the alkaline chemical facies. The ions, Si, Al, Mg, which are necessary for authigenesis, are leached from the continent under humid tropical conditions. Lateritic profiles originate only on the continents. If erosion begins again, the siderolithic facies, which contains a great proportion of inherited kaolinite, succeeds the alkaline chemical facies. These two facies are mutually connected in space and time.The “red-sandstone” facies consists of a reworking of altered rubidied sands, which originate in warm climates with alternating humid and dry seasons. It is the maintenance of erosion by living tectonics which determines the intensity of the alteration. The “bituminous-coal” facies corresponds to conditions which are analagous to the previous periods, but more humid, with more intense subsidence and a higher general base level of erosion. Bituminous-coal facies and red-sandstone facies are characterized by the predominance of illite and are connected in time.In the geochemical cycle, detrital argillaceous series succeed the carbonated and saliferous facies. Under certain conditions, these chemical facies indue a positive transformation, i.e., aggradation under the influence of the confined environment.Thus, the detrital, transformed or neoformed clay minerals can be used as palaeogeographical or palaeoclimatical indicators

Notizen: The paper describes tests made on a small river to examine the practicability of measuring quantitatively, by tracer methods, sand transport occurring over a rippled bed in a natural channel. Three principal tracer methods, all previously verified under steady flow conditions in a laboratory channel, and identified as the spatial integration, time integration and steady dilution methods, were examined by introducing radioactive and fluorescent tracers to represent a narrow size fraction of the bed sand. The serious limitations of the time integration and steady dilution methods under conditions of unsteady solids discharge were exposed by a sudden flood discharge occurring during the course of the study. An approximate method, based on the time integration approach, but also requiring some spatial tracer data, is suggested, whereby an estimate of the transport is possible in the case of highly variable sand discharge. However, it is seen that in the sand case, the spatial integration method offers the most workable and informative tracer method for use in natural rivers. The results, by this method, were generally consistent with those given by the summation of the measured suspended-solids flux and the transport occurring either by surface creep or in close vicinity to the bed. The latter quantity is determined from the downstream advance of the ripple bed-forms, and methods are described for its derivation from ultrasonic echo sounder records of bed profiles. Finally sand transport values are calculated for a number of river discharges and for two laboratory channel tests using various well-known computational procedures—Einstein, Bagnold, modified Einstein, Meyer-Peter and Muller, and Laursen procedures. Significant differences in the computed values for individual flow conditions are observed.

Notizen: Few examples are given to demonstrate that crushing of hard sedimentary rocks practically does not break up the heavy minerals present in the rock. Also the ratios of the various minerals mostly are not changed.

Notizen: The type Lindsey Bridge Member of the Moorefield Formation of northeastern Oklahoma consists of 24 ft. of massively cross-bedded limestone. Cross-bed shape, lithologic variation, grain size and sorting, distribution of insolubles, and distribution of fossils and fossil burrows can be explained with reference to a hydrodynamic model developed in recent flume studies.Three facies can be distinguished in this unit: (1 Thei) foresets, thick-bedded, well-sorted, fine to medium crinoidal grainstones, dipping at angles up to 1° (2) toesets, which are thin-bedded, poorly sorted, skeletal packstones notably more fossiliferous than the foresets, with which they are laterally gradational; toesets dip at approximately 5°-8° (3) bottomsets, composed of argillaceous, fine-grained (mainly silt-size), skeletal limestones. Foresets overlie previously deposited bottomsets; this geometry is typical of regressive sedimentation.The exposure is adjacent to a pre-Moorefield topographic high. As currents crossing this high entered a basin on the downcurrent side, flow separation occurred. Bed material load was deposited mainly on the foreset slope, suspension material mainly in toeset and bottomset areas. The poor sorting of the toesets is in part due to reverse circulation, formed by the flow separation, which transported bottomset sediment back toward the foreset. Jopling (1965b) has shown that this depositional geometry produces tangential cross-beds similar to those seen in this outcrop. Differential settling velocity, substrate stability, and abundance of organic detritus influenced other sedimentologic properties of the deposit.