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Showing papers in "Journal of Geophysical Research in 1962"


Journal ArticleDOI
TL;DR: In this article, a horizontally layered inhomogeneous medium is considered, whose properties are constant or nearly so when averaged over some vertical height l′, and conditions on the five elastic coefficients of a homogeneous transversely isotropic medium are derived which are necessary and sufficient for the medium to be "long-wave equivalent" to a horizontally-layered inhomogenous medium.
Abstract: A horizontally layered inhomogeneous medium, isotropic or transversely isotropic, is considered, whose properties are constant or nearly so when averaged over some vertical height l′. For waves longer than l′ the medium is shown to behave like a homogeneous, or nearly homogeneous, transversely isotropic medium whose density is the average density and whose elastic coefficients are algebraic combinations of averages of algebraic combinations of the elastic coefficients of the original medium. The nearly homogeneous medium is said to be ‘long-wave equivalent’ to the original medium. Conditions on the five elastic coefficients of a homogeneous transversely isotropic medium are derived which are necessary and sufficient for the medium to be ‘long-wave equivalent’ to a horizontally layered isotropic medium. Further conditions are also derived which are necessary and sufficient for the homogeneous medium to be ‘long-wave equivalent’ to a horizontally layered isotropic medium consisting of only two different homogeneous isotropic materials. Except in singular cases, if the latter two-layered medium exists at all, its proportions and elastic coefficients are uniquely determined by the elastic coefficients of the homogeneous transversely isotropic medium. The observed variations in crustal P-wave velocity with depth, obtained from well logs, are shown to be large enough to explain some of the observed crustal anisotropies as due to layering of isotropic material.

1,585 citations


Journal ArticleDOI
TL;DR: In this paper, three forms of the Kramers-Kronig type of dispersion equation are presented, and the absorption coefficient has a linear dependence upon frequency for frequencies above a certain characteristic value, chosen low enough to be outside the range of measurement.
Abstract: Although the attenuation of body waves in an infinite medium has often been considered, little emphasis is usually given to the attendant dispersion, which is a necessary consequence of the medium absorption and is determined unambiguously by it. Dispersion equations are obtained from the application of an integral transform in the frequency domain. Such relations are of the Kramers-Kronig type, relating the dispersive part of the index of refraction of the medium to the absorptive part by means of an integral over the entire frequency range. They are a consequence of the principle of causality and follow without recourse to a specific wave equation. In particular, our results are consistent with and presume linearity for the wave motion. Three forms of the dispersion equation are exhibited. In all cases, the absorption coefficient has a linear dependence upon frequency for frequencies above a certain characteristic value—chosen low enough to be outside the range of measurement. However, it is necessary in all cases to introduce a low-frequency, nonzero cutoff for the absorption, which can in principle be taken arbitrarily small. Group and phase velocities are determined as functions of the medium Q and a characteristic velocity, which for small absorption can be related to the measured signal velocity. Seismic phenomena occur in materials where the absorption is small, Q≥30, so that the corresponding dispersion presumably will be difficult to measure in the earth. For appropriate laboratory materials the effect can be significant.

1,080 citations


Journal ArticleDOI
TL;DR: In this article, the problem of the approach to the geostrophic wind is solved assuming that the exchange coefficient is proportional to the one-third power of the rate of dissipation of turbulent energy.
Abstract: The problem of the approach to the geostrophic wind is solved assuming that the exchange coefficient is proportional to the one-third power of the rate of dissipation of turbulent energy. Reasonable agreement between the predicted and observed values of the surface stress, surface wind direction, and height of the layer of frictional influence is obtained when the size of the eddies is assumed to become independent of height at a relatively low level. The predicted vertical distribution of exchange coefficient is qualitatively in good agreement with that observed at Leipzig.

899 citations


Journal ArticleDOI
TL;DR: In this paper, a cross-sectional distribution of the fluid potential in a basin of homogeneous lithology is found, and a boundary between areas of recharge and discharge is proved mathematically.
Abstract: On the basis of the parallel pattern of the water divides and the valleys in parts of central Alberta and the inferred difference in permeability between the Paskapoo and Edmonton formations, basins are considered to be separate units of flow in the groundwater regime. For the cross-sectional distribution of the fluid potential in a basin of homogeneous lithology an equation is found that relates the fluid potential to the acceleration of gravity, topographic gradient of the valley flank, horizontal distance between water divide and valley bottom, elevation of the water table at the valley bottom above the horizontal impermeable boundary, elevation above the horizontal impermeable boundary, and horizontal distance from the valley bottom. The validity of the assumption that groundwater runoff is discharged mainly at the valley bottoms is disputed. A boundary between areas of recharge and discharge is proved mathematically. A theory is advanced to explain the systematic deviation of the theoretical value of the fluid potential from the observed values. Local anomalies of the piezometric surface are accounted for by the presence of lenticular bodies of relatively high permeability. Mathematical formulas are used to express the relation between those anomalies and the permeability ratios and the size and shape of the lenses. A schematic cross section of possible potential distribution and flow pattern across a watershed is presented.

442 citations


Journal ArticleDOI
TL;DR: In this paper, a computer program has been written to calculate normalized surface displacements as functions of horizontal phase velocity (or angle of incidence) and wave period in a single-layer model of the continental crust.
Abstract: Expressions in terms of layer matrices have been derived for the motion of the free surface when plane harmonic P or SV waves are incident at any given angle at the base of a horizontally layered crust. A computer program has been written to calculate normalized surface displacements as functions of horizontal phase velocity (or angle of incidence) and wave period. Numerical values have been obtained for the same single-layered model of the continental crust for which the corresponding calculations for SH waves have been presented previously. The surface motion pattern is similar to that of the SH case, but it is somewhat more complex owing to PS and SP conversions at the layer boundaries. Variations in amplitude and phase of the surface displacements are particularly large and erratic in the case of SV waves that are incident at angles such that α1 αn, the crustal transfer functions for incident SH and SV waves are sufficiently similar for conventional methods to be used in determining the angle of polarization with moderate accuracy.

352 citations


Journal ArticleDOI
TL;DR: In this paper, a model of axisymmetric turbulence over an infinite plane involving only one "external parameter" the turbulent heat flux is proposed. And the influence of compressibility and of the delayed interaction of flow patterns propagating with sound velocity has not been studied sufficiently.
Abstract: The specific features of atmospheric turbulence can hardly be observed in the laboratory and should be studied in the atmosphere, where the range of scales of disturbances is very broad. Slow fluctuations in energy dissipation which are due to the change of largescale processes (weather in a general sense) can be taken into consideration approximately by ‘statistical mixing’ (by using superposition) of various regimes. The analysis of the simplest schemes shows that some numerical ‘constants’ in particular Kolmogoroff's 2/3 law coefficient for a mixed regime, are, in general, functions of the external parameters of a flux (e.g., Reynolds number). Thermal inhomogeneity of the atmosphere and the resulting buoyancy are of importance as factors initiating turbulence and often become the dominant ones. To describe the turbulent structure under fully developed convection, we may suggest the model of axisymmetric turbulence over an infinite plane involving only one ‘external parameter’ the turbulent heat flux. The influence of compressibility and of the delayed interaction of flow patterns propagating with sound velocity has not been studied sufficiently. We may assume that the conditions are more favorable for studies of acoustical noise accompanying the turbulence itself (vorticity component of the velocity field) in the atmosphere than in wind tunnels. Therefore, the study of the frequency spectrum of small oscillations of a compressible stably stratified atmosphere may be of some interest.

339 citations


Journal ArticleDOI
TL;DR: In this article, it is suggested that the low-velocity zone is caused by downward transition from the sub-Mohorovicic peridotite into plagioclase pyrolite, which has a relatively low seismic velocity.
Abstract: The occurrence of a low-velocity zone in the upper mantle has been attributed to the effect of high temperature gradients. If the upper mantle is homogeneous, it is shown that the required temperature gradients would lead to extensive melting. Since this consequence is unacceptable, it appears necessary to consider nonhomogeneous models. It is assumed that the mantle immediately below the Mohorovicic discontinuity consists dominantly of dunite and peridotite. This passes downward into more primitive material, which is chemically equivalent to a mixture of 1 part of basalt to 4 parts of dunite. For convenience, this hypothetical primitive material is called ‘pyrolite.’ Within the upper mantle, the pyrolite might occur in either of two principal mineral facies—(i) as the assemblage olivine-pyroxene-plagioclase (plagioclase pyrolite) and (ii) as the assemblage olivine-pyroxene-garnet (garnet pyrolite). There would also be a substantial transition zone between these facies, in which olivine, pyroxene, plagioclase, and garnet coexisted. It is suggested that the low-velocity zone is caused by downward transition from the sub-Mohorovicic peridotite into plagioclase pyrolite (which has a relatively low seismic velocity) and then into garnet pyrolite. The low-velocity zone is thus due to the presence of plagioclase as a primary phase. Further aspects of this model are explored. The depths of these various zones probably differ between oceanic, continental margin, and Precambrian shield regions. The model implies that a low-velocity zone may not be present beneath Precambrian shields. In regions which have been recently subjected to diastrophism, the characteristic geotherm may pass for a considerable distance through the transition zone between plagioclase and garnet pyrolite facies. This can give rise to acute thermal and mechanical instability, which may in turn cause diastrophism in the crust. Evolutionary relationships between oceanic, active orogenic, and Precambrian shield regions are also discussed in terms of the model.

307 citations



Journal ArticleDOI
TL;DR: The magnetic ellipsoids of a number of Tertiary lava flows, banded gabbros, dikes, cone sheets, a ring dike, and Precambrian basic gneiss have been determined as discussed by the authors.
Abstract: The anisotropy of magnetic susceptibility of some basic igneous and metamorphic rocks has been found to be due to the preferred orientation of the long axes of grains of magnetite. The degree of anisotropy is in a few samples as great as 40 per cent but usually is less than 10 per cent. The variation in anisotropy is believed to be due to variation in the degree of preferred orientation, and in susceptibility due to grain size and chemical composition. Half of the susceptibility ellipsoids determined were found to approach an oblate shape while only a quarter of the remainder approached prolate shapes. The magnetic ellipsoids of a number of Tertiary lava flows, banded gabbros, dikes, cone sheets, a ring dike, and Precambrian basic gneiss have been determined. The principal susceptibility directions of most of the lavas were widely dispersed but in some flows were tightly grouped—the minima round the pole of the flow plane, the maxima normal to the flow direction in the flow plane, and the intermediates in the flow direction. Similar groupings were found with the banded gabbros but not with the other intrusives. Basic gneisses show a very marked concentration of maxima in the direction of the visible lineations and of minima normal to the observed foliation. The applicability of anisotropy measurements in structural petrology is discussed.

251 citations


Journal ArticleDOI
TL;DR: A detailed description of the cosmic ray experiment on Explorer 12 is given and cosmic ray measurements made during the solar event of September 28, 1961, are reported and discussed in this article, where the history of the intensity of the solar protons is consistent, once isotropy is established, with their having diffused through interplanetary space with an effective mean free path of 0.04 AU.
Abstract: A full description of the cosmic ray experiment on Explorer 12 is given and cosmic ray measurements made during the solar event of September 28, 1961, are reported and discussed. Galactic cosmic ray measurements are also reported. A few hours before the class 3 flare of September 28, two short counting rate increases were observed and are interpreted as electron bursts. The anisotropy of the medium- and low-energy solar protons early in the event and their intensity throughout the event are described. It is found that the history of the intensity of the solar protons is consistent, once isotropy is established, with their having diffused through interplanetary space with an effective mean free path of 0.04 AU. This result is discussed and is shown to be not obviously in disagreement with the generally accepted views regarding the configuration of the interplanetary magnetic field. An estimate of the distance from the sun at which diffusion becomes unimportant and particles escape gives 2 to 3 AU. It is pointed out that simple diffusion (where the particles are scattered from discrete scattering centers and the influence of a general magnetic field is negligible) does not account for the behavior of the anisotropy before isotropy is reached. Two days after the flare, and beginning just before the sudden commencement of a magnetic storm, there was a large increase in the intensity of protons between 2 and 15 Mev, the lower energy limit being determined by the sensitivity of the detectors. As most of these particles, which we have called ‘energetic storm particles,’ arrived after the sudden commencement occurred, we suggest that they were solar protons trapped within the plasma cloud which caused the magnetic storm. The outline of a possible trapping mechanism is given. Explorer 12 measurements of the Forbush decrease of September 30, 1961, are compared with neutron monitor measurements at Deep River. The decrease is larger at Explorer 12 by a factor of 1.7±0.3.

230 citations


Journal ArticleDOI
TL;DR: In this article, laboratory measurements on sediment suspensions, settling rates, rheological properties and deposition from flowing water showed a dependence of the mode of transport on the suspended sediment concentration and on flocculation kinetics.
Abstract: Laboratory measurements were made on properties of clay sediments from San Francisco Bay, in conjunction with field measurements, to ascertain the modes of transport and deposition existing in the bay. Laboratory measurements on sediment suspensions, settling rates, rheological properties, and deposition from flowing water showed a dependence of the mode of transport on the suspended sediment concentration and on flocculation kinetics. These qualitative relations are supported by tracer observations of sediment transport processes in the bay.

Journal ArticleDOI
TL;DR: In this paper, the wave amplitude distribution and wave amplification rate of the laminar boundary layer along a concave wall are analyzed. But the mechanism by which the wave number is determined remains an open question.
Abstract: Velocity measurements in the boundary layer along a concave wall reveal a spanwise variation having a definite wave number whether the boundary layer is laminar or turbulent. The variation is interpreted as produced by a system of vortices with axis in the streamwise direction. For the laminar boundary layer the vortices are identified with those predicted by the theory of laminar instability. The wave amplitude distribution and wave amplification rate are in good agreement with the theoretical prediction. For the turbulent boundary layer the concept of eddy viscosity is introduced to account for the observed phenomena by the theory of laminar instability. In both cases, however, the mechanism by which the wave number is determined remains an open question. Since the centrifugal force in the concavely curved boundary layer is analogous to the buoyant force in the thermally stratified boundary layer in giving rise to instability, some analogous phenomena may be expected in the boundary layer along a heated horizontal wall.

Journal ArticleDOI
TL;DR: In this article, the authors reviewed the nature of the transition zone in the mantle between about 300 and 900 km and found that pyroxene will break down to a denser assemblage of olivine plus stishovite (the rutile polymorph of SiO2) around 400 km.
Abstract: The nature of the transition zone in the mantle between about 300 and 900 km is reviewed in the light of recent high-pressure experimental results. Under the P-T conditions existing in the mantle it is found that pyroxene will break down to a denser assemblage of olivine plus stishovite (the rutile polymorph of SiO2) around 400 km. In the vicinity of 600 km the olivine inverts to a spinel structure, with a further increase in density. Finally, between 900 and 1050 km, the spinel breaks down into denser, close-packed phases, which persist to the core boundary at 2900 km. Two transformations are possible: (a) spinel → periclase + stishovite, or (b) spinel → periclase + MgSiO3 (corundum structure). The second reaction is considered more probable. The total increase in density caused by these phase changes between 400 and 1000 km is 0.6 to 0.7 g/cm3 (referred to zero pressure). The effect of less abundant components in the mantle such as FeO, Al2O3, CaO, and Na2O is to form solid solutions with the principal phases. This causes each of the principal phase transitions to be spread over a substantial depth range. As a result, the increase of density between 400 and 900 km is continuous. These results verify Birch's hypothesis on the constitution of the mantle and are in close agreement with the Bullen model A density distribution.

Journal ArticleDOI
TL;DR: In this article, the electric field associated with the continuing luminosity of cloud-to-ground discharges was analyzed and it was shown that negative charge from the cloud flows to ground continuously.
Abstract: About 200 excellent photographs of cloud-to-ground discharges, taken with a newly designed rotating-film camera, were obtained from very active thunderstorms in 1959 and 1960. The electric-field changes and luminosity variations of the photographed discharges were recorded simultaneously on two oscilloscopes having different time resolution. Fifty per cent of the multiple-stroke flashes, constituting about 90 per cent of cloud-to-ground flashes, are found to involve at least one stroke which is followed by very long continuing luminosity lasting for 40 to 500 msec. This continuing luminosity contains a number of relatively brighter components essentially the same as the M components which are known to follow some strokes having very short time intervals. The analysis of the electric field associated with the continuing luminosity reveals that, during the luminous period, negative charge from the cloud flows to ground continuously. The surges of current (M components) during the continuing luminosity are associated with the small rapid field changes (K changes), and the time interval between M components is statistically the same as that between the K changes generally observed during the interstroke and final period of cloud-to-ground flashes. During the period of continuing luminosity, the lightning channel maintains a level of conductivity which is high enough to support a momentary current increase without involving the leader process. After the channel loses its luminosity, it maintains a lower level of conductivity for 7 to 100 msec, and a subsequent stroke during this period can also follow the same channel. When a longer time elapses (>100 msec), a subsequent stroke, if any, takes a different channel with a new stepped leader.

Journal ArticleDOI
TL;DR: In this article, the authors extended the theory of the relationship between the tangential components of E and H for geomagnetic fluctuations over a stratified earth to take account of the distribution of the ionospheric inducing field.
Abstract: The theory of the relationship between the tangential components of E and H for geomagnetic fluctuations over a stratified earth is extended to take account of the distribution of the ionospheric inducing field. It is shown that Cagniard's simple formulas on which magnetotelluric methods are generally based need modification to take account of the dimensions of this field. This is so even when the inducing field is much more extensive than the region under consideration and when the depth of the probe is quite moderate. It is further shown that, for deep probing, magnetotelluric methods can be satisfactorily applied only if an analysis of the field over a region having dimensions comparable with those of the inducing field is first made. The relation between these methods and the earlier methods of determining the conductivity distribution from analyses of the components of the surface magnetic field is discussed. The evaluation of the amplitude and phase relations of E and H over the oceans is also discussed, and it is shown that some results obtained recently by Fonarev need extending and amending.

Journal ArticleDOI
TL;DR: In this article, a method is given for the determination of the surface deformation of the earth and the perturbation in its superficial gravity field caused by an idealized unit point-mass load placed on the surface.
Abstract: A method is given for the determination of the surface deformation of the earth and the perturbation in its superficial gravity field caused by an idealized unit point-mass load placed on the surface. By use of this Green's function the response of an accepted earth model to any superficial mass layer such as the variable ocean tide can readily be calculated. The theory is presented in this paper. Numerical results will be given in a later publication.

Journal ArticleDOI
TL;DR: In this paper, it is argued that the interplanetary gas can usefully be treated as a continuum as far as the interaction between the solar wind and the terrestrial magnestosphere is concerned.
Abstract: It is argued in this note that the interplanetary gas can usefully be treated as a continuum as far as the interaction between the solar wind and the terrestrial magnestosphere is concerned. On this basis, since the solar wind is highly supersonic near the earth, a collision free bow shock wave should be a permanent feature of interplanetary space on the sunward side of the magnetosphere. Other features of the solar wind flow pattern and the shape of the magnetosphere are also considered, and it is suggested that certain ionospheric phenomena are the direct result of linkage to the exterior surface of the magnetosphere via geomagnetic lines of force.

Journal ArticleDOI
TL;DR: In this article, it is shown that the interplanetary plasma flow measured by means of Explorer 10 is supersonic in the sense that the flow speed is greater than the Alfven speed.
Abstract: The interplanetary plasma flow measured by means of Explorer 10 is supersonic in the sense that the flow speed is greater than the Alfven speed. It is shown that this has some of the same implications as supersonic flow does in ordinary fluid flow theory, and possible consequences are discussed. The position of the shock that would develop if the interplanetary plasma were a perfect gas with a short mean free path is calculated and is shown to be well outside the orbit of Explorer 10, so that it would not have been seen. Speculations on the possible structure of the shock in collisionless plasma are given, and it is shown that this structure may account for the turbulent character of the distant magnetic field. (auth)

Journal ArticleDOI
TL;DR: In this paper, a least square curve-fitting program was developed to compute an interpretation of empirical dispersion data in terms of a layered model of the earth, which can be applied to precisely computed theoretical dispersion curves.
Abstract: A least-squares curve-fitting program in which calculations of surface wave dispersion are used has been developed in order to compute an interpretation of empirical dispersion data in terms of a layered model of the earth. Input may consist of dispersion data (phase velocity versus wave period) for both Love and Rayleigh waves in any modes of propagation. Output consists of successive approximations of the values of parameters such as layer thicknesses, shear velocities, and densities which minimize the mean square of residuals of the empirical data with respect to theoretical dispersion curves calculated from the parameters. Tests made by applying the method to precisely computed theoretical dispersion curves demonstrate the validity of the method. In these, as many as six parameters of the original theoretical models are calculated under a wide variety of conditions from the dispersion data only. In other cases, the amount of information obtainable may be greater or smaller, depending on the quality of the input data. The New York-Pennsylvania dispersion data of Oliver et al. [1961] can be successfully interpreted by using additional information from seismic refraction and studies of nearby earthquakes in the area. A solution including the important effect of the mantle low-velocity channel gives a crustal thickness of 38.6 km, a crustal shear velocity of 3.64 km/sec, a shear velocity of 4.685 km/sec below the M discontinuity, and a ratio of 2.86/3.30 between crustal and subcrustal density values. The density measurement is a new result. The shear velocity structure derived here is consistent with results obtained by Katz from seismic refraction profiles in the same area. Additional data are needed in order to derive more detailed information on crustal structure.

Journal ArticleDOI
TL;DR: In this article, structural and physiographic features of the 1200 km-long Philippine fault zone are fully as spectacular as those of the better-known San Andreas and Alpine faults, and current activity is indicated by many localities in which scarps cut Recent gravels.
Abstract: Conflicting views of circum-Pacific tectonics have focused on the Philippines-Taiwan region, where there has been neither convincing documentation nor general agreement on the importance of transcurrent (strike-slip) faulting or the possible sense of regional horizontal displacement. Structural and physiographic features of the 1200-km-long Philippine fault zone are fully as spectacular as those of the better-known San Andreas and Alpine faults, and current activity is indicated by many localities in which scarps cut Recent gravels. Predominance of horizontal over vertical displacements is indicated by linearity of the fault trace, failure of one side to be consistently higher than the other, disregard for gross physiography, and scissoring of individual scarps within the zone. Consistent stream offsets on Luzon, Masbate, and Leyte demonstrate unequivocally that the sense of Recent displacement has been uniformly sinistral (left-handed). The Philippine fault has no obvious geologic relationship to active volcanoes, but the parallelism and proximity of the fault to the Mindanao trench suggest a close causal relationship. The remarkable Longitudinal Valley of eastern Taiwan represents another great transcurrent fault parallel to the western Pacific rim, and ground displacements during historic earthquakes indicate a sinistral sense of displacement here as well as in the adjacent Philippines. This study does not support the hypothesis of counterclockwise rotation of the Pacific basin, but more important is the further documentation of the predominance of transcurrent faulting in active circum-Pacific orogenic areas. These results reinforce earlier field studies in Alaska, California, Chile, and New Zealand, as well as emphasizing the geological reasonability of the results of seismic fault-plane solutions indicating the world-wide predominance of transcurrent movements.

Journal ArticleDOI
TL;DR: The boundary of the solar corpuscular stream produced by interaction with the magnetic dipole field of the earth is shown in this paper, where the magnetic field is assumed to be neutral.
Abstract: Form of the boundary of the solar corpuscular stream produced by interaction with the magnetic dipole field of the earth

Journal ArticleDOI
TL;DR: In this paper, Malan and Pierce measured and calculated the charge brought to earth by individual strokes and continuing currents from lightning flashes in New Mexico thunderstorms and concluded that earlier measurements of J changes for distances greater than 50 km must be interpreted as having been produced by the continuous flow of negative charge to earth instead of by the upward movement of positive charge contained within the cloud.
Abstract: Results of measurements and calculations of the charge brought to earth by individual strokes and continuing currents from lightning flashes in New Mexico thunderstorms are presented Hybrid flashes, which contain at least one long-continuing current interval, lower approximately twice as much charge as do the discrete flashes The average value of negative charge lowered to earth in hybrid flashes is 34 coulombs compared with 19 coulombs for the discrete flashes, a difference accounted for by the presence of the long-continuing (>40 msec) current intervals of average duration 150 msec, during which time an average charge of 12 coulombs is lowered to earth The continuing currents vary over a relatively narrow range from a minimum of 38 amp to a maximum of 130 amp Some aspects of the J-change measurements of Malan and of Pierce are reexamined in the light of the magnitude and frequent occurrence of the continuing currents It is concluded that earlier measurements of J changes for distances greater than 50 km must be interpreted as having been produced by the continuous flow of negative charge to earth instead of by the upward movement of positive charge contained within the cloud

Journal ArticleDOI
TL;DR: In this article, a principle of particle segregation by freezing is presented, which is demonstrated experimentally by means of a transparent freezing cabinet in which a sample of distilled water freezes from the bottom upward.
Abstract: A principle of particle segregation by freezing is presented. It is demonstrated experimentally by means of a transparent freezing cabinet in which a sample of distilled water freezes from the bottom upward. In this way the freezing front line travels vertically and the particles are carried against gravity. By use of the same material with different shapes (glass beads and broken quartz or glass) it is demonstrated that an important factor in particle migration is the shape of the particle or its contact area with the interface. Other materials with different shapes and sizes were tested. The other important factors are particle size and rate of freezing. Fine particles migrate under a wide range of rates of freezing; coarser particles migrate at slower and narrower ranges of rates of freezing. It is suggested that, for determining frost behavior of soils in permafrost regions, freezing from the bottom upward is a more reliable test than freezing from the top down. Freezing from the bottom more closely approximates freezing of the active layer above permafrost; also friction with the cylinder testing wall is eliminated. The implication of this principle in engineering and studies of soil genesis in cold regions is emphasized.

Journal ArticleDOI
TL;DR: In this paper, the authors used homogeneous wave guide theory to derive dispersion curves, vertical pressure distributions, and synthetic barograms for atmospheric waves, and found that the major features on barograms are due to dispersion; superposition of several modes is needed to explain observed features.
Abstract: Homogeneous wave guide theory is used to derive dispersion curves, vertical pressure distributions, and synthetic barograms for atmospheric waves. A complicated mode structure is found involving both gravity and acoustic waves. Various models of the atmosphere are studied to explore seasonal and geographic effects on pulse propagation. The influence of different zones in the atmosphere on the character of the barograms is studied. It is found that the first arriving waves are controlled by the properties of the lower atmospheric channel. Comparison of theoretical results and experimental data from large thermonuclear explosions is made in the time and frequency domains, and the following conclusions are reached: (1) The major features on barograms are due to dispersion; (2) superposition of several modes is needed to explain observed features; (3) scatter of data outside the range permitted by extreme atmospheric models shows the influence of winds for A1; wind effects and higher modes are less important for A2 waves. A discussion is included on atmospheric terminations and how these affect dispersion curves.

Journal ArticleDOI
TL;DR: In this paper, a model is formulated in which the proportion and age of reworked material that is incorporated into new sialic basement are related to the Sr87/Sr86 development in the various materials involved.
Abstract: Rubidium and strontium are used as tracers in the history of differentiation of the continental sial, and for this purpose it is assumed that the Rb/Sr ratio follows the aggregate enrichment of sialic components sufficiently well to represent an approximately linear measure of the entire process. Measurements of the Sr87/Sr86 ratios in basalts and other igneous rocks of subsialic origin suggest that the source regions of sial have had a Sr87/Sr86 ratio in the range 0.705 to 0.710 in different areas and at different times in the span of geologic history. Measurements of the Rb/Sr ratio in sialic rocks of the continental crystalline basement have indicated that the weighted average value for this ratio is in the vicinity of 0.25. This means that the Sr87/Sr86 ratio in average sialic rocks of the continental basement would increase at a faster rate than that in the subsialic source regions, by an amount equal to approximately 0.010 per billion years. This is more than five times the standard deviation precision error in measurement. A comparison of the ratio Sr87/Sr86 with the geologic age of the rock, in samples of typical sialic basement rocks leads to the conclusion that there has been a continuous generation of primary sial from subsialic source regions that has caused the continental areas to grow roughly in proportion to the extent of the geological age provinces. In North America this areal growth is estimated to be at the average rate of about 7000 km2/m.y., and it seems to have been operative over most of geologic time. A model is formulated in which the proportion and age of reworked material that is incorporated into new sialic basement are related to the Sr87/Sr86 development in the various materials involved. The model is generalized with all the parameters left open. An example set of values for the various parameters is tested on the model to indicate where there is need for more definitive data. This example set is derived from data available at present which, although very limited, indicate clearly that if the reworked material is young enough it can constitute a major proportion of a new sialic basement area, but if it is ancient (1 to 2 b.y. in primary age prior to incorporation) it could not be present in more than a minor proportion of the typical new basement.

Journal ArticleDOI
TL;DR: There are limits, therefore, upon increasing the information content of a mean by utilizing the information contained in a related series, as cross-correlation tends to decrease the effective length of series for computing regional means.
Abstract: The amount of information given by a statistical estimate is defined as the reciprocal of the variance of the estimate. In this study, a random series is adopted as the standard of information content. The relative information content of the mean for various types of hydrologic series is defined as the ratio of the variance of the mean for a random series to the variance of the mean for given types of series. Beyond the well-known fact that the sequential correlation in hydrologic series reduces the effective length of the series, the sequential correlation tends to impair the effectiveness of cross-correlations between series. There are limits, therefore, upon increasing the information content of a mean by utilizing the information contained in a related series. Moreover, cross-correlation tends to decrease the effective length of series for computing regional means.

Journal ArticleDOI
TL;DR: In this paper, the authors compared the meridional transport of heat by ocean currents in the northern hemisphere, as calculated from heat-balance maps of the oceans compiled by Budyko and Albrecht, compared with a similar calculation by Sverdrup.
Abstract: The meridional transport of heat by ocean currents in the northern hemisphere, as calculated from heat-balance maps of the oceans compiled by Budyko and Albrecht, is compared with a similar calculation by Sverdrup. The transports are in best agreement in the northern part of the North Atlantic. Discrepancies occur in the Pacific and in the equatorial Atlantic. To calculate meridional heat transport directly, a method is formulated for combining hydrographic station data and climatological estimates of surface wind stress. The method is applied to hydrographic sections made by individual expeditions during the IGY and NORPAC programs. Transient changes in the density field introduce a large sampling error, but these measurements have the advantage of providing some physical insight into the mechanism of heat transport. The principal conclusions of the study are: (a) Circulations in the vertical plane account for at least half as much meridional heat transport as the large-scale horizontal circulation of ocean basins; (b) the NORPAC Pacific section made in August 1955 at 35°N indicates a transport of heat southward, toward the equator, comparable in magnitude to northward heat transport measured in the North Atlantic.

Journal ArticleDOI
TL;DR: In this paper, the authors reported radioactive disequilibrium in nature between U234 and its parent U238 and used this anomaly as a geochemical tool in the study of the behavior of U in rocks, soils, and natural waters.
Abstract: Recently, several workers, reported radioactive disequilibrium in nature between U234 and its parent U238. This anomaly may be used as a geochemical tool in the study of the behavior of U in rocks, soils, and natural waters. Samples of unraninite and Mississippian limestone in which U234 was expected to be in equilibrium with U238 were analyzed. Preliminary values for the oceans are given. Several samples from Eniwetok and Lake Bonneville were analyzed.

Journal ArticleDOI
TL;DR: In this article, the amount of dispersion produced by the paleosecular variation in the magnetization of a rock formation against the background of noise due to experimental errors, partial remagnetization, subsequent tectonic movement, etc.
Abstract: In studies of the paleosecular variation the situation often arises that, although a number of spot readings of the paleogeomagnetic field have been deduced from the fossil magnetization of a rock formation, their stratigraphic sequence is unknown. Hence, in this paper, methods are discussed of deducing the amount of dispersion produced by the paleosecular variation in the magnetization of a rock formation against the background of noise due to experimental errors, partial remagnetization, subsequent tectonic movement, etc. The secular variation recorded at observatories and field stations during the past few centuries does not cover the full range of dispersion of the geomagnetic field in time, and models are considered by means of which this may be estimated. Angular dispersion factors are defined and have been calculated for three models and found to be of the same magnitude as those calculated from various rock formations. Other calculations for these models predict that the secular variation dispersion depends on latitude, and data from a number of igneous rock formations appear to confirm this prediction. It is not possible, however, to calculate the dispersion due to the paleosecular variation from the large body of paleomagnetic data tabulated by various authors, since these data have been computed in different ways.

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TL;DR: In this article, a free piston gage capable of measuring pressures to 60 kb has been constructed, which is the basic element of the gage is a supported carbide vessel entered by a rotating piston.
Abstract: A free piston gage capable of measuring pressures to 60 kb has been constructed. The basic element of the gage is a supported carbide vessel entered by a rotating piston. With this apparatus the pressures of various transitions have been determined with fair precision. We find the following pressures: Teflon, 5.43 kb; AgNO3 I-AgNO3 II, 9.78 kb; KI I-KI II, 17.48 kb; KBr I-KBr II, 17.88 kb; KCl I-KC1 II, 19.28 kb; KCN I-KCN II, 19.72 kb; Ice VI-Ice VII, 21.42 kb; AgNO3 II-AgNO3 III, 21.2 kb; Cs I-Cs II, 22.6 kb; Bi I-Bi II, 25.38 kb; Bi II-Bi III, 26.92 kb; Tl II-Tl III, 36.69 kb; Te I-Te II, 40.12 kb; Cs II-Cs III, 41.7 kb; Ba II-Ba III, 59.6 kb. These results are in close agreement with earlier measurements of discontinuities in volume made by Bridgman.