ALBERT

Notes: When the fixed-source electromagnetic method is applied the quantities measured are influenced by the resistivity of the whole environment. This occurs mostly in the cases of measurements in areas with prevailing high resistivities, and if a weathered layer with considerably lower resistivity than that of the original rock has been formed near the surface. For this reason it is important to be acquainted with the properties of the two-layer ground with an overlying conductive layer.In the present paper attention will be drawn to theoretical calculations connected with the field of the homogeneous ground and that of the two-layer ground.

Notes: Results of rock magnetic investigations and magnetic field measurements in the Logar Valley, Afghanistan, are presented. Rock magnetic investigations on samples of the ore and the country rock have demonstrated that the chromite is strongly magnetic, whereas the country rock has proved predominantly non-magnetic, partly weakly magnetic. The isanomalic maps show strong anomalies of some 1000 γ above the known chromite occurrences. Anomalies of the country rock amounting to some 100 γ have been observed only above basic dikes. The measured anomalies have been interpreted quantitatively by 2- and 3-dimensional models. This interpretation is demonstrated and the question of chromite detection discussed. Model graphs are used to investigate in detail whether the extension in depth of ore bodies can be estimated.

Notes: This work deals with a theoretical investigation of the magnetotelluric sounding where the horizontal layers of a geological section do not have a sharp but a transitional boundary. The ratio of the horizontal electric to the horizontal magnetic components gives a measure of “Cagniard impedance”, which together with the phase relationship between them, enables one to determine the subsurface geometry and the true resistivities.Utilising the principle of similitude a set of Resistivity Master Curves and the corresponding phase relationships are presented here for the case where the lower half-space is infinitely resistive. The relation between the relative transition thickness and the cut-off period is illustrated.

Notes: A point source or a dipole source of electric current, placed on a randomly layered semi-infinite medium, produces an inhomogeneous random potential field on the surface. The variance of the random potential, normalized with reference to the normal field (that is, a field due to a point source or a dipole source on a homogeneous medium), falls off inversely as the distance from the source. The conductivity of the layers is assumed to vary randomly about a mean value (unity) such that the variations can be represented by a zero mean homogeneous random function. Further the variations are assumed to be small compared to the mean so that the first order perturbation is adequate. The analysis shows that the dipole field is more sensitive than the single pole field to the conductivity variations.

Notes: Book reviewed in this article:F. Link, Eclipse Phenomena in AstronomyMarine Geophysical Researches–an International Journal for the Study of the Earth Beneath the SeaM. K. Polshkov (editor): Exploration Geophysics, Vol. 48

Notes: The relationship between porosity and formation factor in unconsolidated homogeneous and anisotropic sediments without granule-liquid interaction is investigated by introducing a parametric model that simulates a variable cellular structure.In this hypothesis, porosity φ and F-factor are calculated for some fixed values of the parameter, solving numerically two integral expressions.From these calculations the form of the function φ=f(F), corresponding to the proposed model, has been deduced. This relation is in very good agreement with Archie's empirical law for unconsolidated sands which requires that F=φ--1,3. Therefore it seems that the validity of Archie's law is theoretically confirmed for the unconsolidated sediments considered in this paper.

Notes: In a previous publication (Koefoed 1968) a function called the “raised kernel function” has been introduced as an intermediate function in the interpretation of resistivity sounding data, and methods have been described both for the determination of the raised kernel function from the apparent resistivity function, and for the determination of the layer distribution from the raised kernel function.In the present paper a procedure is described by which the second step in this interpretation method–i.e. the determination of the layer distribution from the raised kernel function–is considerably accelerated. This gain in interpretation speed is attained by the use of a standard graph for a function which defines the reduction of the raised kernel function to a lower boundary plane.

Notes: Despite the use of CDP and digital methods the Zechstein base is still the deepest horizon in the vast salt-dome basin of Central Europe for which continuous information can be obtained by reflection seismics. Thus in North-western Germany, in addition to reflection seismics, the refraction seismic method has been increasingly used for a reliable survey of deeper horizons.The first part of the paper deals with the investigation of the various possibilities and limitations of refraction seismics with regard to the investigation of Pre-Zechstein layers in a basin with a tectonically very complicated overburden. The recording techniques specially developed for continuous profiling of the desired refraction seismic arrivals and the data processing methods are described.The main problems of interpretation are then discussed, in particular with regard to depth representation. The advantages and disadvantages of the various methods, e.g. Gardner's, Hales' and Wyrobek's, and of the wave-front method, are compared. On account of the tectonically complicated overburden Thornburgh's wave-front method proved to be the most useful.In a further section the various possibilities for velocity determinations are mentioned, e.g. Wyrobek's determination of the overburden velocity, for which the wave-front method automatically furnishes the necessary corrections to a deep datum.Finally, some examples are given for the results obtained, including some incidental information on the deeper crust.

Notes: Two alternative types of diagrams are shown which allow the direct conversion of readings taken by certain types of proton magnetometers into magnetic field strength. The accuracy of these diagrams is discussed and found to satisfy the requirements.

Notes: In order to locate relatively optimum sites for drilling exploratory holes for fresh water, an electrical resistivity survey was conducted along the new Mahukona-Kawaihae Road on the west flank of the Kohala Mountain. Two resistivity soundings made at the same stations, using the Schlumberger electrode configuration, determined an a spacing of 275 feet for horizontal profiling with the Wenner array.The correlation coefficient of the elevation to profile data was 0.41. A procedure for removing elevation effect from observed apparent resistivity was developed. Based on the reduced resistivity profile, four relatively optimum sites for additional exploration, such as by drilling, are specified. There is no specific interpretation of the data that can definitely indicate the occurrence of large underground reservoirs of fresh water anywhere along the profile. This is because the interpretation of horizontal profiling data is essentially relative and not absolute.

Notes: The seismic velocity of sedimentary rocks is determined by the porosity, the velocity in the matrix and that in the fluid. The last two are known experimentally. The velocity can be measured from the surface. By applying the time average equation we can find the porosity. If the only difference at two points is the nature of the fluid in one layer, the ratio of the reflectivities of the layer at these points determines the nature of the fluid; this ratio is equal to the ratio of the amplitudes at these points. The size of the reservoir can then be found.The method can be applied to both oil exploration and production. It is more accurate in the latter case because more information is available than in the former case. The method is also more effective in developing discovered fields than the conventional method of relying only on the geological structural configurations.

Notes: It is pointed out that after identifying reflection events from the same horizon on two records obtained on the same spread from two different shotpoints, one can simultaneously estimate parameters of reflection events and relative static corrections. The parameters of reflection events are treated as quantities to compute whereas relative static corrections are treated as quantities to minimize by the least squares method. Static corrections obtained from different horizons for the same point on the spread are averaged.The case of more than one pair of records for the same spread (or part of the spread), vital for multiple coverage, is also discussed.

Notes: Après avoir essayé?analyser, par voie optique, ľeffet de la réflexion fantôme sur des enregistrements sismiques, on montre ľapplication de deux méthodes de filtrage de ce fantôme sur des exemples réels.La première méthode utilise là mise à feu séquentielle de charges situées à différentes profondeurs dans un même trou; il s'agit ?un filtrage réalisé sur le terrain. Le deuxième procédé consiste à filtrer, au central, des enregistrements réalisés à des profondeurs de tir différentes avant de les sommer.

Notes: A high sensitivity thermometer using a thermistor sensing element was designed for practical measurements in the field.The most suitable procedures for the elimination of diurnal and seasonal variation of temperature, the influence of vegetation cover and of other effects were investigated.Positive results of geothermic measurements have been acquired on sulfide deposits. By far the most important results of geothermic measurements have been obtained in hydrogeological problems, e.g. the investigation of circulation of underground water. In the case of prospection for cold mineral waters the combination of geothermic measurements with gasometric analyses is very useful. As the classical domain for geothermic investigation, prospection for hot water is to be mentioned.

Notes: The conditions for creating and recording converted waves in the area of the Panonien basin are considered. Comparison between the characteristics of converted waves recorded in the field and characteristics of converted waves calculated for the model which approximately corresponds to lithophysical conditions of the area is made.The comparative interpretation of the crustal structure along the profile, using different types of waves, is given.

Notes: Direct interpretation methods of resistivity curves are discussed, which use the kernel function of the apparent resistivity. This function results from the consideration of the problem of diverse electrodes configurations.Several expressions for the determination of the kernel function of the potential from the kernel function of the apparent resistivity are given.

Notes: A method to analyse aeromagnetic profiles is proposed: several horizontal (width-) and vertical (amplitude-) parameters are deduced from the anomalies. These parameters are then compared with diagrams drawn on a logarithmic scale. The comparison yields depth and magnetization of the causative bodies.The method lends itself equally well to a quick estimate and to a thorough interpretation, depending on the number of parameters deduced and on the number of diagrams. It can be applied also to the anomalies of the total field and its vertical gradient.

Notes: Book review in this Article:H. Wöhlbier, R. H. Wöhlbier, F. H. Wöhlbier, H. Baston, Worldwide Directory of Mineral Industries Education and Research.

Notes: Water seepage from reservoirs causes appreciable anomalies of natural electric fields. The possibility of mapping leakage places by means of the SP method has been discussed by the authors in an earlier report. Further work has shown that detailed measurements of the natural electric field allow to determine the seepage rates from individual areas of a water reservoir in relative units. If data on the total discharge from a water reservoir are available, the conventional seepage units can be converted into absolute ones. Using this technique on a water reservoir in Armenia has permitted to control the change of the leakage rate as hydroinsulation operations were in progress. It has been established that as a result of shielding the bottom with clay material leakage from the central part of the reservoir has stopped. On the other hand, construction of cement seepage-proof protection has had so far no appreciable positive effect.

Notes: The seismometer-ground system is represented by a damped oscillatory system. Relatively simple approximation formulas are derived to express the coupling between ground and seismometer. These expressions are applicable in seismic exploration. The coupling is that of a mass, suspended by a spring, to the surface that the ground would have in absence of the seismometer. It results in a low-pass filtering of the ground motion, which is due to the presence of the seismometer. This effect is expressed in a unit-impulse response. It appears that, over a sufficiently homogeneous ground and for low frequencies, one has a true coupling between ground and seismometer. To obtain a sufficiently large pass-band, a low seismometer housing-mass together with a not too small housing radius are necessary.

Notes: One of the most important aspects in interpretation of gravity and magnetic anomalies, which generally represent the sum of many effects from the subsoil, is that these effects cannot be adequately separated into individual effective anomalies by means of known procedures. Moreover, the concept itself of anomaly separation must be expanded in a certain sense, because the addition of these effects in the mapped anomalies can arise from many structures situated in the subsoil in different relative positions to one another. A combined procedure is proposed, based on Fourier analysis utilising both periodic complex functions and nonperiodic ones, by use of which the number of individual effective anomalies cumulated in the mapped anomalies is obtained. In order to illustrate the use of this procedure and the advantages of obtaining more valuable informations on geological causes of anomalies, one example from Romania is given.

Notes: A number of electrical resistivity arrays are available to the exploration geophysicist in the conduct of vertical or horizontal profiling. The advantage of using central-type arrays which produce large potential drops, such as the Wenner or the Schlumberger, must be weighed against the ease of acentral arrays such as the polar and equatorial arrays.A series of nomograms has been designed to provide a means of rapid calculation of the potential drop to be obtained by any of the various central and acentral arrays, as a function of apparent resistivity, electrode spacings and available transmitter power. The same nomograms may also be used for approximate computation of the apparent resistivities in routine surveys. However, the accuracy of resistivity calculation is directly related to the accuracy of drawing lines between the scales and hence is rather limited in reduced-size nomograms in this paper.

Notes: In the theoretical part of the present paper, formulas have been analyzed for a magnetic dipole in a homogeneous and unbounded medium. The magnetic field is elliptically polarized in the region between the quasistatic zone and the far field. Since the position and the shape of the polarization ellipses depend on the complex wave number, k, it is possible to determine k by measuring the polarization ellipses. From k, the conductivity and the dielectric constant of the medium are easily calculated. The functions required for the measuring method have been computed and plotted in graphs.In the experimental part it was examined how far the theory may be applied to measurements of propagation through rock at frequencies ranging from 100-1000 kHz. These measurements showed that reasonably defined mean values of rock parameters can be given only if the deviations of the field from the theoretically expected field are not too high. These deviations have been named field distortions and have been examined by means of statistical methods (variance ratio tests). Gallery cavity and inhomogeneity or anisotropy of the medium account for these distortions.

Notes: Non dynamite seismic energy sources have shown only limited success in difficult shallow-water or marsh prospect areas, and none have applicability to both environments. Recently, a method has been devised to adapt a marine pneumatic source for operation in abrasive surroundings. A system composed of four of these modified sources together with associated emplacement and retrieval mechanisms has been developed and has proven to be a reliable and efficient seismic energy source for both shallow-water and marsh applications.

Notes: On présente des profils de sismique réflexion obtenus dans la partie Sud-Est du Golfe de Gascogne en eau profonde avec raccordement au plateau continental.La technique employée était celle du Flexotir à un ou deux canons en couverture triple. La charge totale par tir était égale à 50 ou 100 grammes suivant les cas. La vitesse du navire était ?environ 6,5 nœuds, ce qui a permis de couvrir 1000 kilomètres de profil en 9 jours de travail. La distance entre traces sur les coupes est de 60 mètres, ce qui per-met une étude assez détaillée.De bons résultats ont été obtenus par des fonds allant jusqu à 4000 mètres. La pénétration sous le fond atteint souvent 5 secondes (temps double).Le Flexotir constitue une méthode de prospection sismique bien adaptèe àľocéano-graphie de grande reconnaissance.

Notes: A second deep Schlumberger sounding has been carried out in South Africa, this time using a newly completed power transmission line, not yet in sevice, as emission line. The maximum current electrode separation attained was 600 km. The sounding was situated on a shield area with a thin cover of sedimentary rocks (Karroo System) overlying the archaean granite. The center was chosen near to the village of Dealesville.It is shown that lateral effects at large AB spacings are unlikely, but due to numerous dolerite intrusions in the sediments surface electrode effects must be guarded against; thus AB positions were chosen by geologists. Because of a low signal/noise ratio at large AB spacings the measurements were treated statistically; in particular, the elimination of non-random events improved the measuring accuracy.Although a thin conducting layer at the base of the sedimentary succession decreased the resolution of the sounding curve, the results, which were interpreted with the aid of a computer, show positively that〈list xml:id="l1" style="custom"〉(a). the crust is multi-layered with a highly resistant portion having a minimum resistivity of 15000 ohm.m and(b). a good, thick conductor appears as the final layer.The Dealesville results are in complete agreement with those obtained from the first deep Schlumberger sounding at Pofadder (Van Zijl 1969) except that the transverse resistance of the lowermost resistant crust is about 100% larger at Pofadder due probably to a second period of metamorphism. Both electrical studies support the view of a dehydrated lower crust (granulite facies).

Notes: A two-coil induction logging system in an infinite homogeneous medium has been theoretically analysed for the relative contributions of various ground elements to the total signal at the receiver. Unlike an earlier approximate treatment by Doll (1949), the present analysis takes skin effect into account (while neglecting displacement currents). Contour diagrams depicting relative contributions from every ground point and diagrams for vertical and radial/lateral investigation characteristics are presented. The results differ significantly from Doll's in the following points:〈list xml:id="l1" style="custom"〉1The relative contribution is frequency and conductivity dependent;2It does not show symmetry with respect to the center of coil system;3It alternates between positive and negative values with distance;4Real and imaginary contributions for a given conductivity and frequency are different from each other.The possibilities of a horizontal-horizontal sonde is briefly examined and found to be inferior to the usual sonde because of its higher sensitivity to the mud column and the invaded zone.

Notes: The paper deals with the early stages of development of a convenient form of electromagnetic induction method of sounding referred to as ‘Central Frequency Sounding’ and abbreviated as CFS. The method is introduced as a rapid and useful technique for investigation of shallow engineering and hydro-geological problems. Sets of theoretical two-layer master curves, suitable for interpretation of field data involving measurement of the vertical magnetic component of the field induced at the center of a loop placed on a two-layer earth, have been presented.The approximate but reasonably accurate solutions for a two-layer earth of any arbitrary resistivity contrast have been considered for the purpose and expressed in a form suitable for computation. The computed results have been presented in sets of curves useful for interpretation of field data.

Notes: Book reviewed in this article:J. A. Jacobs, Geomagnetic Micropulsations.G. Kunetz, Principles of direct current resistivity prospecting.T. Rikitake, Electromagnetism and the Earth's Interior.E. Orellana and H. M. Mooney, Master Tables and Curves for Vertical Electrical Sounding.

Notes: La polarisation provoquée (P.P.) est un phénomène particulièrement complexe non seulement du point de vue des mécanismes physiques qu'elle met en jeu, mais aussi du point de vue mathématique. A cause de ľanalogie que présentent les techniques expérimentales de sondage électrique classique de résistivité?une: part, et de sondage P.P. ?autre part, on éprouve une certaine tendance à interpréter les données du second à la manière du premier. C'est pourquoi il nous a semblé utile de calculer un modèle mathématique idéalisé et schématisé qui permette tout au moins de se rendre compte de ľallure générale du phénomène auquel on peut s'attendre. On s'est placé dans le cas le plus simple, celui ?une couche mince polarisable qui présenterait la même conductibilitéélectrique que le milieu dans lequel elle est intercalée. On se propose de fournir le résultat de ce calcul pour le cas simple ?une seule électrode ?injection et ?une seule électrode de mesure et, à partir de ces données, de calculer ľallure ?un sondage P.P. de type classique avec quadripôle Wenner.On compare ensuite le diagramme calculé avec une courbe expérimentale obtenue sur un modèle figurant une couche mince de minerai disséminé II s'avère, en fin de compte, que ľallure générale du phénoméne fournit une base de contrôle solide àľexpérimentation sur modèles réduits.

Notes: In seismic studies being carried out to elucidate the structure at depth of the Midland Valley rift and the Tertiary igneous province in the West of Scotland, a lack of deep boreholes makes the collection of velocity data imperative for identification of seismic events and for determinations of depth. Three methods are used to investigate the correlation of seismic velocities and geological formations. The results show as strong a dependence of velocity on method of measurement as on lithology and the wide spread of values within a given formation makes the attribution of discrete velocity ranges to specific formations impossible. Changes of velocity are more significant than absolute values. The variations in both are discussed.

Notes: Measurement of the depth to water in wells can be accomplished by timing the fall of a marble or BB. Depth to water can also be determined in terms of the frequency of the reverberations heard in a well. These two methods are called the rock and the bong techniques respectively. Their theoretical basis, their proper execution, and their usefulness are discussed.

Notes: The feasibility of determining the ground-water contribution to stream flow during periods of storm runoff by continuous monitoring of a stream's electrical conductance was investigated. Methods involving graphical techniques or ground-water stage versus base flow rating curves are generally used to determine the ground-water contribution, but the ground-water contribution can also be estimated if stream flow and the conductance of surface water and of ground water are known. The conductance method was tested on a 95-square-mile basin in north-central Illinois. Continuous records of stream flow, stream-flow conductance, and ground-water stage within the basin were collected. A rating curve of base flow versus mean ground-water stage was constructed, and ground-water discharges determined from the rating curve were compared with those computed from conductance data. The conductance method normally gave a lower estimate of the ground-water contribution than did the rating-curve method. However, analyses of storms which were preceded by extended dry periods resulted in much lower estimates of ground-water discharge by the rating-curve method than by the conductance method. The conductance method offers a simple alternative for use in areas where observation wells are unavailable or where rating curves are difficult to construct.

Notes: Observation wells and access holes for neutron probe use were drilled by a jet-percussion drill rig in coarse alluvial material near Tucson, Arizona. The method combines the jetting action which effectively removes loose materials with the percussion necessary to break up tighter formations and large particles. A unique feature of the equipment is the provision for simultaneous drilling and driving the casing to keep the hole open in loose formations. Washed samples of the material being drilled can be obtained from the recirculating water system. Drilling rates were from seven to ten feet per hour, and costs including casing were less than $1.50 per foot. Maximum depth is about 100 feet.Hydrologic study of a ground-water reservoir requires access to the aquifer. Observations are made where the water table intersects the land surface, such as at springs or seeps, or through existing wells. However, wells are not always found in desired locations or are pumped so heavily that their usefulness as observation wells is impaired. Measurements are also made in the unsaturated zone with neutron moisture measuring equipment, which requires a small diameter cased access hole for the neutron probe.An observation well needs a diameter only large enough for access by measuring devices and must be immediately responsive to changes in aquifer water level. For neutron probe use, the required diameter is about two inches, and the well must have no significant effect on moisture movement in the unsaturated zone. To meet these requirements the drilling process should have no lasting effect on the formation surrounding the well. Finally, since the wells have no economic utility, construction cost must be low.A network of observation wells and neutron probe access holes was drilled as part of a project to evaluate the natural recharge from Rillito Creek near Tucson, Arizona. The formation along the creek bed is a coarse alluvial outwash containing almost no clay, considerable running sand, and some large gravel and boulders. Commercial churn (percussion) and hydraulic rotary drills, commonly used for drilling in this area, were first tried but encountered much difficulty in the loose materials.Previous investigators used jetting equipment drill small diameter holes in a variety of alluvi formations (Cederstrom and Tibbitts, 1961; Bowma: 1911; and Pillsbury and Christiansen, 1947). Howeve in most cases, either open hole drilling was used because the fine material content and the limited numb. of boulders or large gravel particles made this methc possible, or drilling mud was used to maintain th hole. The jetting method uses water pumped unde pressure through hollow rods and a drill bit to loose the material and carry it to the surface. The jettin water receives little aid from the drill in loosenin the material to be removed. Usually the drill cutting are settled out in a tank or basin, and the water i recirculated.

Notes: Under steady state conditions of flow, the seepage toward a single gravity well is governed by the Laplace Equation which may be written in terms of either the hydraulic head, the pressure head or the velocity potential. Although this equation is linear, the principle of superposition cannot be applied to sum up the individual effects in the case of a multiple gravity well system due to the variation of the flow domain under the effect of one or several wells. A method is presented allowing the use of the superposition principle in a restricted form. The superposition of the decrements of the base pressure heads than the initial heads before pumping is valid. Also the decrements in the areas of the pressure head diagrams across specific vertical sections than the original areas can be summed up together.The limitations of Dupuit's well formula are explained. The validity of that formula has been proven on the basis of the analysis of the hydraulic forces within the flow medium, an approach which is different than that given by Hantush and Charney. Furthermore, the derived equation is written in terms of the areas of the pressure head diagrams across vertical sections and termed as the Unified Well Formula because it has been proven that the same formula is also valid for artesian wells.The analysis of the hydraulic forces leads to the development of an equation for the free surface. This equation is then solved numerically in one iterative cycle. Due to the lack of simple available solutions, only one case, previously solved by the relaxation techniques, is compared with the presented method. The maximum percent difference in the depth of saturation within 82% of the flow region does not exceed 3.2% whereas in the remainder 18% of the flow region around the well, the percent difference varies between 2.63% to 4.67%. Even these differences do not really indicate actual errors due to the approximation implied in the relaxation method itself using a coarser grid.This distribution of the hydraulic head across a vertical section is assumed parabolic. Although Polubarinova-Kochina presented a mathematical proof which leads to the same conclusion, yet for the reasons explained in the text, the writer preferred to use this type of distribution as a valid physical assumption.The results of the analysis of each single well are applied to determine the pattern of the interference between several gravity wells. By means of the presented approach, the resultant values of the depths of saturation can be obtained on the basis of the explained restricted procedure, of superposition. The hydraulic potential distribution within the flow medium of a multiple gravity well system can also be obtained. The assumption of the parabolic hydraulic head distribution is maintained in analyzing a group of wells. It is recommended to establish a proper computer program covering a grid system that encompasses all the wells and their individual influence regions in a certain well field.In the entire analysis, Dupuit's assumptions are eliminated. However, the two main assumptions in the given analysis are: (a) the parabolic distribution of the hydraulic head across a vertical section within the flow medium, and (b) the elimination of the circumferential velocities. These two introduced assumptions are -i in the writer's opinion – practically valid.

Notes: Carbonate aquifers with highly developed anisotropic permeabilities and other fractured rocks under water-table or semiwater-table conditions present complex hydrologic settings in which to predict the sustained yield of individual wells or groups of wells. Yields of wells in these settings are particularly responsive to the position of the water level and its relationship to one or more producing zones. Often a well's total capacity may be accounted for by one or more openings encountered in drilling which are separated by varying thicknesses of essentially nonproductive rock. A well s yield is determined more by the position of the water table with respect to these openings than to the proportion of saturated rock penetrated by the well bore.A permeability profile must be defined for. these wells along with their available drawdown, and the inclination of water-yielding openings. Permeability profiles may be roughly estimated from detailed driller's logs and caliper logs, and more precisely determined from flow meter surveys; packer tests and by pumping wells after successive increments of drilling or by a combination of increasing casing lengths and extended drilling. Available drawdown is dependent upon the inclination and position of significant water-yielding openings exposed within the bore hole and seasonal variations in the water-table position. In gently dipping carbonate rocks openings may follow bedding planes or selected beds favoring conduit development. Where this is known to be the case, pumping levels may be allowed to approach the top o.f one or another of these zones depending upon which is most productive.Where openings‘are inclined, pumping levels should be kept well above the depth at which the opening was penetrated to minimize the risk of dewatering conduits where they occur higher in elevation adjacent to the well bore compared to where they were penetrated by the well bore, Test holes may be drilled immediately adjacent to the potential production well to define the inclination of individual conduits or wells test pumped when possible at rates sufficient to draw the pumping level to the top of the opening in question. The latter is preferable because reductions in yield can be observed directly as a function of drawdown. To determine available drawdowns in fractured rocks, a permeability or yield profile, the inclination of openings adjacent to the well and seasonal variations in water levels must be known.

Notes: A field experiment has been installed near Firebaugh in the San Joaquin Valley of California to test submergence of drains as a means of denitrification of ground water. Laboratory and field experiments have shown that denitrification occurs in saturated soil where there is ample organic carbon available for bacterial metabolism. Denitrification and dilution of high nitrate ground water were accomplished in the field.

Notes: As round-water research is accelerated and basic data on aquifer parameters become more abundant, a statistical approach to evaluation of the ground-water regimen becomes increasingly useful. One such statistical technique is the fitting of polynomial trend-surfaces to ground-water levels. Barcholomew County, Indiana was chosen as a test site to derive techniques which could give additional guidance in the selection of areas suitable for the development of future ground-water resources.Trend-surface maps and maps of the deviations from the trend-surfaces were prepared from water-level data and evaluated to establish their relationships with the hydrogeologic regimen. A field-testing program was carried out to evaluate aquifer parameters.On the basis of the results obtained from these studies, the following conclusions were drawn:〈list xml:id="l1" style="custom"〉1A mathematically fitted surface may be considered to approximate the water-table or piezomecric surface, and will be sensitive to fluctuations in the ground-water reservoir.2The anomalous areas of the trend-surface represent local effects superimposed on the regional base and may be explained by a particular set of geologic, hydrologie or man-made conditions.From these conclusions, it appears that trend-surface analysis provides a rapid, inexpensive method of delineating attractive areas for detailed ground-water investigations.

Notes: Accurate measurement of static water levels in wells tapping deeply buried aquifers and aquitards at the Nevada Test Site requires evaluation of and correction for several factors exclusive of instrumentation. Both the drilling method used and the depth of the hole at the time of measurement significantly affect determination of the static water level for the aquitards, and frequently these factors preclude head determination in an economically justifiable time. Density of fluid in the drill stem and hole deviation affect the determination of accurate static water levels for the aquifers. In the principal aquifers, in which hydraulic gradients are as low as 0.5 foot per mile, direct measurement of depth to water is preferable to pressure-gage measurements at the aquifer face. Case histories and graphs are presented to illustrate the magnitude of errors that can result when these factors are disregarded.

Notes: The purpose of well screens and gravel packs is to maintain open access within the aquifer ensuring that thorough development of the well is not impeded by sand. Where a well draws on unconsolidated sands and gravels, or other friable materials, the installation of a screen and pack is essential.The use of correctly designed equipment is important and this paper represents a review of the diverse types available, but does not set out to make any recommendations.Well screen designs should incorporate the following features:〈list xml:id="l1" style="custom"〉1Minimum entrance velocity.2Maximum open area of screen.3Correct design of slots to minimize blockages.4Slot size should match aquifer or gravel pack medium.5Screen material should be corrosion resistant.6Screen should allow for periodic maintenance.Commercial well screens fall into various categories according to their slot designs. A slot shape, offering the maximum open area consistent with strength, is a priority and the material used in screen manufacture has an important bearing on this. Blockage of screens may be caused by chemical deposition formed by precipitation or corrosion products, and coated screens have been introduced seeking to inhibit this.Gravel packs should include the following design features:〈list xml:id="l2" style="custom"〉1Sand free operation after development.2Give lowest possible resistance to permeation.3Offer low entrance velocities.4Be resistant to chemical attack and have an efficient service life.The gravel pack should ensure that the completed well operates free of sand; thus the particle size of the pack depends upon the particle size of the aquifer. Gravel pack design should be guided by standard sieve analysis.It is evident from the variety of claims made for well screens and gravel packs that further research is necessary. It is suggested that the following points need further investigation:〈list xml:id="l3" style="custom"〉•. Improved design of nonblocking opening.•. Design consideration of screen resistance to chemical attack.•. Best type of gravel and optimum thickness of the pack.•. Head loss through the screen and pack.

Notes: Theoretical analyses predicted and experimental observations—confirmed a mechanism by which strong capilary forces hindered instead of helped promote infiltration into soils. Infiltration into an unsaturated soil overlying an impermeable barrier displaces the air from the soil interstices. Unable to escape downward, the air may escape upward in bubbles travelling through large pores, or, if the pores are small and the capillary forces are large, the air is compressed between the wetting front and the barrier. This reduces the infiltration rate and may result in an almost stable wetting front. Under certain calculable conditions the air pressure build-up is sufficient to cause sudden localized horizontal rupturing of the soil at the wetting front and to lift it along with the infiltrating water, forming a cavity. The air-filled cavity breaks the flow passages and percolation ceases through pores terminating in the cavity. Observations with soil columns have shown that when provision was made fot the displaced air to escape less than one minute was required for the wetting front to move three inches; when the air was not free to escape and the soil raptured, two weeks were required for the wetting front to move this distance. Grain size and packing play a role by limiting the capillary pressure build-up and the bubbling pressure. This phenomenon should emphasize precautions to be followed in applying laboratory infiltration results to engineering predictions of field conditions.

Notes: The minimum probability that: anomalous bulges and re-entrants produced by mechanical (as opposed to interpretational) contouring of data on maps actually exist and are not merely the result of measurement errors may be calculated. The calculation consists of computing the compound probability that the value of at least one data point within each anomaly is actually higher or lower than the value of one data point on each flank of the anomaly. The calculation requires multiple data values at one or more locations on che map or a subjective estimate of the variance of the data. It is assumed that the variance of the data does not change from place to place on the map and that the recorded data values are normally distributed about the true value.

Notes: Studies of limestone hydrology have largely ignored the possible significance of water not flowing in major conduits. This component is designated “percolation water.” The importance of percolation water in an area is probably a function of rock type, structure and hydrologic characteristics. Experiments undertaken in England and Jamaica tracing percolation water with the dyestuff Pyranine Conc. suggest longer flow-through times than for water sinking at discrete points on the surface (allogenic water). The soil cover in an area may be in part responsible for this delay. Results from percolation water traces may be used to compile isochronal maps of limestone catchments.

Notes: For several years resistance-capacitance networks have been used to simulate aquifers. Most reported work has been concerned with fast time analogues in which the period under consideracign is represented in micro-seconds. However the alternative slow time analogue has many advan tages since the electrical experiment takes several seconds. This results in simpler equipment and simpler experimental techniques.The paper concentrates on the practical aspects or the slow time analogue giving details of the components, describing a method of simulating wells and recharge and comparing measuring instruments. The techniques are illustrated by a simplified example.

Notes: Insights into the chemical and Hydrogeologie history of spring waters in carbonate rocks can be gained from a study of the chemical quality of such waters and of the waters which feed springs. The median Ca2+/Mg2+ ratio was 3.4 in 29 spring waters from folded and faulted carbonate rocks near State College, Pennsylvania, indicating ground-water flow predominantly in limestone. The mean dissolved oxygen content was 7.7 mg/1 or 71% of saturation consistent with subsurface flow chiefly under water table conditions. Most of the dissolved solids (as specific conductance) including pollutants such as Cl and NO3 were added to spring waters during ground-water flow. Specific conductances ranged from 180 to 476 micromhos, with a mean of 347 micromhos. CO2 pressures were from 10−1.9 to 10−2.6 atm with a mean of 10−2.2. atm. The CO2, which is chiefly introduced as gas by downward diffusion from the soil zone, gives spring waters the capacity to hold about 3 times more hardness and alkalinity than streams in equilibrium with the atmosphere. However, all spring waters were undersaturated with respect to calcite and dolomite because of their short residence times as ground water. Dye tracing of ground-water feeding springs in two drainage basins gave residence times of 2–6 days for subsurface flows of about 4,000 feet. The specific conductance and carbonate saturation data indicate that ground-water residence times of the 29 spring waters average somewhat longer than 2–6 days.

Notes: Reliable prediction of the yield of infiltration galleries can be made only on the basis of careful field testing combined with evaluation of surface flow-duration data. While extensive pump testing is often relatively expensive the information obtained indicates the long-term utility of the system. Pump test procedures and methods of analysis are outlined.With proper design much wider utilization can be made of infiltration galleries than is presently done. The long life and low maintenance requirements are particularly favorable for small systems. Design and maintenance suggestions are made for successful operations.

Notes: In the Maumee River Basin of northwestern Ohio the principal source of ground water is the Silurian-Devonian carbonate aquifer. The use rate of ground water from this aquifer could rapidly increase many fold in the near future. This situation demands quantitative information on the resource potential of the aquifer, if proper development is to be encouraged.A relationship between ground-water use and recharge rates through an analysis of the cones of influence is demonstrated in this paper. Computed recharge rates for the cones of influence vary from 6,800 to 75,300 gpd/sq mi, and the variation is systematic in that the higher recharge rates correlate with the higher pumpage rates. Recharge rates appear to have an upper limit of approximately 100,000 gpd/ sq mi, which corresponds to a maximization of the vertical hydraulic gradient. Although maximization of the vertical hydraulic gradient is impossible to achieve for a given cone of influence, it can be approached by lowering the piezometric surface of the aquifer by increasing the pumpage rate.Assuming that the safe yield of an aquifer is equivalent to the rate of recharge, this study demonstrates that development of an aquifer can increase many times its potential.

Notes: An extensive program of electric well logging has been conducted in Hawaii during the past three years to determine the applicability of this tool to the volcanic environment which exists in Hawaii. Electric well logging techniques were found to be useful in Hawaiian basaltic aquifers; however interpretation of both spontaneous potential logs and resistivity logs varies from the conventional interpretation of electric logs in sediments. The interpretation of fluid conductivity logs in Hawaii follows conventional water well techniques.The analysis of spontaneous potential and resistivity well logging in basalts, which constitute most of the Hawaiian aquifers, poses problems because of the relatively uniform composition of the basalts and the complex relation of porosity to resistivity in basaltic aquifers, and because logging usually is performed in water-filled boreholes. Spontaneous potentials are thought to result primarily from fluid flow rather than from electrochemical potential, and positive SPs generally indicate zones with flow from the aquifers into the well, and negative SPs generally indicate zones with little flow or flow from the well into the aquifer. Resistivity logs indicate the location, number, individual thickness, and total thicknesses of permeable and less permeable formations, and are useful as indicators of water-yielding zones. High resistivities generally are indicative of dense impermeable basalts and low resistivities are indicative of porous permeable zones most likely to contribute water to the borehole. Both resistivity and spontaneous potential logs provide a direct measurement of depth to water, depth of casing, and depth of hole.

Notes: The salinity and nitrate content of well water for an urban zone (Fresno-Clovis, California) and the immediate surrounding irrigated agricultural zone were compared using data for 1950 through 1967. Time trends in these water chemical properties were evaluated statistically by dividing the 18-year period into three 6-year periods. Salinity of the urban zone ground water has increased with time, whereas that of the agricultural zone has fluctuated considerably. Possible reasons for changes are discussed. The nitrate content of well water from both zones has increased with time, with water from the agricultural zone showing the greatest increase. Key words; ground-water degradation; salinity; nitrate.

Notes: A break in a waste-discharge line associated with a 49-foot rise in stage of the Ohio River in March 1967 allowed an undetermined volume of 22 percent hydrochloric acid to enter the Pleistocene outwash aquifer used by a Kentucky industry. Chloride concentrations in excess of 30,000 mg/l (milligrams per liter) were observed in the water discharged from the industrial well nearest the break in the waste-discharge line. Chlorides ranged from 5–26 mg/l in water pumped from this area prior to intensive development. Other changes in water chemistry such as an increase in iron from 5 mg/l to 9,600 mg/1 indicate a dissolution of the aquifer materials. Movement of the highly mineralized water in response to river stage and pumping of the industrial wells has forced the industry to change its water-supply system. Three wells, approximately 600 feet from the river, were the primary water source prior to March 1967. By March 1968, the well nearest the acid source was abandoned, the remaining two wells near the river were used in a supplemental capacity and a fourth well 1,500 feet from the river plus a new well were the primary water sources. Fluctuations of chlorides in an industrial well near the river for a 16-month period indicate a persistent body of highly miner alized water near the acid source. Movement of this water body appears to be regulated at low river stages by the inclined surface of the New Albany Shale bedrock.

Notes: This paper deals with the ground-water flow into a drilled well, consisting of a vertical shaft and radially spaced horizontal intake pipes.It is based on model tests, devised and executed by the author in the Hydraulic Laboratory of the Haile Selassie I University in Addis Ababa, Ethiopia.The author tested the assumption of linearly distributed inflow into the pipes, based on the steady-flow theory of Darcy-Thiem, and found satisfactory agreement between theory and experiment.

Notes: A research project “Hydrologic and Other Aspects of Water Laws in Minnesota,” was conducted by the authors during the period July 1, 1967 through June 30, 1969 (see Walton and others, 1968, and Haik and others, 1969). The project was supported by funds provided by the U. S. Department of the Interior as authorized under the Water Resources Research Act of 1964 (Public Law 88–379).The project was concerned with: a compilation and analysis of the numerous codified and uncodified legislative laws, major court decisions, federal legislation, and ordinances of villages and cities bearing on water and related land resources in Minnesota. This paper briefly summarizes, without citation, the results of the research and presents the authors' views on the following subjects: state water resources administration, water policies as expressed in Minnesota's laws, problems associated with differing scientific and legal classifications of water, conflicting objectives of major resource agencies, provincialism and precedent in court decisions, insecurity of existing water rights, the adequacy of current legislation regulating water permits, the adequacy of the existing riparian doctrine of water rights, conflicts of federal-state jurisdiction, and constraints on development and management of water and related land resources in Minnesota.

Notes: The engine of a field vehicle can easily be used as an air pump by inserting a commercially manufactured check valve into a spark-plug socket. Small-diameter piezometers can be pumped with compressed air from this source. With sufficient air-line submergence, the air lift method can be used to pump 1-inch diameter piezometers where the pumping lift is less than 70 feet and 1.25-inch diameter piezometers where the pumping lift is less than 50 feet. In cases where this method will not work, some of the water contained in a piezometer can be pumped out by pressurizing the piezometer if the formation transmissivity is low and the pumping lift is not excessive. The maximum pumping lift is a function of the rate at which pressure in the piezometer is increased and the rate at which water flows into the formation with increasing head in the piezometer.The engine air pump is useful in developing piezometers, flushing out stagnant water before taking water samples, obtaining water samples, and creating head differences to initiate slug tests.

Notes: Increased irrigation demands on water from the Platte River in central Nebraska are causing a depletion in the flow that passes the City of Lincoln's Municipal well field, at Ashland, Nebraska. A study was made for the U. S. Army Engineers, Omaha District as to the future harmful effects of this depletion.a mathematical model using the Theis nonequilibrium equation was formulated. Drawdown computations were performed using an IBM 360 Model 65 computer. Recharging image wells were used to represent the physical boundary of the aquifer. Drawdowns in selected wells were calculated using the method of superposition by including both the real wells and the image wells. Values for permeability and the storage coefficient were computed from field pumping test data.Three different model runs were made. First, the wells were assumed to be pumped continuously at maximum output of 84 M.G.D. for periods of 10, 30, and 60 days both with and without river recharge.Next, the same time periods and recharge situations were run assuming 37 wells to be operating at their present field capacities, totaling 60 M.G.D.The third computer run was made using 39 wells. During the first 10-day period only 27 wells were modeled to produce 51 M.G.D. In the next 10 days 31 wells were required to produce 59 M.G.D., and finally for the last 10 days 20 wells were-used to produce 37 M.G.D. This operation duplicated the actual operation for July, 1968, when the all-time peak production for any one month was recorded.It is concluded that the well field can be operated at high rates for periods of greater than 30 days without recharge from the river. Previous studies have indicated the river is the source of most of the water produced from the wells. The study does indicate that the well field can draw on the ground-water reservoir for much longer periods than had been assumed in the past.

Notes: Acid mine drainage is a serious problem in the Appalachian region. Coal mining has disturbed the natural ground flow system. The mines are continuously being flushed by this disturbed flow system and producing enormous quantity of sulphuric acid. A study of McDaniel Mine has revealed that the flow is lateral and clay layers under the coal do not allow it to leak into the underlying aquifer. A study of water well logs within 10 miles of Todd Mine revealed the existence of three separate aquifers. A pilot plan for Todd Mine is proposed to discharge the uncontaminated water from the upper aquifer to the lower aquifer under the concept of “weeping wells.” The acid discharge from the mine may be stopped. The extension of this scheme may solve the serious problem of pollution of Lake Hope. The concept may further be extended to other areas of the Appalachian region to control acid mine pollution.

Notes: A technique is presented for simulating partially penetrating rivers on two dimensional resistance-capacitance network analogue aquifer models. The method is tested against an analytic solution due to Boulton (1942). Several results are presented which can be used to estimate an approximate value for the steady state discharge of a well pumping near to a partially penetrating river.

Notes: This report is the result of a request by the State Board of Examiners of Water Well and Pump Installation Contractors. The Board is in the process of formulating a more reasonable set of guidelines which control the location of wells designed to produce water for human consumption and/or food processing with respect to potential or existing sources of ground-water pollution.The pollution of ground-water supplies is artfully treacherous. It appears belatedly and often is not recognized until a relatively large area has been contaminated and perhaps one or more individual water supplies have been rendered unfit for human consumption. It is known that soils and aquifer materials have capacity to remove or “filter” some types of contaminants, and something is also known of the limitations in this regard. It is with these thoughts upon which this report is based. The report is designed to briefly describe the results of several pertinent ground-water pollution investigations and present current and potential standards for governing “safe distances” between domestic-food processing wells and sources of potential or existing pollution. The recommendations are meant to emphasize the fact that no one set of distances are adequate and reasonable for ALL conditions. Whenever possible the “safe-distance” between a subject well and a source of potential or existing pollution should be based on local conditions.It is important that we develop knowledge that will permit continued use of the soil mantle as a waste-water treatment system and at the same time permit continued use of ground water for human consumption and/or food processing. Functional legal, administrative and engineering mechanisms must be developed to maintain this combined usage.The Colorado Board of Examiners of Water Well Drilling and Pump Installation Contractors was established in early 1968. By October the Board adapted a set of rules and regulations which provide minimum standards for location, construction, modification or repair of pumping equipment.The Board's current concern is with the sanitary quality of those waters which are to be used for domestic purposes; in particular. human consumption. Realizing that proper sanitary protection of domestic wells involves the prevention of the intake of contaminants, the Board of Examiners introduced a set of standards which provides for the location of wells and well casings with respect to sources of contamination. The standards were chosen arbitrarily and do not consider the differences between chemical and biological contaminants.It is the purpose of this report to briefly point out some of the past and current developments regarding the nature of ground-water pollution and, in particular, data related to studies of the length of travel of bacteria and virus-laden water when injected on both soil surfaces and in water wells.Two distinctly different aspects of pollution travel are considered. They are: (1) the movement of bacteria and viruses downward with percolating water; and (2) the lateral movement of identical pollutants once they have reached the zone of saturation.

Notes: Seismic methods, combined with available well and geologic data, were used to define the subsurface hydrologic and geologic conditions of the Walnut Gulch Experimental Watershed, a deep, alluvial basin near Tombstone, Arizona. Surface geology of the valley indicates an alluvium-filled area between igneous intrusives and sedimentary rocks that support the Tombstone Hills on che southwest and the Dragoon Mountains on the northeast. Seismic determinations revealed depths to the water table ranging from near zero at the confluence of Walnut Gulch and the San Pedro River to 475 feet in the central portion of the watershed. The accuracy of predicting the depth to either ground water or basement was ± 6 percent, while that for ground water alone was ± 10 percent.Seismic refraction methods failed to produce satisfactory results when certain conditions or combinations of conditions existed. The great depths of alluvium created the problem of estimating the seismic traverse length necessary to accurately determine the alluvium-basement interface. Increased compaction of alluvium with depth causes additional interpretation difficulties in some areas. Also, water-table elevation may not always be accurately determined if it is located above, and close to, a highervelocity layer.A minimum of gravity or well log information greatly increases the reliability of seismic information in these problem cases. Other methods may still be necessary to substantiate the seismic data obtained under these conditions.

Notes: Two stable finite difference schemes are presented for the numerical solution of the nonlinear partial differential equation describing the radial flow of soil moisture. The nonlinearity is due to the fact that the soil moisture diffusivity, D, is a nonconstant function of the nondimensional soil moisture, y. Numerical solutions for twenty-one different moisture dependent diffusivities are obtained. These diffusivities have the following forms: (a) eleven of the diffusivities represent flow into a sink, and the other ten represent flow from a source; (b) D is proportional to yP, where p =¼, ⅓, ½, 1, 2, 3, 4; (c) D is proportional to Ay, where A is a positive constant; and (d) some of the D's possess inflection points as y varies from 0 to 1. From these numerical solutions quantitative results are obtained for the following: (1) the boundedness and monotonicity of the moisture distribution; (2) the continuous dependence of the moisture distribution on the system's parameter, namely, the diffusivity; (3) the rate at which the “wetting front” approaches the steady state solution; (4) the evolution of the moisture front with time and with the formulation of the diffusivity; and (5) the time evolution of the rate of inflow or outflow at the wall of the source or sink.

Notes: The knowledge of aquifer parameters is invaluable for quantitative description of geohydrologic systems and for optimal utilization of ground-water resources. The classical methods of pumping-test analysis are mostly graphical in nature and there is room for error in individual judgment in the geographical analysis. The computer method for aquifer evaluation comes under the inverse analysis techniques and is based on the classical principle of least squares. The sum of the weighted squares of differences between the observed drawdowns and the drawdowns calculated using the theoretical drawdown equations for the flow system under consideration is minimized, treating the aquifer parameters as decision variables. The method can be applied to any flow system for which analytical expressions for the potential distribution are known. The method was successfully applied to four pumping tests, two in nonleaky confined flow 1 systems, one in a leaky confined flow system, and one in an anisotropic nonleaky confined flow system. The percentage differences between the values of storativity and of transmissivity arrived at by the two methods are found to be as much as 24-and 1.6 percents, respectively.

Notes: Alluvial faults are generally treated as impermeable boundaries. Recent investigations of the faults in Califoria's Owens Valley, however, reveal that they are semi-pervious, or leaky in nature. The rate of ground-water movement through a semi-pervious alluvial fault is dependent upon the hydraulic conductivity of the fault gouge, the thickness of this zone, and the water-level differential across the fault. Optimization of the ground-water resources in the Owens Valley is currently being practiced using these faults in a controlled RECHARGE-EXTRACTION-SALVAGE System. In a system of this type, artificial recharge is induced into the Valley's aquifers upgradient from alluvial fault zones by impounding and diverting the creek flow tributary to the area. Extraction of ground water is effected by means of large-diameter supply wells located near the faults on the upstream side. Salvage of ground water is accomplished by lowering the water table in the vicinity of these faults, thereby causing phreatic growth to die out. When predicting water levels in the vicinity of semi-pervious faults, a solution is obtained for the induced water-level decline caused by backward leakage through the faults.

Notes: The true velocity, V, of ground water at a point in the ground-water system may be expressed as the sum of a number of partial velocities labeled V1, V2, V3, et cetera. Each partial velocity may be denned as a velocity which results from the presence of certain features of the configuration of the water table. Partial velocities may be used to facilitate the discussion of ground-water flow systems and associated phenomena.

Notes: This paper presents some of the more common errors made in the development of ground-water supplies in the alluvial aquifers along the Ohio River in Kentucky. Ample available literature on proper methods of development of the alluvial aquifers generally seems to have been ignored by the water users in the area. The more common errors made in the typical developments are singled out for discussion.In the typical development the aquifer is treated as an inexhaustible underground river. Wells generally are clustered in small areas remote from the Ohio River, and are likely to be located more for convenience and economy of pipeline or property access than for hydrologic considerations. It is hoped by highlighting these errors and showing alternative methods of development that proper development practices will be fostered.Stages in the development of two hypothetical groundwater aquifers in the Ohio River valley are shown by eight illustrations that stress the common errors made in development and alternative methods of development taking into account hydrologic considerations.

Notes: Scanning and transmission electron micrographs of various shales establish the close correlation between clay-flake orientation and fissility. The shales with the best fissility have the highest degree of preferred orientation. Randomness of clay flakes prevails in non-fissile claystones. The results suggest that the fabric of shales may result either from the deposition of dispersed clay or by the collapse of clay floccules after deposition.

Notes: Sand volcanoes have been found in three sedimentary associations in the Upper Carboniferous Bude Formation. In two of these associations they formed when the dewatering of fluidized sand beds, deposited from traction carpets, was temporarily inhibited by the deposition of overlying units. In the third association the volcanoes formed during the normal post-depositional compaction of fluidized, muddy, poorly sorted units deposited from subaqueous mudflows. While is seems that the tops of fluidized sand beds were characteristically sheared by a fairly powerful current immediately after being deposited, the waters above the recently deposited mudflow units were commonly stagnant, allowing sand volcano growth.

Notes: Pelitic rocks were followed from unmetamorphosed clays and marls of Upper Triassic and Lower Liassic to anchimetamorphosed phyllites of the Alpine border region in Switzerland. Phengite and Al-rich chlorite formed from mixed-layer illite/montmorillonite; pyrophyllite from kaolinite. For the formation of paragonite, the following sequence is proposed: irregular mixed-layer illite/montmorillonite → regular mixed-layer mica/montmorillonite → mixed-layer paragonite/phengite → paragonite.Besides the formation of new minerals in the transition zone (anchizone) between diagenesis and greenschist facies, other changes with increasing metamorphic grade are: the crystallinity of illite (in the sense of Kubler, 1967) increases, the intensity ratio 002/001 of the illite basal reflexions increases, 1Md illite changes to 2M1 phengite; the slates change colour from red to pink; the mean density increases; and textural changes due to reactions between clastic quartz and clay cement occur.

Notes: Fabrics of Tertiary shales from the Rhinegraben (southwestern Germany) were studied by methods for fine-particle measurement including grain-size distribution, porosity, pore-size distribution, and specific surface area.The most frequent pore radii (rm) are found to decrease with increasing overburden, this decrease in relation to porosity being more rapid in shales, which are cemented by carbonate. The specific surface area (Sg) is not affected by pressure down to a depth of approx. 1,000 m. With increasing compaction pressure the specific surface areas are found to decrease indicating a fusion of clay-mineral particles, which corresponds to the alteration of smectite minerals into 10-Å mica.The sorting index of pore-size distribution (Sop) remains constant throughout the shallow-burial range. Below 1,000 m the sorting index increases considerably. This effect is caused by the coarse non-clay components of the shales, since on both sides of a nearly isometric quartz grain, for instance, large pores may be kept open even under high compaction pressure. This effect is also indicated by the skewness of the pore-size distribution, which shifts from negative to positive values near 1,000 m of overburden. Above this level fine pores predominate while deeper the relatively coarse pores are more abundant.This study shows that the conventional mechanical model of a clay-mineral fabric reacting on overburden pressure is applicable to the shallow-burial range only. After mineral transformations have commenced, the fabrics loose their original grain-size distribution, so that their porosities are no longer controlled solely by mechanical effects. With the Rhinegraben shales the shallow-burial range is limited to a depth of about 1,000 m.

Notes: Phyllosilicates and zeolites grew in Columbia River sediments during hydrothermal experiments at relatively low temperatures and pressures. Although the new minerals may not be equilibrium assemblages, our results strongly support the idea that matrix minerals in graywackes may be the result of alteration of components thermodynamically unstable in the environment of diagenesis. Scanning electron micrographs show that the new minerals have formed as a mesh-like coating on original grains. The textural relationship of the new minerals to the original minerals resembles graywacke texture.

Notes: Experimental investigation shows that amorphous silica is converted into quartz through cristobalite under hydrothermal conditions. The rate of transformation, essentially dependent on the reaction temperature, was studied on the basis of quantitative analyses of quartz in the products, and the variation of quartz content was elucidated by taking the induction period into consideration. The transformation is a consecutive reaction involving two first-order steps, from amorphous silica to low-cristobalite and from low-cristobalite to low-quartz. Kinetic data such as the rate constants and the energy of activation are obtained.Mineralogical varieties of silica found in siliceous deposits suggest that the transformation probably takes place under natural conditions. Younger deposits contain amorphous silica or cristobalite, whereas older ones are invariably composed of quartz. By assuming that the transformation process observed experimentally holds in nature, kinetic data can be estimated. Since the process depends upon the thermal history, it is possible to follow the transformation process for a given model of a thermal history. An example of computed results is compared with the geological evidence, and it is concluded that the mineralogical variation of silica is accounted for by the transformation process.Zonal distribution of silica minerals apparently corresponds to that of zeolite minerals, and the transformation of silica is considered to occur during diagenesis. Evidently, almost all diagenetic facies represent intermediate stages on the way to the ultimate equilibrium. The cristobalite stage described in this paper belongs to one of these stages, and is referable to the early stage of diagenesis. It is suggested that silica minerals can be used as clues to understand a progressive change in diagenesis.

Notes: The Ranger Canyon and Mowitch Formations are the youngest Permian strata in the Rocky Mountain Front Ranges. They constitute a thin, widespread and clearly defined stratigraphic entity covering approximately 60,000 sq. miles; they occur below Triassic beds and above a major, regional, intra-Permian unconformity, initiated by a transgression which started in the northwest. Beds of the above entity are therefore diachronous. The erosion surface is overlain by polymict, phosphatic conglomerates containing mature lag gravels and immature breccio-conglomerates and corrosion breccias.Rock types are either sandstones or silty and sandy cherts, phosphorites and occasionally dolomites. Clastic components are dominantly mature quartz (some pseudomorphs gypsum), phosphate, some feldspar, negligible clay, and stable detrital minerals, necessitating: (1) many cycled, clastic sedimentary rock; (2) local gypsum; and (3) phosphate producing, distributive provinces.Secondary features include primary cementation by quartz, chalcedony, dolomite, sulphate and phosphate, with replacement mainly by chalcedony. Contraction fractures are cemented by quartz (after anhydrite and fluorite), calcite and barite. Accessory authigenic minerals are hematite, sulphates (pseudomorphed by quartz), fluorite, apatite and dolomite. Diagenesis therefore occurred within a chemically active environment.Minerals present indicate: (1) phosphate producing and (2) evaporite producing environments, the components for which may be obtained from sea water by: (a) a biogeochemical phosphate-fixation cycle; and (b) concentration of brines by interstitial refluxion.A Recent environmental parallel occurs along the coast of Baja, California. Phosphate produced off-shore contributes to quartz-rich sediments prograding seawards; evaporitic conditions produce minimum carbonate and maximum sulphate precipitation.The sequence of events envisaged for the Permian rocks started with phosphate corrosion of bed-rock and cementation of lag gravels; some phosphate was contributed to shoreline, with quartz and gypsum sands, prograding over the basal conglomerate. Sand cementation by carbonate occurred in shoreline and intertidal zones, and by sulphate in the supratidal zones. Concentration of brines by refluxion, and local silica enrichment, facilitated silica precipitation and replacement. Penecontemporaneous silicification of Late Permian sediments was therefore instrumental in their ultimate preservation.

Notes: This paper presents the main trends in epigenetic research in the U.S.S.R. in the last years:〈list xml:id="l1" style="custom"〉1Study of epigenetic zonality in thick series of sedimentary rocks of various ages and tectonic regions, (zones of unaltered clay matrix, of altered clay matrix, of quartzitic structures and hydromica-chloritic cement, and of prick-like structures and phyllite-like schists).2Principles of stadial analysis and mineral indicators of different epigenetic stages (clay minerals, organic matter, zeolites, feldspars, sulfides).3Facies of regional epigenesis connecting the main petrographic families of unaltered terrigenic rocks (quartz sandstones with kaolinitic matrix and the same composition of associated clays, acidic arkoses with hydromicaceous clays, lithoclastic sands with several matrix components and associated clays, and volcanogenic greywackes) with “related” facies of regional metamorphism.4Some practical aspects of epigenesis are: for petroleum geology: maximum depth of burial according to porosity, interruption of quartz, feldspar, sphene, epidote, carbonate, biotite, and clay mineral epigenesis by oil migration; and for ore geology: (a) initial epigenesis: ore impregnation (e.g., volkonskoite in wood remains) due to intrastratal solution of heavy minerals and leaching of rock fragments; (b) deep epigenesis: e.g., galena impregnations due to release of trace elements during dissolution of rock forming minerals e.g., feldspars; and (c) metagenesis: “Alpine” veins across and along bedding, filled, e.g., with copper ores.

Notes: The paper describes a method for determining the time of formation of oil and gas accumulations on the basis of the number of epigenetic minerals contained in granular reservoir rocks. The beginning of the accumulation is established by comparing the epigenesis stage in the oil- or gas-bearing crest areas of the trap with the water-bearing part of the reservoir at different depths of the geological section. This takes into account that the epigenetic processes tend to intensify with depth and to slow down after the rocks become filled with hydrocarbons.The time of accumulation completion is found by comparing the degree of epigenetic alteration of the oil- and gas-bearing reservoirs with the water-bearing reservoirs occurring at the oil (gas)-water interface in the trap. The greater the differences, the older is the age of the pool completion. Lack of a difference indicates a youthful pool completion.In this paper, the ratio of detrital to authigenic titanium minerals, the quantity of regenerated quartz grains, and the pelitization of feldspars have been used.The application of this method is exemplified by oil deposits occurring in the productive Valangien and Hauterive beds (Lower Cretaceous) of the Ust-Balyk and Megion fields of western Siberia.

Notes: One of the productive horizons (17th) of north Sakhalin has been studied. The areas within and beyond oil and gas pools, near the top and at the flanks of structures were compared with areas where the horizon under study was waterbearing. The rocks were least transformed by secondary processes within oil accumulations, where a sudden increase was observed in the content of feldspars and accessory minerals (epidote, ilmenite and sphene) which had not undergone intrastratal solution. Inside gas pools, however, no deceleration of epigenesis has been observed. This points to a more recent (post-Pliocene) accumulation of gas, whereas the first oil migration in these Miocene strata occurred in the Upper Pliocene, according to the hampered epigenesis.

Notes: The results obtained by the author in the study of clay-minerals diagenesis are compared critically with the principal publications in this field, giving a general picture of the transformation of sheet silicates.Kaolinite minerals are related to the surficial zones of the earth's crust where they are formed. They are characterized by the hexacoordination of aluminium. They furnish paleogeographic indications in ancient sediments. During diagenesis they are very sensitive to the geochemical environment, stable in acid conditions, unstable in alkaline conditions. However, the increase in temperature by burial causes their destruction sooner or later. In the transitional zone to metamorphism (anchizone), kaolinite is not present. Only dickite and nacrite can be observed, provided that the environment is acid.Montmorillonites are hydrated minerals. The rise in temperature and above all in pressure during burial expels water from the interlayers. Concentrated interstitial solutions of diagenesis provide cations which replace molecules of water between the layers. It is an irreversible reaction which produces 14-Å minerals (chlorites) or 10-Å minerals (illites), passing generally through mixed-layer structures. The lack of montmorillonite is normal in formations which have undergone a marked burial.Mixed-layers are intermediate stages which occur during degradation by weathering and during aggradation by deep diagenesis. This aggradation is the result of an incorporation of certain cations taken up from interstitial solutions, and of a rearrangement within the lattice. There are two major pathways: a potassium and sodium pathway, which produces the illites, then the micas, passing possibly by regular mixed-layering of the allevardite-rectorite type; and a magnesium pathway, which produces the chlorites, passing possibly by a regular mixed-layering of the corrensite type. These mixed-layers can remain stable until the border of meta-morphism (anchizone).Micaceous clay minerals or illites form a very heterogenous group in the sediments which have been hardly diagenetized. Particles of diverse origin are found. They become more regular during burial. In deep diagenesis and the anchizone, crystallo-graphic parameters of the illite are sufficiently well defined to serve as a scale of recrystallization, a zoneographic index. The morphology of the particles changes. Polymorphic types 1Md and 1M are replaced by the 2M-type. The sharpness of the 10-Å peak, conventionally called “crystallinity”, is an interesting quantitative criterium, together with the intensity ratio of the 5-Å and 10-Å peaks, which is related to the chemical composition of the octahedral layer.Micas in low-grade metamorphism, called sericites by petrographers, replace the illites discussed above. They are different from the true micas by a weaker layer charge, less than 0.9 by half-cell. They often contain sodium (paragonitic muscovites and paragonites). The octahedral charge (zero for the muscovite) is generally high, due to the replacement of Al by Fe2+ and Mg (phengites). These transformations should not obscure the fact that metamorphism is also accompanied by crystalline growth and massive neoformation.Chlorites are the least well-known clay minerals in diagenesis. Detrital particles can be aggraded to chlorite during early diagenesis by passing through the mixed-layer stage of corrensite. A massive growth of chlorite is observed in late diagenesis and the anchizone. Illite and chlorite slates give place to sericite and chlorite schists. At present, general data are not available on the crystal chemistry of chlorites in the anchizone and the greenschist facies.The stages in the diagenetic evolution of clay minerals are too little understood to be able to give them precise limits. However, the following provisional scheme can be proposed:(1) Early diagenesis (= “diagenesis” of Russian authors; = the “shallow-burial stage” of Müller, 1967a). In this stage all the clay minerals are stable; some undergo aggradation by adsorption of Mg, K and Na (various mixed-layers); some are neoformed (montmorillonites).(2) Middle diagenesis (= “early catagenesis or epigenesis” of Russian authors; the “deep-burial stage” of Müller, 1967a, includes this stage and all the following until metamorphism). In this stage the sediment becomes compact. It has lost at least 50% of its connate water. Porosity is high and circulation still plays an essential part. Some detrital minerals, such as biotite, are unstable. All the clay minerals are still stable, but many types of replacement take place, due to interstitial circulation. Dickitization of kaolinite and illitization of montmorillonite can already be observed.(3) Deep or late diagenesis (= “late catagenesis or epigenesis” of Russian authors). In this stage the temperature is greater than 100 °C, pressure increases and porosity becomes very weak. Montmorillonites and irregular mixed-layers disappear. Kaolinite recrystallizes as dickite in acid environment. These changes are irreversible.(4) Anchizone (= “metagenesis” of Russian authors; = “zone anchimétamorphique” of Kubler, 1964). This is the transitional zone to metamorphism. It agrees with temperatures around 200 °C. Illite and chlorite are almost the only sheet silicates. However, dickite can be observed as well as pyrophyllite generally associated with allevardite. The crystallographic parameters of illite define the limit of the following zone, the metamorphic epizone or greenschist facies.The crystallochemical processes that take place during the diagenetic evolution of clay minerals are schematically the following:(1) Gradual tetracoordination of aluminium.(2) Filling of octahedral sites either by interlayer cations, either by cations derived from outside the lattice, without the distinction dioctahedral-trioctahedral becoming very clear.(3) Interlayer exchange between crystal lattice and interstitial solution. Gradual closing of the layers by alkaline cations or octahedral brucite-like sheets.(4) Massive crystalline growth in the anchizone and the epizone.These processes are roughly symmetrical with those which occur during weathering.This review is a summary of the conclusions drawn in a Docteur-ès-Sciences thesis (G. Dunoyer de Segonzac, 1969: Les Minéraux argileux dans la Diagenèse. Passage au Métamorphisme, 339 p., 45 tables, 110 illus.) to be published as part of the series Mémoires du Service de la Carte Géologique d'Alsace et de Lorraine. Most of the evidence on which these conclusions have been based is not cited directly in this article, but can be found in the thesis mentioned above, to which the reader is referred.

Notes: The paper presents the dynamics of the structural change of kaolinite and its polymorphous (polytype) modifications at different stages of sedimentary rock formation. Sedimentogenesis is characterized by a gradual disordering of structure of triclinic kaolinite, the degree of disorder produced being proportional to the intensity and duration of the influence of the hydrodynamic medium. Epigenesis (deep) is connected with gradual transformation of kaolinite into dickite through the stage of mixed-layer growths inheriting the structure of twin rotations of disordered kaolinite from the sedimentogenesis stage.In metagenesis filling of fissures with dickite or nacrite takes place. The former is peculiar to the general thermodynamic medium of deep epigenesis/metagen-esis, whereas nacrite is an indicator of intense stress and seems to be due to transformation of dickite.

Notes: In the course of deep weathering of a biotite gneiss, biotite is transformed into mixed-layer biotite-vermiculite hydrobiotite. Later biotite-vermiculite is transformed into biotite-chlorite under the action of hydrothermal solutions at the stage of epigenesis.

Notes: Experimental studies on saturation of montmorillonite with potassium showed that sorption of potassium tends to produce a regular alternation of the interlayer regions.The sorptive nature of the potassium fixation by montmorillonite appears to form the basis of the epigenetic formation of rectorite.

Notes: Relationships between crystal chemistry and genetic conditions are presented for a series of dioctahedral micaceous minerals. Using a ferruginicity index, three groups of micaceous minerals are distinguished: Al-micas, Fe-illites, and glauconites. The degree of Al-for-Si substitution in the tetrahedral sheets of micaceous minerals depends on their thermodynamic genetic conditions. If pressure and temperature increase, the Al-IV content increases and the octahedral sheet is “cleaned” from divalent cations. This process is accompanied by structural alteration with a polytype sequence 1Md-1M-2M1. Tetrahedral and octahedral charges are the same for micaceous minerals formed at the surface (sedimentogenesis/diagenesis) and are independent of the iron content. For most illites of sedimentary rocks an authigenic origin is suggested.

Notes: Precision measurements of the densities and the optical constants of authigenic low-temperature orthoclases, albites, muscovites and quartz, and comparisons with those of their high-temperature counterparts of identical or similar composition proved that the authigenic orthoclase and muscovite have significantly lower densities than the high-temperature modifications.For quartz and albite density differences are not established.The optical constants of the low-temperature minerals (except for quartz) likewise possess specific properties, manifested in the orientation of the optical indicatrix and the values of the angle 2V.

Notes: This paper describes a new equipment for investigating the density properties of minerals and rocks. A description is given of the principle and operation of a gravitation gradient tube, of density standards and of a device for the precise density determination and separation of minerals. The possibility of using the method described for geological and mineralogical studies is discussed.

Notes: The texture of carbonate cement in clastic rocks reflects the conditions of: (1) free pore crystallization; or (2) recrystallization under elevated temperatures and pressures. Fibrous carbonate cement may be formed as a result of preferential adsorption of clay particles or colloids in the direction perpendicular to c. Cryptocrystalline carbonate cement is formed in sandstones if the ratio carbonate/ argillaceous matter in less than 5 (for montmorillonite) or less than 3–4 (for illite), especially if it is near 2–1.The maximum amounts of isomorphic admixtures of Mg and Fe in calcite cement (see Fig.2) can be used for temperature reconstructions of the epigenetical environment.In deep-buried rocks which are almost closed systems, migration rates are lower than diffusion rates and microenvironments of detrital grain corrosion may exist adjacent to those of precipitation of the same mineral.

Notes: Based upon studies of natural quartz and upon laboratory experiments on mechanical and chemical destruction of quartz, it was established that the statistical density characteristics of detrital quartz change during sedimentary processes. Grains with defective structure, gas-liquid inclusions, inclusions of organic matter and other lighter minerals have lesser densities, whereas grains with inclusions of heavier minerals have larger densities than those of optically pure grains. The susceptibility to destruction is less for optically pure grains than for grains with lower or higher density. This is responsible for the increasing maturity of quartz sand during weathering and transport as indicated by the increasing percentage of optically pure grains. Mathematical modelling of the dynamics of this process was carried out.

Notes: The structure of multilayer polytype modifications of layer silicates may be regarded as the result of a combination of regularly oriented single layers. Accordingly, the optical constants of a single layer (of a monolayer polytype modification) may be used for the calculation of optical constants of any other multilayer polytype modification of a given type of layers.The formulas connecting the constants of a polytype modification of layer silicates have enabled the establishment of the main parameters (Ng, Nm, Np, 2V) of the muscovites 1M and 2M2 according to the known optical constants of the muscovite 2M1, and the computation of the new constants of kaolinite and nacrite based on the known parameters of dickite. The optical constants established theoretically were confirmed by direct measurements for muscovite 1M, muscovite 2M2 (gämbelite) and kaolinite. The optically positive character of kaolinite with +2V = 25° has been established.The assumption of the optical mixibility of finely dispersed polyminerallic media, in which the dimensions of monotype crystals are smaller than the visible light waves, made it possible to determine the quantitative relations of clay minerals in the mixtures based on optical constants of oriented aggregates.

Notes: The distinction of montmorillonite proper from beidellite is often based on the Li-test proposed by GREENE-KELLY (1953). However, when saturated with Li, true montmorillonite samples that contain considerable admixtures of SiO2 or Fe2O3hH2O behave in the same way as beidellites. An irreversible sorption of Li (after annealing at 250°C) is observed in such samples only after the admixed amorphous substance has been removed by leaching with a NaCO3 or HCI solution