ALBERT

Notes: For horizontal layering and plane horizontal impulsive wavefronts it is theoretically possible to get rid of multiple reflections by a feedback procedure which can easily be derived using raypath philosophy. To reduce the increase of noise inherent in the method the precise theoretical formulae are altered in such a manner that a practical application becomes possible. For this purpose the autocorrelation will be used.Application of the new process to a CRP section where the shot geophone distances in the field had not been long enough to attenuate multiple reflections effectively gave favourable results.

Notes: Two in situ measurements of stress wave velocity in a granodiorite massif were made. Firstly, the velocities close to the source were investigated (for elimination of the influence of cracks), and secondly, the velocities in different horizontal directions over a large area were studied from the viewpoint of their dependence on the crack system of the medium. A correlation between the mutual orientation of the cracks and the maximum or minimum values of the stress wave velocities was obtained.

Notes: The technique of linear digital filtering as developed for the direct interpretation of Schlumberger and Wenner soundings (Ghosh 1971) has been applied here for the derivation of the resistivity transform function from the field dipole measurements as the first step in directly interpreting dipole data. Filter coefficients for this transformation have been worked out for the radial-polar, perpendicular and parallel (30°) arrays of dipole sounding. The procedure combines speed with accuracy.

Notes: Dipole soundings are more sensitive to noise caused by lateral and superficial inhomogeneities than Schlumberger soundings. However, the former are preferable for deep explorations in view of the relatively short cables required. The simple solution of carrying out the field work by means of dipole spreads, and to transform the dipole resistivity diagrams into Schlumberger ones by means of proper formulae would be valid only for smooth and regular curves; but often, owing to the presence of lateral noises, the dipole data show a considerable scatter. For such cases a “continuous dipole sounding” method is proposed for which all successive dipoles are contiguous, so that all parts of the profiles are covered and interpolation is not necessary. Obviously the moving dipoles have lengths proportional to their distances, so that they appear equal in the usual bilogarithmic scale. It follows that only polar-dipole arrays may be used. The transition from a dipole to the corresponding Schlumberger apparent resistivity diagram requires an integration constant which is not unequivocally determined. Therefore, the solution is not unique, but all possible derived Schlumberger diagrams have a common part. Similarly, they have some common interpretative results, which may be referred to the original dipole diagram obtained in the field.A special measurement technique is required since the dipole-dipole voltages to be determined are noticeably smaller than the Schlumberger ones. This is true also because dipole soundings are used for great depths and for long distances between the two dipoles.

Notes: Basic requirements for a seismic reflection system using a moderate-power controlled source are discussed. General considerations and computer modelling show promise for geophysical prospecting, especially at low penetration and very high noise level. For many applications, ranging from mineral and water prospecting, to civil and military engineering, and even archeology, a relatively cheap, small and portable device of this kind might be more convenient than conventional explosive sources or sophisticated controlled sources of the vibroseis type. The use of a simple, low frequency periodic signal facilitates rapid data processing procedures and suggests that the mechanical generator will be very simple and cheap.

Notes: A method is described to transform a dipole sounding curve, obtained with any one of the common dipole arrays over a horizontally layered earth, to the form of a Schlumberger sounding curve. Starting from the general expression which relates the dipole apparent resistivity to the Schlumberger apparent resistivity and its derivative with respect to the spacing, it is possible with some approximations to derive an easy numerical computation procedure in order to perform the transformation. The applicability of the method is discussed briefly.

Notes: Approximate deconvolution by means of Wiener filters has become standard practice in seismic data-processing. It is well-known that addition of a certain percentage of noise energy to the autocorrelation of the signal wavelet leads to a filter that does not increase, or even reduces, the noise level on the seismogram. This noise addition will, in general, cause a minimum phase signal to become mixed phase. A technique is presented for the calculation of the optimum-lag shaping filter for a contaminated signal wavelet. The advantages of this method over the more conventional approach are that it needs less arithmetic operations and that it automatically gives the filter with the optimum combination of shaping performance and noise reduction.

Notes: A set of parabolae is defined to approximate the observed gravity profile for specifying the lateral density variation in a two dimensional causative body. This variation separates the “biased” as well as “unbiased” residual anomaly structure. The method may be directly incorporated into existing numerical and graphical techniques of interpretation for subsequent delineation of structural configuration. The simple relations derived by inspection of the observed gravity profile permit universal application of the technique and in particular for the determination of the size and shape of sub-shelf structures. The suitability of the method in various problems of two dimensional interpretation has been indicated through an illustration of the Godavari Basin (India).

Notes: Decomposition of IP discharge curve into a sum of exponentials yields more information than present practice does. Such a work was performed, as a beginning, by hand, plotting the ordinates on semi logarithimic paper. It gave, according to the cases, two or three exponentials, each with an amplitude Ai and the time constant τi.Three examples of ground prospection are given, the third of which shows an anomaly, unnoticed with present technique but obvious on a profile curve with A1/A2 in ordinates.A computer processing technique is described which yields directly the time constants τi by seeking a differential equation which the IP voltage satisfies; the order of the equation is set arbitrarily. On a practical prospection record with only two exponentials, the assumption that the differential equation does not depend on charge duration (everything else being equal) has been checked (the shape of the curves would depend on boundary conditions). The assumption roughly holds for charge durations from 5 seconds to 40 seconds. We hope that a larger number of exponentials will yield better results.〈section xml:id="abs1-2"〉〈title type="main"〉SommaireLa décomposition de la courbe de décharge en une somme d'exponentielles permet d'en tirer plus d'information que la pratique actuelle. Un tel travail a été fait, pour commencer, à la main en portant les ordonnées sur papier logarithmique; il a fourni, suivant les cas, deux ou trois exponentielles avec, pour chacune d'elles, le coefficient Ai et la constante de temps τi.On donne trois exemples de prospection sur le terrain, dont le dernier comporte une anomalie, inaperçue avec la technique actuelle, mais bien mise en évidence en traçant la courbe de A1/A2 le long du profil.On donne ensuite une technique de calcul sur ordinateur des τi, en recherchant l'équation différentielle à laquelle obéit la tension ΔVPP enregistrée, l'ordre de cette équation étant fixé arbitrairement. On a cherchéà vérifier sur un enregistrement de terrain, avec. deux exponentielles seulement, l'hypothèse suivant laquelle l'équation différentielle ne dépend pas de la durée de charge (toutes choses égales d'ailleurs). L'hypothèse se trouve grossièrement vérifiée pour les durées de charge allant de 5 secondes à 40 secondes, et nous espérons qu'un plus grand nombre d'exponentielles donnera de meilleurs résultats.

Notes: The conventional seismic technique is subject to a recording time following each transmission of energy, in which it is forbidden to release any new pulse. The recording time depends on the deepest reflection of interest, and is often 10 seconds or more in actual practice. To each transmission corresponds one record, i.e. a fixed amount of data which cannot be increased in a given time.Pulse coding allows us to go beyond this limit, by transmitting several times during the normal recording time. The procedure gives as many records as there are pulses, but they overlap, each event being repeated every time there is a pulse. It is possible to process the composite record back to its usual appearance with all events in their proper place if the time breaks are accurately known and make up a code such that the unavoidable noise generated by the process be kept, on the final section, below the ambient noise. The processing is quite similar to that of records made from vibrating sources, though faster in practice.The additional information can be devoted to a saving of time and money as the same profile may be recorded in a shorter time; or to an improvement of quality of the section due to a higher order of coverage, a multiplication of the ray paths and a closer sampling of the reflectors. It is also possible to record information in several planes at the same time, and to work out a 3-dimensional restitution, without loss of production.The process applies to all kinds of sources provided they can be triggered according to the code with sufficient accuracy. Depending on the source and conditions of implementation, the method benefits from other advantages such as better resolution, increased flexibility, and better coupling.Two different names have been given to the process, Sosie and Seiscode, which apply to slightly different parameters for the sequence of pulses. Sosie is more useful at sea, while the normal scope for Seiscode is onshore. Both names are trademarks for SNPA.

Notes: Two-layer type curves of apparent frequency effect for the Wenner configuration are presented. The formulation is based on the normal definition of frequency effect in terms of resistivities measured at different frequencies plus the definition of apparent resistivity over two horizontal layers as a function of first and second layer resistivities. The use of these type curves in the interpretation of multilayer apparent frequency-effect curves is described and some field examples are given.

Notes: In this paper properties of the discrete zero-phase time function are derived and compared with related properties of the discrete minimum-phase time function.The two-sided minimum-length signal is introduced and it is derived that, for any given amplitude spectrum, the two-sided minimum-length signal and the signal with zero-phase spectrum are identical signals. A comparison is made between the one-sided minimum-length signal (minimum-phase signal) and the two-sided minimum-length signal (zero-phase signal).A computational scheme is discussed which determines the zero-phase correspondent of a given signal.A method is proposed to compute zero-phase least-square inverse filters. The efficiency of minimum-phase and zero-phase least-square inverse filters is shown on signals with different phase properties.A criterion is derived which determines whether a symmetric time function has the zero-phase property. The close relationship with the minimum-phase criterion is discussed.Finally the relationship between signal length and resolving power is illustrated on numerical examples.

Notes: Empirical equalities derived from time domain induced polarization scale modelling with the gradient array over simple geometries, and from the potential field functions for equivalent simple charge configurations are similar. The function for the dyke like body is analogous to the magnetic case allowing both total and vertical magnetic field interpretation techniques to be applied to gradient array chargeability anomalies.

Notes: A checking method of digital multiple elimination and of deconvolution processing using computers and based on optical autocorrelation is first presented. Comparison between autocorrelograms before and after a single or several processing steps allows to estimate, on one hand, the strength of the deconvolution obtained, known by the study of the central parts which is in fact the signal autocorrelation, on the other hand, the multiple elimination given by the study of side parts of the autocorrelogram.Further, an optical deconvolution procedure, is presented. For this, it is supposed that the signal is known and optically reproduced in the same way as the one of a trace. This is achieved by sphero-cylindrical optics allowing trace to trace processing. Deconvolution is carried out in the spectral domain by inserting a filter in the Fourier plane of the optical unit, the transmission law of which expresses the Fourier transform of the antisignal. This filter device introduces a holographic technique called Fourier holography, in such a way phases as well as amplitudes are preserved.Several results are presented from a synthetic section and also from field sections.

Notes: The separation of regional from local gravity anomalies by means of the application of two-dimensional linear filters is analyzed. It was found that optimization of the filter in the least squares sense leads to filters that produce strong localized concentrations of the error, which may erroneously be interpreted as anomalies. For this reason the maximum absolute value of the error is a more important criterion for the quality of the filter than the root mean square error. This maximum absolute error is minimized by the minimax filter. Intermediate filters are derived which give a transition zone which comes appreciably closer to that of the optimal filter at only a small price in terms of increase of the maximum absolute error.

Notes: Cable feathering is defined as the angle between a line connecting the cable end points and the line of the seismic profile. It is shown that an average reflection point map is more accurate than a shot point location map for geologic interpretation. Geologic resolution is degraded by feathering and this degradation is a function of the number of channels recorded. Feathering in areas of dipping reflectors produces non-standard normal move-out because the depth points are not common, and the perpendicular distances to the reflecting surfaces vary among traces in the c.d.p. gather. An example of a profile shot across a large river is discussed.

Notes: First, we review briefly the principle of the method, the computation of theoretical curves for a layered earth, and the recording technique in use in our surveys.The case history deals with an area covered with overthrust nappes (marls of Miocene age), which had slid on a Triassic sole, obscuring the geological picture.The magnetotelluric survey followed those of gravity and aeromagnetics and preceded the seismic one from North to South, it displayed a shallow and gently dipping basin, a major fault system, and a deep basin with a thick resistive layer, often underlying a conducting one.The seismics, and later the drilling of a well East of the profile, confirmed these features; in particular, the thick resistive layer was revealed to be Jurassic; only its thickness had been slightly overestimated. This fact lead the people in charge of the operations to ask for a reinterpretation synthesis of magnetotellurics, seismics and gravity, the results of which are also presented.

Notes: Qureshi and Mula have suggested a computer method for the calculation of the shape of a two dimensional body from the gravity anomaly profile associated with it. The application of the method, however, was restricted to those bodies which have their top or base horizontal and end sides vertical. In this paper study has been made to investigate the possibility of eliminating the above mentioned restrictions and has arrived at the affirmative conclusion.

Notes: Consideration is given to the form of apparent resistivity sections obtained by varying electrode array position and spacing over two dimensional features.Since basic solutions exist for horizontally layered media and for vertical or dipping single interfaces, simple rules are proposed whereby these solutions can be directly combined to give solutions for more complex sections. Substantial approximations may be involved as the rules do not fully allow for interactions between the constituents.The range of error incurred in application of the rules is explored, with particular reference to the square array system of resistivity measurement. The two extremes- of orientation of the square array with respect to the line of section are separately considered in this survey.Within appropriate limits, the rules appear extendable to a wide variety of simple structures for which rigorous solutions would be formidable. The rules are finally discussed in relation to practical applications.

Notes: In modern oil exploration layers of prospective interest with rather simple structural features are often overlain by very complicated bodies as e.g. saltdomes or other kinds of diapirs, olistostromes, or front zones of overthrusted blankets. In all these cases normal reflection seismic investigations, where downgoing and upgoing rays are rather close to each other, mostly fail, either because no reflections from underneath the complicated bodies are obtained, or because a reliable migrated depth presentation becomes practically impossible due to the inhomogeneity of the overlying bodies.The undershooting technique avoids these difficulties by using ray paths which do not traverse the complicated bodies e.g. by shooting on one side of a saltdome and recording on the other side. On account of the large shot-geophone distances in this method special considerations and computer processes were developed concerning moveout corrections for common depth point stacking and migrated depth presentation.In many cases the location of the disturbing complicated bodies is known in advance. The shooting and recording program can then be adjusted to this knowledge and thereby kept to a minimum. If the location of the complicated bodies is unknown a more extended seismic program has to be carried out encompassing a great variety of shot-geophone distances. But in this case the approximate location of the complicated bodies can be deduced from the survey too.Results are presented in order to give an idea of the efficiency of the new seismic tool.

Notes: This paper describes the procedure for interpreting the apparent resistivity data measured with the two-electrode array directly with the help of kernel function. The calculation of kernel function from the observed resistivity curve is done by the method of decomposition. In the method of decomposition the resistivity curve is approximated by a sum of certain functions, whose choice is only restricted by the requirement that the contribution to the kernel function corresponding to them should be easily computable. A few such functions are classified. These, and the standard curves for corresponding kernel functions obtained by utilising an integral expression for two-electrode array expressing the kernel explicitly in terms of the apparent resistivity functions, are plotted on log-log scale. The determination of layer parameters, that is, the layer resistivities and thicknesses from the kernel function can be carried out by a method proposed by Pekeris (1940).

Notes: A six-channel wide-band digital system for magnetotelluric measurements is described The system is designed to operate in the frequency band 10-.0001 Hz. The recording is made on a 7 track tape in an IBM compatible 12 bit format. The amplitude and phase responses of the system and sample records are presented.

Notes: Several types of multichannel filters have been introduced in the past with the purpose of rejecting, in a seismic section, coherent noise having a slope different from that of the signal.These filters, generally, tend to introduce a certain amount of mixing and therefore the output trace shows increased horizontal coherence. This is due to the model on which these filters are based, since the hypothesis is posed that the reflectors are continuous. This may be dangerous since it could lead to mistaken interpretations, for example when small faults or breaks are made to disappear in the output section.Other problems that could arise in the application of multichannel filters after-stack are space-aliasing and high-pass filtering. The former occurs when coherent noise is rejected with apparent Velocity V and frequency fa=V/X, where X is the distance between traces. In this case, the signal also is distorted since it is rejected in the same frequency range. The high pass filtering effect occurs when the multichannel filter is designed to remove low coherent noise with high apparent velocity.In the paper a family of multichannel filters is presented based on a model of the seismic section such that minimum mixing effects appear. The filters are designed to give good results even in the case of low frequency and high velocity coherent noise.Some practical examples are shown.

Notes: Sub-bottom profilers achieve high resolution but limited penetration beneath the seabed. Marine seismic surveys with long streamers and conventional sources suffer from an incomplete CDP stack and an unnecessarily low signal frequency in the early part of the section. Consequently there is a depth interval over which the optimum resolution of the seismic reflection method is not achieved. This paper describes the design, conduct, and results of an experimental survey made to obtain high resolution sections (predominant frequency about 200 Hz) with reflection times up to one second in the northern North Sea. The prime motivation for the experiment was to assess the possibility of mapping a shallow gas sand which had been encountered by the drillers.The design concept of the survey was to keep all the benefits of conventional marine seismic data gathering and processing, but to reduce their dimensions and time scales by a factor of five to ten. The survey in 1972 recorded a total of twenty-four lines using twenty-four fold cover with 5 m spacing between the reflector points, and a separation of 50 m between adjacent lines. Multi-electrode sparkers were used with a shallow purpose-built twenty-four channel 240 m hydrophone streamer. The recording sample interval was 1 ms. The final sections, obtained after conventional data processing, were of good quality. The results of velocity analysis helped to distinguish primary and multiple energy. Reflections with large negative reflection coefficients were seen in some parts of the survey area, and these are thought to indicate thin gas sands.

Notes: This paper deals with a case study on the application of auto-correlation and spectral analysis methods to mineral assay data taken along seven drives and two winzes concerning the McTaggart's (West) lode of Kolar gold fields. The general model conceived in this study is: measured (estimated) ore grade at jth location =true value + error at jth location. Employing an auto-correlation function of the form C e- a |k| for signals, the respective contributions of signals and noise to the total logarithmic variances for the data along drives and winzes are analysed. Smoothed spectral density estimates and their 90% confidence limits are computed for the series of data.

Notes: Methods and typical case histories of EM and IP surveys are compared in order to check their compatibility for the investigation of large areas for base metal sulphides. It is demonstrated that the fast, low cost EM may miss sulphide concentrations which cause no reduction of apparent resistivity, or which act like horizontal slabs, where EM anomalies occur marginally. In such cases only IP can recognize the whole extent of the mineralization. The misleading role of graphite exists for both methods.The conclusion is that EM remains the only economical method to survey whole ore districts, but that the shortcomings should always be taken into account in the interpretation. They can be overcome by employing geological, geochemical or other geophysical indicators in selecting promising targets for follow-up IP. Even if less than 20% of the area is covered by the expensive IP, there is a fair chance that all sulphide bearing rocks will be found. Therefore, the question is not whether to apply EM or IP methods, but how to combine them best.

Notes: The paper deals with the prerequisites of application, specific peculiarities and methods of electrometric and thermometric investigations aimed at the solution of certain engineering-geological problems in offshore areas. Practical examples are supplied.

Notes: The voltage induced in a horizontal loop on a layered ground has been calculated for the case where the loop is excited by a step current and measurements are made during the off-cycle.The expressions derived for a uniform ground show that for large time t the induced voltage E(t) is approximately given by E(t)≃— (Ibαμ/20t) (σμ2/t)3/2 where σ is the conductivity of the ground, μ the permeability, b the loop radius, and I the amplitude of the current step. For small times the corresponding result is E(t)≃—Ibμ/2t.When the ground is composed of a number of layers a numerical procedure for calculating the induced voltage is described.The calculated responses of various multilayered structures show that at short times the induced voltage is asymptotic to that produced in the case of a uniform ground of conductivity equal to the top layer.Interference effects in the top layer can lead to anomalous decay curves which may result in the underestimation of the conductivity of a buried layer.

Notes: Marine geophysical work requires accurate navigation on a continuous basis. A repeatability of 150 m CEP (circular error probable) with sequential positioning of 15 m CEP is usually acceptable. Quoted figures for many presently available navigation systems yield nearly the required accuracy. In actual operations, however, such accuracies may not be achieved, and usually the performance actually realized cannot be determined for want of independent measurements for comparison. If more redundancy in navigation measurements were available on an integrated basis, the limitations of individual systems would no longer be so critical and the accuracy of measurements could be assessed in real time. Failures in navigation continue to occur. Such failures usually result from ignorance of the capabilities of the navigation system and limitations and consequent choice of a system which is not appropriate to the demands of a particular survey. The points to be covered in work standards are listed.

Notes: The acceptance of articles in Geophysical Prospecting is strictly based on the originality and relevance of the contents. In order to be published a paper has to satisfy additional requirements on its external form and on its style and language: it should be written preferably in English though articles in French and German are permitted. A paper should consist of (i) a title page, (ii) an abstract, (iii) the text, (iv) list of references, (v) captions to illustrations, if any, (vi) tables, if any, and (vii) illustrations, if any. These seven parts should be mailed together but be physically separable and should be prepared according to rules which are either based on printing necessities or on the editorial style of the Journal.Failure to comply with these rules may result in delay in further processing of the article. Since Geophysical Prospecting is edited with a minimal budget correspondence with authors is kept to a minimum.

Notes: Depths of investigation for normal (bipolar) and focusing (unipolar) linear electrode arrays have been computed following the method given earlier (Roy and Apparao 1971) both in homogeneous and layered earth. The focusing arrangement is found to be superior to normal arrangement both in regard to depth of investigation and zone of uniform depth of investigation. This analysis holds good in layered media too. Further, the depth of investigation increases with the increase in the length (2M) of the electrode and reaches a limit, 0.29L for normal and 0.50L for focusing, when the electrode attains an optimum length to satisfy the infinite condition. This optimum length of the electrode is six times the distance L of the observation point from the electrode for normal and about ten times for focusing. A contour diagram for contributions of individual ground elements to the total signal measured at the centre of focused system is also discussed.

Notes: The authors generalize a method expounded in a previous paper (1971, Geoph. Prosp. 18, 786-799) to the case of a local conductivity σ(M) of the infinite medium satisfying the relation 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:00168025:GPR246:GPR_246_mu1"/〉 where the Ri's are the distances from the point M to n fixed points Si (i= 1,. n), k is a positive real constant and Ci, Cii are constants ensuring the condition α 〉 O.The sub-surface conductivity distributions (half-spaces) complying with (1) provide a wide variety of conducting structures, which can fit quite successfully the rather complicated distributions of conductivity occurring in natural ore bodies.An exact algebraic calculation of the apparent resistivity for these grounds, valid for any dc electrical prospecting devices (Wenner, Schlumberger, dipole, etc.) leads to a set of simultaneous linear equations, with a matrix which is invariant with respect to the position of the quadrupole being used. This greatly simplifies the numerical computation.We also present some examples of cross sections for the real and apparent resistivity obtained by this method.

Notes: Section migration after stack has been widely accepted by the industry. From a theoretical point of view, section migration before stack should provide superior results, the improvement warranting the drastically increased cost is not realized in most cases.There are a number of reasons that explain the discrepancy between actual and theoretically expected quality: Long period statics, refraction of rays, two-dimensional treatment of an actually three-dimensional problem.The section migration package subject to this paper allows(i) to take refraction into account,(ii) to discriminate against noise with a variety of statistical and geometrical criteria,(iii) to adapt processing time to problem complexity by a special process called SEMI-STACK.A number of examples will demonstrate the effects of section migration.

Notes: A seismic trace after application of suitable amplitude recovery may be treated as a stationary time-series. Such a trace, or a portion of it, is modelled by the expression 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:00168025:GPR627:GPR_627_mu1"/〉 where j represents trace number on the record, t is time, αj is a time delay, α (t) is the seismic wavelet, s(t) is the reflection impulse response of the ground and nj is uncorrelated noise. With the common assumption that s(t) is white, random, and stationary, estimates of the energy spectrum (or auto-correlation function) of the pulse α(t) are obtained by statistical analysis of the multitrace record. The time-domain pulse itself is then reconstituted under the assumption of minimum-phase. Three techniques for obtaining the phase spectrum have been evaluated: (A) use of the Hilbert transform, (B) Use of the z-transform, (C) a fast method based on inverting the least-squares inverse of the wavelets, i.e. inverting the normal time-domain deconvolution operator. Problems associated with these three methods are most acute when the z-transform of α(t) has zeroes on or near the unit circle. Such zeroes result from oversampling or from highly resonant wavelets. The behaviour of the three methods when the energy spectra are perturbed by measurement errors is studied. It is concluded that method (A) is the best of the three. Examples of reconstituted pulses are given which illustrate the variability from trace-to-trace, from shot-to-shot, and from one shot-point medium to another. There is reasonable agreement between the minimum-phase pulses obtained by this statistical analysis of operational records and those estimated from measurements close to the source. However, this comparison incorporates a “fudge-factor” since an allowance for absorption has to be made in order to attenuate the high frequencies present in the pulse measured close to the shot.

Notes: The implementation of a stacking filter involves the filtering of each trace with an individual filter and the subsequent summing of all outputs. The actual position of a trace in space as well as certain simultaneous shifts of traces and filter components in time do not influence the process. The resulting output is consequently invariant to various arbitrary coordinate transformations. For a certain useful class of ensembles of non-linear moveout arrival times for signals a particular transformation can be found which transforms a given ensemble into one consisting only of straight lines. It is thus possible to reduce, for instance, the analysis of a stacking filter designed for hyperbola-like moveout curves to the analysis of a velocity filter with linear moveout curves. As the (f—k) transform is a very useful concept to describe a velocity filter, it can consequently be applied to characterize a stacking filter in regard to its performance on input signals with non-linear moveout.

Notes: The technique of linear digital filtering developed for the computation of standard curves for conventional resistivity and electromagnetic depth soundings is applied to the determination of filter coefficients for the computation of dipole curves from the resistivity transform function by convolution. In designing the filter function from which the coefficients are derived, a sampling interval shorter than the one used in the earlier work on resistivity sounding is found to be necessary. The performance of the filter sets is tested and found to be highly accurate. The method is also simple and very fast in application.

Notes: A case history is presented for the exploration of barite with the electrical resistivity method. Altogether eight locations were recommended out of which six correspond to barite bodies. In the present case the gravity method, which is commonly used for the location of barite because of its high density contrast with the host rocks, has failed, perhaps due to small size of the ore bodies.

Notes: A correct derivation of rms, average and interval velocities from one another and from common depth point stacking velocities requires a clear understanding of the relationships between these velocities. We relate the average velocity to the rms velocity through a “heterogeneity factor” which is a quantity that gives a measure of the degree of velocity heterogeneity in the ground. The interval velocity is a quantity which varies according to the method of its derivation. The difference between rms and stacking velocities depends on the heterogeneity factor and on the length of the spread. Unless allowed for, this difference can reverse the advantages of long spreads and cause large errors in interval velocity determinations. It may be removed through a number of techniques. The accuracy of stacking velocities in the presence of random “noise” is independent of the heterogeneity factor. Relevant expressions can be broken down into simple formulae which give the accuracy quickly and with good precision.

Notes: Results obtained from a linear programming ground-water management model are tested against those obtained using numerical and electrical analog ground-water models. The optimal distributions of pumping and head as predicted by the management model are verified.An improved optimal solution could be obtained by reformulating the management model using different constraints or a finer grid spacing.

Notes: DuPage County, one of the major counties of the Chicago metropolitan area, obtains all of its water supply from ground-water resources. In 1972, pumpage was 56.6 mgd, 18 percent more than the combined potential yield of shallow aquifers and the practical sustained yield of deep aquifers. Total pumpage from shallow aquifers almost equals the potential yield. In some areas, yields of shallow wells have declined drastically as a result of excessively heavy pumpage. Pumpage from deep aquifers is more than double the practical sustained yield. Demands for water are projected to increase more than 250 percent by the year 2020. Alternative methods of developing supplies to meet the anticipated demands include artificial recharge of shallow and/or deep aquifers, mining of deep aquifers, increased diversion of water from Lake Michigan, demineralizing Mt. Simon sandstone water, and importation of underdeveloped surface or ground-water resources in north central and northwestern Illinois. Increased coordination of development programs becomes of greater importance as locally available supplies lose the capability to meet growing demands.

Notes: The alluvial aquifer underlying and adjacent to the Mojave River near Barstow, California, has been subjected to degradation from percolation of industrial and municipal wastes for more than 60 years. Effluents discharged to the aquifer have contained high concentrations of both organic (detergents, oil and grease, phenols, humic compounds, and others) and inorganic (chromium, chloride, phosphates, and others) substances. The concentration of dissolved organic carbon (DOC), as determined by a wet combustion technique, has been shown to be a definitive parameter in identifying ground water affected by waste disposal. DOC concentrations ranged from 0.1 to 0.8 milligram per liter in the nondegraded ground water and exceeded 6 milligrams per liter in the ground water affected by the waste discharge.The general distribution of DOC in the degraded ground water has been defined both areally and vertically. The vertical distribution of DOC and other constituents indicates that two plumes of degraded water occur at different depths. A comparison of the areal distribution of DOC and detergents (as MBAS) suggests that some organic compounds may have been adsorbed by the aquifer sediments.

Notes: Analytical data for 161 sampling sites indicate orthophosphate concentrations in ground water ranging from 0 to 1.7 mg/1. Ground water in about 50 percent of the county contains concentrations of 0.1 mg/1 or greater. In two areas aggregating 115 square miles, orthophosphate concentrations exceed 0.5 mg/1. Principal sources of phosphate in ground water in Hall County include: indigenous soil phosphate, municipal sewage effluent, commercial fertilizer, and feedlot wastes.

Notes: In areas of crystalline and basaltic rocks in India dug wells of large diameter may offer the only opportunity to test for the hydrologic characteristics of the shallow aquifers. Analysis of aquifer tests in these wells is difficult, however, if the volume of water stored in the wells contributes significantly to their discharge during the tests. In most dug wells, the time rate and spatial distribution of drawdowns in the aquifer, and the rate of change of head in the dug well are not predictable by the Theis equation or its semilog modifications. High rates of pumping result in difficulties due to the insensitivity of head distributions to drawdowns in the well.A review of current methods of analysis of aquifer tests in large-diameter wells indicates that most have serious theoretical and practical deficiencies. It is concluded that the methods of Papadopulos and Cooper (1967) and Papadopulos (1967) are the best available approaches, providing measurements of well volume can be made with sufficient accuracy. A consideration of aquifer tests in fractured rocks suggests that these tests can probably best be handled by treating the aquifer as an anisotropic porous medium on a macroscopic scale and utilizing observation wells.

Notes: To aid in determining the direction of ground-water flow after the effluent from the Lake George Village sewage treatment plant is discharged onto natural delta sand beds, resistivity studies were made in the soil (sand) in the vicinity of the recharge beds. Ground water having high dissolved solids is identified as producing lower resistivity readings. The sewage effluent has a higher dissolved solids content than the existing ground water in the area. The path of the recharged sewage effluent, as identified by lower resistivity readings, appears to flow in a northerly direction from the sewage treatment plant along Gage Road toward West Brook. Due to interferences, the resistivity studies could not show whether the high conductivity ground water flows into or under West Brook.

Notes: Practically all of the toxic chemical land disposal sites now in operation are equipped with only minimal and generally ineffectual monitoring systems, which seldom are capable of detecting even excessive surface-water and ground-water pollution from such sites. From monitoring data normally obtained, it is practically impossible to quantitatively evaluate the total toxic chemical buildup in contiguous soil, plant, and water environments or the vertical and horizontal migration patterns of pollutants through underlying earth materials. Monitoring facilities and procedures described in this paper are designed to provide that data required to effectively evaluate all of these parameters. These evaluations in turn should be most helpful in selecting the safest possible sites for hazardous waste disposal, and in developing ways and means to design, operate, and monitor such facilities that will assure minimal danger to public health from this particular waste disposal practice in the future.

Notes: Aquifers may serve as storage reservoirs, as treatment mediums, as discharge conduits, or in some combination of the various uses. If an aquifer serves as a conduit, the Darcy equation gives an accurate and simple solution for discharge provided the conduit is uniform; if nonuniform, the accuracy may be very poor unless special care is taken.Differential equations based on Darcy's equation and the equation of continuity give the steady-flow discharge rate for confined aquifers in which the cross-sectional area and permeability vary from point to point. For the general case the derived discharge expression is theoretically exact, whereas, for specific cases an approximate form can be used depending on the boundary conditions. Integration of the approximate form for a given aquifer length yields simplified solutions for discharge where the variation in cross-sectional area and/or permeability with distance in the direction of flow can be described by some mathematical expression.

Notes: Contemporary use patterns of land and water resources create conflicts between natural and human environments. These conflicts are generally not discussed as part of a classical approach to geologic education. This paper addresses the need to increase non-earth science training simultaneous with traditional training. The benefits to be gained will be welcomed by both students and their potential employers. One approach to suggested interdisciplinary water-resource education is discussed.

Notes: Low-rate or irrigation-type systems for land application of sewage effluent or similar wastewater are often used in humid areas because they have a small impact on the underlying ground water. In arid areas, low-rate systems cannot be used to produce renovated water for ground-water recharge, because the renovated water will have a much higher salt content than the effluent. Renovated water of relatively low salt content can only be produced with high-rate systems. Such systems, which require permeable soil, can also be used in humid areas to reduce the land requirements. To minimize the impact of high-rate systems on ground-water quality, the system should be managed to remove as much of the pollutants (particularly nitrogen and phosphorus) as possible from the wastewater as it seeps through the soil, and to restrict the spread of renovated wastewater in the ground-water basin. Nitrogen removal can be maximized by stimulating denitrification in the soil. Certain soils can store large quantities of phosphate. The spread of renovated water in the ground water can be controlled by intercepting the flow of renovated water with wells or drains for reuse or discharge into surface water. Techniques for predicting the underground flow system are presented.

Notes: Bore hole sampling of loose saturated sands and gravels forms a very important part of water well investigations. The materials are often difficult to sample and the adoption of adequate equipment and techniques can sorely tax the ingenuity of the driller.In some situations, the standard exploration sampling procedures can provide satisfactory information, while in others, it is necessary to resort to more precise techniques.A great variety of samplers have been designed including types such as open drive, piston drive, jet and extension flap samplers. No single sampler can cover the very wide range of material conditions and operational requirements which may be met during the drilling of water wells.In extreme circumstances, particularly for uncemented or poorly cemented gravels, it may be found necessary to stabilize the strata prior to sampling.

Notes: When the Lake George sewage treatment plant was put into operation in 1939, it was described as a “complete treatment” plant. This was because the treated effluent is discharged onto natural delta sand seepage beds which are “at least 25 feet deep.”Studies were made to determine the removal efficiency in the sand beds of coliforms, BOD, chlorides, and the nitrogen and phosphorus compounds.It was found that when beds were dosed, they were no longer saturated with water at 15 feet. Ten feet of sand were found to remove coliforms by 99% and BOD by 96%. However, nitrates, phosphates, and chlorides remained in significant concentrations after filtration through 10 feet of sand. Phosphate removal in an infrequently used sand bed was greater than in a continuously used bed.

Notes: At the Savannah River Plant near Aiken, South Carolina, as at other locations where there are chemical separations plants for the processing of nuclear fuels, the high-level radioactive wastes are stored in concrete and steel tanks buried just beneath the surface of the ground. This waste is of such activity and longevity that it cannot be dispersed into the environment, but it must be contained for periods of time extending at least into hundreds and perhaps thousands of years. One concept for the terminal containment of this waste is to store it in excavated chambers within the bedrock, which is covered by about 1000 feet of Coastal Plain sediments at the plantsite. As part of the safety evaluation of this concept, the geology and hydrology of both the Coastal Plain sediments and the bedrock have been studied. However, intensive investigation of bedrock waste storage has now been deferred pending more detailed evaluation of alternative concepts of waste storage and management.In the studies completed, a buried Triassic basin that might have potential for waste storage was discovered beneath the southern third of the plantsite. Investigation into the characteristics of this basin was started in 1971. This was not an engineering or design study but was aimed at understanding the geohydrology of the Triassic basin to determine its compatibility with the safe storage of waste.Seismic surveys, gravity and magnetic surveys, and the drilling of several exploratory wells indicate that the Triassic basin is about 30 miles long, 6 or more miles wide, and perhaps 5300 feet thick. One well penetrated the Triassic border, a second was in the center of the basin, and a third investigated an inferred intrabasin fault. The rock is predominantly mudstone of very low permeability with a few lenses of poorly sorted gritty sand. The water yield of all the exploratory wells is extremely low, and water-transmitting fractures are virtually nonexistent.In two wells within the basin, heads above land surface have been measured that cannot be explained by connection with a recharge area. Ten possible explanations have been evaluated: aquifer head, fossil head, tectonic compression, rapid loading and compaction of sediments, water derived from igneous intrusions, infiltration of gas, precipitation of minerals, phase changes, temperature increase, and osmotic membrane phenomena. Systematic evaluation, particularly of the time for dissipation of an elevated head to the head of its surroundings, eliminates most of these explanations. Those that remain as possible explanations are: tectonic compression, temperature increase, and osmotic membrane phenomena. It is not known at present whether the high head is general over the entire basin or only in segments of it.

Notes: Many tube wells drilled for irrigation use fail prematurely because of poor well design, improper sized and placed gravel-pack material, and ineffective slotted-pipe screens. Well and gravel-pack design criteria and an improved slotted-pipe screen described in this paper offer promise of drastically reducing such failures. Properly designed tube wells equipped with this type of screen should have more than double the safe-yield and service-life capability of most irrigation tube wells now in use.In some countries large-diameter, low-capacity open wells always have been used to obtain irrigation water. Now, small-diameter, high-capacity tube wells are being constructed in the same aquifers. As extensive tube-well development occurs, the water table will drop, drying up many shallow open wells. In such instances, those who can afford the deeper, more expensive tube wells could gain almost exclusive use of the aquifer.Optimum development of surficial aquifers using both tube and open wells may have to be rigidly controlled to assure every farmer a fair share of available water. Such controls should be based on the potential safe yield capability of aquifers. A graphical procedure used in Illinois to obtain an estimate of this value for planning and initial development purposes is presented in this paper.

Notes: A mathematical model was developed and used to simulate the stream-aquifer system in the Arkansas River valley in southeastern Colorado, from Pueblo to the Colorado-Kansas State line. The model simulates the interrelations among ground water and surface water including reservoirs, losses, and transmountain diversions, utilizing various water-distribution rules. The model was used to analyze 24 water-management plans designed to reduce shortages in the irrigation supply. One management plan simulated salvage of water from phreatophyte evapotranspiration, different reservoir operation regulations, use of imported ground and surface water, a new reservoir, additional ground-water use, and application of excess streamflow. The resulting annual dependable supply was increased from 610,000 acre-feet to 870,000 acre-feet in relation to an annual demand of 1,100,000 acre-feet. The model can be used as a tool to analyze other water-management plans.

Notes: Two antigenically distinct populations of b-negative light chains have been identified in the serum of two b locus homozygous rabbits undergoing total b locus suppression. Whilst one population of molecules is readily detected in all rabbit sera and represents the previously described lambda chain, a second and minor population of b-negative molecules is detected which is readily detected in normal rabbit serum only rarely. Thus, it appears that it is not specificities of the c7-, c-21 system that are being detected but rather a previously unrecognized allotypic system or the products of a different light chain locus.

Notes: Two genetically inbred strains of rats with new histocompatibility alleles—the KGH and WKA strains—were characterized. Neither the KGH nor WKA strain cells reacted with known Ag-B * specific antisera; specific antisera against these strains did not react with cells from any known Ag-B group; and there was no cross-reactivity between the histocompatibility antigens of the two strains. On the basis of these data, the KGH strain was assigned the Ag-B7 allele and the WKA strain, the Ag-B8 allele. Both strains were low responders to the test antigen poly(Glu52Lys33Tyr15). In various crosses, the antibody response segregated as expected, i.e. low response was associated with the Ag-B7 or Ag-B8 alleles in the F2 and backcross generations.

Notes: The relationship between the mixed leukocyte reaction (MLR) and the serologically defined antigens of the major histocompatibility complex was examined in twenty-three strains of genetically inbred rats. Interstrain cell combinations involving representative members of the different major Ag-B groups were associated with significant MLR responses. Strain combinations within a single Ag-B group were never associated with significant MLR responses, suggesting that non-Ag-B loci probably do not play an important role in MLR reactivity among inbred strains of rats. The WKA and KGH strains, representing newly defined histocompatibility groups, were also examined. The WKA strain (Ag-B8) showed positive MLR responses against representative members of all the different Ag-B groups, including the KGH strain. The KGH strain (Ag-B7) had positive MLR responses against all Ag-B groups except Ag-B1: no reactions occurred with three strains in this group, and inconsistent and weak reactivity was observed with a fourth strain (F344).

Notes: The amino acid sequence near the N-terminus of a human immunoglobulin (Ig) light (L) chain has been determined. This sequence is more homologous to avian Ig L chains than to human Ig L chains, and defines an additional variable (V-) region subgroup designated as VλVI. These data also suggest that all vertebrates share large numbers of Ig V-region genes and that 'species-specific’residues reflect the expression in different species of different sets of V-region genes. Control at a level equivalent to ‘regulatory genes’* determines which genes are expressed. Our findings raise a question concerning the possible role of redundant DNA, in that at least some of the ‘nonsense’ DNA in one species may actually be 'sense’DNA in another. We hypothesize that in evolution‘gene expansion’is a regular mechanism for the generation of new genes and that different members of a given group of repetitious genes are expressed in different species. Such a phenomenon is basically similar to the‘mechanism’controlling the differential expression of genes during embryonic differentiation. Our hypothesis differs from the previous version of the germ-line hypothesis proposed for genetic control of antibody variability which involves ‘sudden excessive gene expansion and contraction’. Evidence suggesting that the‘gene expansion’mechanism may also be applicable to a lesser degree to other gene systems is briefly reviewed and discussed.

Notes: Stepwise incubation with specific H-2 antibody and rabbit-anti-mouse Ig was used to modulate the expression of selected H-2 specificities on the surface of lymph node cells or EL 4 leukaemia cells. Modulation was reflected in a loss of sensitivity to complement-dependent lysis and a polar pattern of immunofluorescence (‘capping’). Specificity H-2.5 on H-2a cells was co-modulated with H-2.11 and so was H-2.11 with H-2.5 on H-2k cells. However, when H-2.11 on H-2k cells was modulated, the cells did not loose cytotoxic sensitivity for H-2.5. This asymmetry in co-modulation of H-2.5 and H-2.11 may be accommodated by the duplication model of the H-2 complex which postulates a double determination of H-2.5 in the H-2k (unlike H-2a) chromosome, with one determinant being in the K region (where also the H-2.11 determinant is located) and the other in H-2D. The modulation results with H-2.5 and H-2.11 are compatible with the view that various H-2K specificities may represent distinct antigenic sites on the same glycoprotein molecule whereas H-2D specificities are on separate molecule(s). The independent modulation of H-2D.4 and H-2K.11 specificities further indicates that molecules of the two classes are also secondarily not linked in the membrane structure. Modulation-induced cytotoxicity resistance was further shown to persist even when the specific H-2 antibody is newly added; this suggests that it is a change in the distribution of the H-2 antigen to be held responsible (rather than the loss of the sensitizing antibody).A modulated expression of a certain H-2 specificity might then be expected to affect its blocking relationship to another H-2 specificity; the blocking index expresses the degree of interference by antibody attached to one of them with the attachment of antibody to the other. The blocking relationship between H-2.4 and H-2.11 was shown to be completely abolished by the independent modulation of H-2.11. In contrast to this, the blocking index for H-2.5 and H-2.11 remained practically constant following the modulation of either specificity; this indicates that the intramolecular configuration of such two H-2 sites may not be altered by the gross redistribution of the whole molecule in the plane of the membrane. The rigidity of this configuration seems to be maintained by neuraminidase-sensitive groups as suggested by the reduced blocking index in neuraminidase pretreated cell.

Notes: The effects of varying degrees of multiparity on placental and foetal weights were examined in BALB/c female mice pregnant by either BALB/c or C3H males. Continual decreases in placental weights are observed through third pregnancies followed by progressive increases in both syngeneic and allogeneic placentas. In syngeneic pregnancies, foetal weights are generally proportional to placental weights, but those of allogeneic pregnancies tend to oppose placental weights. Evidence is presented that placental weights are also influenced by foetus-specific antigens and the genotype of previous litters. In this strain combination, placental weights reflect changes in maternal reactivity different from those previously reported with tumour allografts.

Notes: The Ag system, inherited antigenic determinants on serum low density lipoprotein and Australia antigen (Au), an antigen associated with an infectious agent which can cause hepatitis in man were discovered by reacting in immunodiffusion tests sera from multiply transfused patients and sera from geographically human populations. The approach has been pursued in the experiments described herein and has resulted in the identification of seventeen precipitating systems. They are different from the previously described anti-Au and anti-Ag precipitins. In some cases they may be confused with Australia antigen precipitins, and care should be taken in the evaluation of Au test systems where comparisons with antigen controls are not routinely performed.

Notes: Book Review in this Article. Einfiihrung in die Immungenetik, Grundlagen der Modernen Genetik 9, KLAUSDIETER BAUER

Notes: A new type of Gm genetic marker combination in an IgG1 immunoglobulin, Gm(z) together with a non-a marker, is here described. This indicates the presence of a new gene, Gmz,non-a, which most likely originated on the basis of an intragenic recombination at the IgG1 cistron. Immunochemical and immunogenetic studies showed that no other IgG1 Gm markers were expressed by the unusual gene, and there was no evidence for deletions or duplications at the IgG1 cistron.

Notes: The cell mediated lympholysis (CML) test is normally carried out in 2 steps–first, the lymphoid cells are allowed to interact in mixed allo-culture (MLC) and secondly, they are reacted against chromium labelled phytohaemagglutinin transformed lymphoblast cells, carrying the appropriate target allo-determinants. The genetic control of target structures has already been localized to the H-2D and H-2K regions of the H-2 gene complex, but the genetic basis of the generation of effector capacity is not understood and is the subject of this report; the suggestion that there is a separate genetic basis came from the observation that H-2D and/or H-2K region incompatibility alone was insufficient for CML to occur and that incompatibility at the Ir-Ss-Slp regions of the H-2 complex was also required. In the Ir region also reside the genetic control for the strong lymphocyte activating determinants (LAD) of the H-2 gene complex and it was thought possible that they might also be responsible for activating the effector cells for CML.The genetic experiments were done with congenic resistant and recombinant mouse strains, so it was possible to study in relative isolation, and in selected combinations which of the various defined regions of the H-2 gene complex control the initiation of effector capacity in CML.Five day,‘one-way’(parent-F1) mixed lymphocyte cultures–incompatible only for defined regions of the H-2 gene complex were reacted with 51Cr-labelled PHA blast cells and the specific chromium release was calculated.The results give evidence for a separate but closely linked genetic control for the effector cell stimulating (ECS) and LAD functions. The ECS genes map between the LAD and Ss-Slp genes of the H-2 complex.

Notes: Gonad development was studied in young carp of the European and Chinese (big-belly) races. The effects of age and body weight on gonad and egg size were partitioned and the following findings were made: (i) Gonad weight was correlated, in both males and females, with body weight, but proportional gonad weight, i.e. the ratio gonad weight divided by body weight, was independent of body weight, (ii) Proportional gonad weight had reached its maximum value in one year old males, but it more than doubled in two year old females, (iii) Egg size of two year old females was more than twice the size of eggs of one year old females, (iv) The European and Chinese races of carp differed in several aspects of gonad development. In particular, the Chinese matured earlier and their relative gonad sizes were considerably larger, (v) Genetic variation in gonad development was also found within the European race, where faster rate of development is dominant over slower rate. The evolutionary implications of the above differences were discussed.

Notes: Changes in haematocrit values under lowered oxygen tension and aerobically treated blood samples of rainbow trout Salmo gairdneri (Richardson), landlocked Baltic salmon S. salar (L.), brown trout S. trutta lacustris (L.) and lake trout Salvelinus namaycush (Walbaum) have been studied in vitro. The mean haematocrit value increased during 2 h incubation under lowered oxygen tension by 32.7 ± 3.1% in rainbow trout, 28.2 ± 2.8% in landlocked Baltic salmon, 29.2 ± 5.6% in brown trout and 25.2 ± 2.8% in lake trout. During corresponding incubation with oxygen the mean haematocrit value decreased below the starting level by 18.1 ± 1.9% in rainbow trout, 18.3 ± 4.8% in landlocked Baltic salmon, 22.4 ± 0.7% in brown trout and 11.8 ± 1.7% in lake trout. Consequently, the changes in the haematocrit values were greater in the species belonging to the genus Salmo than in that of the genus Salvelinus. The increase in the haematocrit values seems to have resulted from swelling of the erythrocytes and their decrease is similarly attributable to shrinking of the cells. The reasons for this swelling, which may be complicated, and its apparent significance for haematocrit determinations are discussed.

Notes: Wild plaice and flounders with lymphocystis were sampled and their lesion distribution noted. Regression of the lymphocystis cells was seen by histology and a host response including macrophages and immune cells occurred. Antibodies were detectable by a double diffusion precipitin test. The epidemiology is discussed with reference to these findings and to the life histories of the two species.

Notes: The stomachs of 148 elasmobranch and teleost fishes representing 35 families and 62 species were examined by viscometry for cellulase activity. Sixteen species of Georgia estuarine fish and the freshwater fish, Ictalurus punctatus (Rafinesque) showed some cellulase activity. Elasmobranchs and teleosts captured in Florida Bay, Florida, and over the continental shelf off Georgia lacked cellulase activity. Cellulase activity in fishes is probably produced by microflora of the alimentary tract.