bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinematics of wrench and divergent‐wrench deformation along a central part of the Border Ranges Fault System, Northern Chugach Mountains, Alaska
Authors: Little Timothy A.
Published: February 2008

The Border Ranges fault system (BRFS) bounds the inboard edge of the subduction‐accretion complex of southern Alaska. In Eocene time a central segment of this fault system was reactivated as a zone of dextral wrench‐ and oblique‐slip faulting having a cumulative strike‐slip offset of at least several tens of kilometers, but probably less than 100 km. Early wrench folds are upright, trend at less than 45° to the strike of adjacent faults and developed with fold axes oriented subparallel to the axis of maximum incremental stretch λ1. These en echelon folds rotated and tightened with progressive deformation and then were overprinted by younger wrench folds that trend at about 60° to adjacent throughgoing faults. The latter folds are interpreted as forming during a late increment of distributed wrench deformation within the BRFS that included a component of extension (divergence) orthogonal to the mean strike of the fault system. A sharp releasing bend in exposures of a strike‐slip fault originally at >4 km depth today coincides with a narrow pull‐apart graben bounded by oblique‐normal faults that dip toward the basin. Widening of this pull‐apart graben by brittle faulting and dike intrusion accommodated less than 2 km of strike‐slip and was a late‐stage phenomenon, possibly occurring at supracrustal levels. Prior to formation of this graben during a period of predominantly ductile deformation at deeper structural levels, wrench‐folded rocks on one side of the nonplanar fault were translated around the releasing bend without significant faulting or loss of coherence. Kinematically, the earlier deformation was accomplished by fault‐bend folding and rotation of a relatively deformable block as it passed through a system of upright megakinks. Such a ductile mechanism of fault block translation around a strike‐slip bend may be typical of intermediate levels of the crust beneath pull‐apart grabens and may be transitional downward into heterogeneous laminar flow occuring along curved segments of ductile shear zones. Some degree of fault‐bend folding of strike‐slip fault blocks around releasing bends may be one reason why the amount of extension measured across natural pull‐apart basins is commonly observed to be less than the amount of strike‐slip along their master faults.
Structure and tectonics of the Yucatan Basin, caribbean Sea, as determined from seismic reflection studies
Authors: Rosencrantz Eric
Published: February 2008

The Yucatan Basin preserves a record of the Late Cretaceous to Paleogene Caribbean‐North American convergent history that is largely unaffected by Neogene strike‐slip tectonics of the current plate boundary. An examination of seismic basement within the Yucatan Basin, based upon available seismic reflection data including extensive multichannel data, shows that the basement comprises nine domains distinguished on the basis of internal reflection character and surface topography. These domains encompass three distinct crustal types or blocks. The first underlies the western flank of the basin and represents the offshore continuation of the adjacent Yucatan platform. The second includes the topographically heterogeneous domains of the eastern two‐thirds of the basin, and is dominated by a subsided volcanic rise or arc (Cayman rise) resting upon probable oceanic crust of pre‐Tertiary age. The eastern edge of the rise and adjacent basins dips northeast beneath the Cuban margin along a sediment filled trench. The third type of crust occupies a rectangular deep within the western third of the basin. Available evidence indicates that this crust is oceanic in character, and represents a large, mature pull‐apart basin set within a wide paleo‐transform zone between the western platform and eastern oceanic basin. This zone defines the northwestern portion of the Caribbean‐North American convergent plate boundary. Paleocene to Middle Eocene transform motion was left‐lateral along north‐south to NNE‐SSW trends, with a displacement of about 350 km. A long Middle Eocene transcurrent fault of about 50 km left‐lateral displacement cuts the basin diagonally from SW to NE and continues onland in Cuba as La Trocha fault. This reconstruction is consistent with known Eocene regional tectonics, but the timing of regional events raises questions about present interpretations of plate geometry in the northwestern Caribbean.
Geologic evidence for the plate‐driving mechanism: The continental undertow hypothesis and the Australian‐Antarctic discordance
Authors: Alvarez Walter
Published: February 2008

Investigations of the pattern of flow in the mantle have been carried out almost exclusively by theoretical geophysicists, mainly fluid dynamicists, because mantle flow has been considered too deep and too disconnected to leave direct traces in surface tectonic geology. This geophysical approach has not yet provided a detailed understanding of mantle flow. The assumption of invisibility of mantle flow from the surface should be reassessed. The tectonic history of gaps in the circum‐Pacific ring of continents (Caribbean, Scotia Sea, Australian‐Antarctic Discordance) suggests that upper mantle return flow is escaping from the Pacific hemisphere as the Pacific Ocean contracts and is avoiding the regions beneath continents. Major continental masses may thus have the deep roots suggested by some seismologists. If these roots are coupled to the lower mantle, plates that include continents may be driven by “continental undertow.” In this case, continental motions may tell us the pattern of lower mantle flow, and the resulting four‐celled lower mantle picture is remarkably simple. A key area for testing the continental undertow hypothesis is the Australian‐Antarctic Discordance, a low saddle on the spreading ridge between these two continents. In the continental undertow view, upper mantle flow escaping the Pacific is met in the discordance by upper mantle flow originating at the Java‐Sumatra trench, with the bathymetric low representing the sink toward which this converging flow is moving. Two new lines of evidence support this interpretation: (1) Isotope geochemistry of ridge basalts from the discordance shows that mantle sources with distinctive Pacific Ocean and Indian Ocean characters meet precisely at the discordance. (2) Seismic tomography reveals cool upper mantle under the discordance, which argues for feeding of this ridge segment laterally, rather than from beneath. Hot spot tracks in and just east of Australia appear to argue against the continental undertow hypothesis but do not allow an unambiguous test of the continental undertow hypothesis. Mantle flow patterns may in fact be partly visible from the surface, and careful evaluation of key regions by tectonic geologists may provide a fruitful approach to understanding mantle dynamics.
The use of a forward kinematic model in the construction of balanced cross sections
Authors: Endignoux Lionel , Mugnier Jean‐Louis
Published: February 2008

Nowadays, cross section balancing is a popular technique. However, there is sometimes a lack of data at depth so that the problem is not clearly expressed in terms of the kinematics of deformation. In this paper a forward modeling program of thrusting is presented, which when used with a trial and error procedure allows the simulation of intermediate and final state geometries of a thrust belt. Together with the classic assumptions used in cross section balancing, severals rules for fault bend folding have been selected for use in this model. The forward modeling illustrates three important characteristics of balanced cross sections: (1) the critical importance of stratigraphic thickness and displacement at the trailing boundary, (2) the redundant character of angular surface data, (3) the generally unconstrained character of the problem. Advantages derived from using a forward modeling approach are: (1) to examine the validity of several different structural interpretations in which the input parameters may be varied, (2) to simulate both final and intermediate stages, and (3) to generate the large displacement of a mesh necessary for the application of physical models. In the last part of the paper, geological structures of the Appalachian Mountains, Jura, and Barbados accretionary prism are modeled.
Beobachtungen über die Eigenelectricität der atmosphärischen Niederschläge
Authors: Elster Von J. , Geitel H.
Published: February 2008

Die electrischen Vorgänge in der Atmosphäre lassen sich zweckmässig unter drei Gruppen verteilen, deren erste diejenigen in sich schliesst, die auf der Existenz eines periodisch veränderlichen und im allgemeinen auch von Ort zu Ort verschiedenen electrischen Feldes in dem von eigentlichen Niederschlägen freien Luftraume beruhen, deren zweite die Störungen umfasst, die sich zugleich mit dem Auftreten von Niederschlägen innerhalb jenes Feldes einzustellen pflegen, während die dritte die Polarlichter und die mit ihnen verbundenen electrischen Wirkungen in sich begreift.

Es ist möglich, dass die in diesen Gruppen zusammengefassten Vorgänge, obgleich sie alle das electrische Feld an der Erdoberfläche beeinflussen können, im wesentlichen von einander unabhängig sind und innerlich nicht enger zusammenhängen als etwa um ein Beispiel aus dem thermischen Verhalten der Atmosphäre zu wählen, die durch Insolation des Erdbodens herbeigeführte Temperaturerhöhung der Luft mit der in absteigenden Strömungen auftretenden Erwärmung, wie sie in dem Föhnphänomen beobachtet wird.
Results of magnetic and electric observations made during the solar eclipse of June 8, 1918: Concluded
Authors: Bauer L. A. , Fisk H. W. , Mauchly S. J.
Published: February 2008

Part III.—Atmospheric‐electric observations: Concluded

Atmospheric‐electric observations at Lakin, Kansas: Concluded
Results and analysis of magnetic observations during the solar eclipse of May 29, 1919.—Summary I
Authors: Bauer Louis A.
Published: February 2008

INTRODUCTION.

1. The total solar eclipse of June 8, 1918, was the recurrence of the one of May 28, 1900, for which the writer planned and directed the first systematic observations arranged to detect a possible appreciable magnetic effect connected directly with the eclipse of the Sun. For both eclipses, 1900 and 1918, the results were affirmative, as well as instructive. The total eclipse of the Sun on May 29, 1919, was the recurrence of the one of May 18, 1901, the belt of totality of which began in the Indian Ocean, about where the totality‐belt for May 29, 1919, ended, and continued across Sumatra to New Guinea. The international magnetic observations for May 18, 1901, made in accordance with the writer's appeal and directions, again led to positive results and gave additional information.
Results of Earth‐resistivity surveys near Watheroo, Western Australia, and at Ebro, Spain
Authors: Rooney W. J. , Gish O. H.
Published: February 2008

In the study of terrestrial electricity and allied phenomena a knowledge of the specific resistance of the Earth's crust is essential. And while the resistivity of its constituent elements is generally well known for laboratory conditions, but few data are available on the resistivity of the crust itself and its distribution laterally and with depth. As a first step in acquiring these data, the Department of Terrestrial Magnetism of the Carnegie Institution of Washington has undertaken a series of resistivity surveys in regions where records of earth‐current potential gradient are being obtained. By combining the resistivity results with the records of potential gradient, the actual current densities may be compared.
Earth‐resistivity measurements in the copper country, Michigan
Authors: Rooney W. J.
Published: February 2008

During the summer of 1927 the Department of Terrestrial Magnetism of the Carnegie Institution of Washington and the Michigan College of Mines and Technology engaged in conducting jointly a series of earth‐resistivity measurements in the Copper Country of northern Michigan, where the geological structure is well known, to determine the value of measurements of resistivity and its variations as indications of the geological structure below the surface. The work done may be roughly divided in two parts: First, measurement and study of the variations in resistivity with depth, or with volume, to establish such general relations as exist between the two; and, second, the determination of the resistivity of specific rock‐flows, in order that more fundamental data be made available as an aid to the interpretation of the results of the former type of measurement.

The results of the first part of the investigation bear out the evidence from previous work that resistivity‐determinations may be used to advantage in determining the location of certain underground discontinuities. The data obtained in the second part on the resistivity of specific rocks are also in line with previous results. The resistivity of porous, sedimentary rocks was usually under 20,000 ohms per centimeter cube, while traps and associated rocks of volcanic origin were found to have resistivities from five to twenty times as great.
Giant micropulsations at Abisko
Authors: Rolf Bruno
Published: February 2008

At the Geophysical Observatory of Abisko, Swedish Lapland, a set of Toepfer variometers has been in operation since midsummer 1921, with a break of one month only in October to November 1927, when more rigid mountings were made. The time‐scale has been 20 mm per hour and sensitivities of 5γ in eastward, 10γ in northward, and 8γ in vertical component per mm most of the time

The portions of records reproduced in Figure 1 were obtained on September 10 and 12, 1930, and illustrate a special kind of rare perturbation, which occurs distinctly only three or four times a year at Abisko. Its characteristic feature is a regularly emerging and vanishing sinusoid with period of order of one minute. With more sensitive instruments, somewhat regular pulsations are not uncommon, and their existence is well known to scientists even at lower latitudes. My first acquaintance with similar phenomena dates back to August 1914, when in charge of the temporary magnetic station erected in connection with the solar eclipse at Strömsund, Central Sweden. Professor V. Carlheim‐Gyllensköld at once directed my attention to the explanation of Eschenhagen's “Elementarwellen” given by Professor C. Störmer2 in 1906. The sensitivity in the Strömsund records for all elements was about 1.67 per mm, and in a fortnight similar micropulsations were conspicuous several times with a range of about 1γ. The pulsations of September 12, 1930, at Abisko, however, had ranges of 14γ in the northward component, 34γ in the eastward, and 23γ in the vertical component. True giant amongst dwarfs! There were about 50 full swings with a mean period of 111 seconds, and the phenomenon lasted for 1 hour and 27 minutes.
On pulsations of terrestrial magnetism and their possible explanation by periodic orbits of corpuscular rays
Authors: Störmer Carl
Published: February 2008

(1) In a paper published in 19061 I suggested as a possible explanation of the terrestrial‐magnetic disturbance called “Eschenhagens Elementarwellen” the action of clouds of electric corpuscles moving along periodic orbits in space far away from the Earth.

A rough calculation of the periods from certain types of calculated orbits gave periods of the same order as those observed, and the fact that these waves are a phenomenon which occurs simultaneously all over the Earth2 seems to indicate that their origin must lie far out in space and must be of a cosmical nature.
Magnetic work of the Dominion Observatory, Ottawa, Canada, 1907–1932
Authors: French C. A.
Published: February 2008

The decision to make the September issue of the JOURNAL a memorial number in honor of Dr. Bauer, the greater part of whose life was devoted to the study of problems relating to the Earth's magnetism, is to be commended. On account of his great interest in magnetic work in Canada as well as that carried on by organizations generally, it seems fitting that a review be given of the work of the Dominion Observatory, touching upon some of the problems encountered in an endeavor to make a systematic magnetic survey of the Dominion of Canada. It is, moreover, considered as an opportunity of paying some slight tribute to the memory of Dr. Bauer, who, in Canada, was so well known as a scientist and highly esteemed as a man.

In tracing the history of terrestrial magnetism, or for that matter any other line of endeavor, it is noted that with every advance there is invariably the personal as well as the historical aspect. Thus it is that our knowledge of the declination of the compass is credited to Columbus; with the announcement in 1600 that the Earth itself is a great magnet is associated the name of Gilbert; Halley, who realized the practical importance of the science, was responsible for the first chart of magnetic declination which appeared in 1701; and with the impetus given to the study of terrestrial magnetism during the first half of the nineteenth century is associated the name of Gauss, especially noted for his theoretical discussions in which he was ably assisted by Humboldt, Sabine, and other eminent investigators whose record of achievement was a fine example of cooperative effort.
Oscillations and vibrations in magnetic records at high‐latitude stations
Authors: Harang Leiv
Published: February 2008

It is a well‐known fact that more or less pronounced perturbations or oscillations occur on the records from all observatories, if the variometers used are sufficiently sensitive. Eschenhagen1 who first investigated these small perturbations, used an H‐variometer with a sensitivity of 0.3 γ/mm and speed of registration of 4mm/min. The registrations showed that in a number of cases these smallest perturbations consisted of fairly regular sinusoidal oscillations. The period of the oscillations varied, but it was most frequently 30 to 40 seconds with an amplitude of 1γ to 2γ. Eschenhagen also showed that by increasing the sensitivity of the variometers further details were not obtained on the curves. He called these smallest perturbations elementary waves as they, in his opinion, represented the limit in the analysis of the perturbations of the magnetic field. These elementary waves of Eschenhagen are especially interesting since among the various forms of magnetic perturbations they exhibit a simple geometric one.
Solar eruptions and their ionospheric effects—A classical observation and its new interpretation
Authors: Bartels J.
Published: February 2008

The important discovery that bright eruptions in the solar chromosphere cause simultaneous radio fade‐outs and distinct terrestrial magnetic effects has been announced and discussed in the last issues of this JOURNAL. J. A. Fleming, giving an outline of the bearing of this new evidence on theories of the ionosphere and terrestrial‐magnetic variations, mentions that Carrington and Young nearly 80 years ago interpreted certain observations as indicating the simultaneity of solar eruptions and magnetic disturbances, but that this opinion was abandoned by other investigators because they looked for it in vain in the great magnetic storms. If the radio fade‐outs had not given such strong evidence of ionospheric disturbances simultaneous with solar eruption, it is not impossible that the comparatively small, though distinct terrestrial‐magnetic effects would still have escaped detection.

This discovery has been made possible by the increase in the program of spectroscopic, ionospheric, and terrestrial‐magnetic observations, and by the comparative frequency with which intense fade‐outs occur (21 fade‐outs in the year 1936, of which at least 13 were accompanied by visible solar eruptions). As the observational material for great magnetic disturbances increases much more slowly, with only a few cases during each sunspot‐maximum, we have still to rely on the numerous discussions of the relationship to sunspots, which may be interpreted 2 evidence for solar corpuscles, traveling about a day from the Sun 1 the Earth. Because of the rarity mentioned, and not only for historic reasons, it may be of interest to recall here the original records of the classical case which started the controversy.
Electromagnetic method for testing rock‐samples
Authors: McNish A. G.
Published: February 2008

Intensive study of the remanent magnetization of rocks should reveal information of profound importance to investigators in terrestrial magnetism and geology. If magnetic precipitates are permitted to settle from a solution the particles align themselves so that the sediment is magnetized in the direction of the prevailing magnetic field. Similarly, a magnetic substance when cooling, if its original temperature is above the Curie point for that substance, becomes magnetized in the direction of the prevailing field. For these reasons both sedimentary and igneous rocks may be expected to assume a magnetic condition corresponding to the Earth's magnetic field prevailing at the time and place of their formation.
Magnetic Observatory, Capetown July to December, 1938
Authors: Ogg A.
Published: February 2008

July 1—Bays developed in all elements at 22h 37m GMT, July 1. The following changes occurred: D, +8′ in twenty minutes and −8′ in sixty‐five minutes; H, +26 gammas in fifteen minutes and −8 gammas in sixty minutes; Z, +56 gammas in fifteen minutes and −36 gammas in sixty minutes.

July 13–14—A sudden commencement was recorded at 20h 24m GMT, July 13. H increased 16 gammas in five minutes. The storm lasted for eight hours during which the ranges were: H, 60 gammas; Z, 50 gammas.
Some characteristics of auroras in New Zealand
Authors: Geddes M.
Published: February 2008

Work on the aurora in New Zealand has been carried out intensively since the beginning of 1933. As this period completely covers the rise from minimum to maximum activity a survey of the general characteristics of the auroras observed may be profitable. The study consisted, until 1935, in the collection of data for statistical use, but, since then, with the assistance of Professor C. Störmer, photographic work has been undertaken, and, since the end of 1936, two cameras have been in constant use for height determinations.
Geomagnetic tides in horizontal intensity at Huancayo, Part II
Authors: Bartels J. , Johnston H. F.
Published: February 2008

After the completion of Part I and of the summary [reference 4 in Part I], a new viewpoint was found which seemed likely to lead to better methods than those used hitherto in the computation of the lunar diurnal variation L, for the main term L(M2) arising from the partial tide M2 and also the subsidiary terms depending on lunar distance. This led to a “principle of efficient sampling in geophysical statistics” (21), a general expression for ideas underlying previous work. This principle when applied to present methods of computing L, reveals the main reason for the rather unsatisfactory results of former computations on L. These results showed irregularities indicating the presence of large residuals due to non‐lunar influences, both “regular” (such as that due to the average value of the solar daily variations S)—believed to be eliminated—and “irregular” (such as that due to disturbance or the variability of S)—believed to be sufficiently “overwhelmed” by combining a great number of observations.
The Geographic Incidence of Aurora and Magnetic Disturbance, Southern Hemisphere
Authors: Vestine E. H. , Snyder E. J.
Published: February 2008

In the present paper average features of geomagnetic disturbance and aurora in south polar regions are compared with those derived on the basis of more extensive data for high northern latitudes. The seasonal and yearly average of the disturbance daily variation (SD) is obtained for various stations in Antarctic regions and its variation in amplitude with latitude compared with that for the Northern Hemisphere. These data are used to estimate the position of the southern zone of maximum auroral frequency and this result compared with available yearly frequencies of aurora. A particular aim of the investigation is the clear indication of present deficiencies in observational data, both magnetic and auroral, and of the regions most in need of additional observations.
Noise observed during radio fade‐out, August 17, 1945
Authors: Watts J. M.
Published: February 2008

Observations were made on B.A.D. Type‐249 ionospheric recorder, two signal‐intensity recorders, and by monitoring on the HRO receivers of the signal‐intensity recording equipment during a sudden fade‐out on August 17, 1945, at the Maui (Hawaii) Ionospheric Station.

The fade‐out commenced at 20h 20m GCT (10h 20m, 150° west meridian time) when the signal strength of KQF, 13.495 Mc/sec (Oahu) and KGEX, 15.13 Mc/sec (San Francisco) as received at Maui dropped abruptly to threshold value. The fade‐out was also observed at Washington from 20h 20m to 21h 45m GCT on circuits to Ohio, England, Mexico, Brazil, and Chile, as well as at vertical incidence. At the Christmas Island Ionospheric Station total absorption began abruptly with the vertical‐incidence observation at 20h 30m GCT and continued for 20 minutes. Partial fadeout was still evident through the record taken at 21h 30m GCT. The fadeout also is visible on vertical‐incident observations at College, Alaska, beginning at 20h 22m GCT.
Currents of atmospheric electricity
Authors: Chalmers J. Alan , Little E. W. R.
Published: February 2008

Summary—An account is given of recordings of vertical electric currents in the atmosphere from November, 1938, to August, 1939. General results are given and some special phenomena analysed in detail.
Land use, snow, and streamflow regimen in central New York
Authors: Satterlund Donald R. , Eschner Arthur R.
Published: February 2008

Over a 23‐year period the winter‐spring high runoff regimen from a reforested watershed in central New York was compared with that of a nearby agricultural watershed. Techniques for analyzing regimen over a large range of flow and time were developed from Court's half‐flow date and duration concepts and selected daily flow data. The techniques revealed that runoff during snowmelt periods is gradually concentrated in a shorter time following reforestation of open lands. There is also a gradual desynchronization with runoff from the agricultural watershed, so that concentrated snowmelt runoff comes later in the season in the years following reforestation. The desynchronization is apparent over the entire range of flow and time studied, from mean daily flows of 7 cubic feet per second per square mile to half of the annual flow, which appears over a period as long as several months. The techniques used are evaluated in terms of their applicability as measures of streamflow regimen and their validity in detecting changes in regimen resulting from changes in land use.
Reynolds Creek in southwest Idaho: An outdoor hydrologic laboratory
Authors: Robins J. S. , Kelly L. L. , Hamon W. R.
Published: February 2008

The 93‐square‐mile experimental watershed in Reynolds Creek is aimed toward the solution of water yield, flood flow, and sedimentation problems of the plateau and foothills grazing areas of the northwest. This watershed was selected in 1960 specifically to permit experimental isolation of the several factors affecting the well‐known water balance equation. Basic networks for measurements and compilation of inventories of soils, vegetation, surface geology, and topography have been substantially completed. Detailed studies on small, simple watersheds with identifiable characteristics will provide basic understanding of hydrologic processes, which can be tested on the larger, complex subwatersheds of the Reynolds Creek basin.
Estimates of extreme values by different distribution functions
Authors: Majumdar K. C. , Sawhney R. P.
Published: February 2008

A comparative study of the estimates of extreme values as would be given by log‐normal distribution, extreme‐value distribution, and Foster's type 3 distribution has been made under the assumption that the population distribution is either log‐normal or of the extreme‐value type. The results of the studies are based on theoretical expressions and on a sample of 1000 observations from an extreme‐value population. Factors of converting estimates by one method to estimates by other methods have been derived. It is found that the extreme‐value distribution gives quite good estimates for return periods up to 1000 years when the coefficient of variation is less than 0.5, whereas Foster's type 3 distribution gives estimates within 5% of those given by extreme value and the log‐normal distribution under any assumption of population distribution.
Areal variability of low flows in a basin of diverse geologic units
Authors: Schneider William J.
Published: February 2008

Large‐scale areal variations in low‐flow characteristics of streamflow are caused primarily by differences in geology in the 576‐square‐mile Swatara Creek basin just east of Harrisburg, Pennsylvania. Although the low‐flow index (the average annual minimum daily flow) of small streams in the basin ranges from 0 to slightly more than 1.0 cubic foot per second per square mile (csm), the flows within each geologic zone show marked similarity, except where affected by mining, diversion, or other activity of man. These natural average minimum flows are lowest in the area underlain by the Martinsburg Shale and range from 0.01 to 0.10 csm. Moderate average minimum flows of 0.1 to 0.2 csm occur in the areas underlain by sandstone, conglomerate, and shale in the northern mountainous part of the basin; greater average minimum flows of 0.3 to 0.4 csm occur in the zone in the southern part of the basin underlain by the Gettysburg Shale, which consists mostly of coarse‐grained sandstone. The variability in the low‐flow indices of streams is greatest in the area underlain by various limestones and dolomites, ranging from zero to over 1.0 csm. However, even within this zone of limestones and dolomites there is reasonable consistency to the low flows within each of the several formations.
Flow in heterogeneous porous mediums: 1. Darcian‐type description of two‐phase systems
Authors: Nelson R. William
Published: February 2008

Theoretical work leading to the description of fluid flow in a heterogeneous porous medium has developed slowly and somewhat sporadically, even though the areas of engineering applications predominantly involve flow in a nonhomogeneous medium. In providing a theoretically consistent basis for analysis, the special characteristics of macroscopically heterogeneous materials are discussed to provide accurate definitions. The definitions establish the functional dependence and make mathematical representation possible. The special implications of heterogeneity in Darcian‐type dynamic relationships for each of the fluid phases are considered, and the rotational velocity field resulting from nonhomogeneity is shown as a contrast to the classical irrotational case for flow in a homogeneous medium. The velocity field is also shown to be the classical complex lamellar type; hence considerable insight into the flow fields in heterogeneous mediums is immediately available. The end result of the discussion and derivation is a set of rather general Eulerian equations describing two‐phase flow in a macroscopically heterogeneous medium. These equations and their reduced forms include descriptions of some forty different flow systems. Such a variety of flow conditions is categorized through the use of a special tabular scheme, which makes it possible to write the appropriate equations efficiently. (Key words: Flow; heterogeneous porous mediums; equations)
Theory and flow nets for rain and Artesian water seeping into soil drains
Authors: Hinesly T. D. , Kirkham Don
Published: February 2008

A theoretical, approximate solution is presented for steady rainfall or steady irrigation water seeping into ditch and tile drains in soil when the rainfall water is reinforced by the simultaneous upward seepage of artesian water. In the approximation it is assumed that the head loss in the narrow portion of the flow region above the lowest point of the water table arch is negligible. Utilizing a derived potential function and stream function, flow nets are presented for different rainfall and artesian flow conditions and for the drains running full and half full. A table of numerical values is presented for computing maximum water table heights. The theory is for an artesian basin at finite depth; for infinite depth, others have solved the problem for heights of water tables but not for flow nets. (Key words: Drainage; groundwater; artesian flow; irrigation)
Geohydrologic use of lithofacies maps in glaciated areas
Authors: Pettyjohn Wayne A. , Randich P. G.
Published: February 2008

Subsurface conditions may differ considerably from conditions indicated by surficial geologic maps, particularly in glaciated areas. Therefore, it is advantageous to use a series of lithofacies maps as a sequence of overlays plotted on transparent paper. Such maps permit direct visual determination of the lithology and areal extent of aquifers and indicate areas of possible stream losses or gains. They indicate areas and boundaries of confining layers and, in some places, they may be used to delineate areas of water‐table and artesian conditions. They are especially useful in determining buried channels in glaciated areas. The porosity of rock units making up an aquifer may be plotted on a lithofacies map, and the product of the volume of each lithologic type and the porosity provides an estimate of the total water in storage. In addition, if the water‐bearing properties are known, the quantity of water moving through an aquifer and the amount available to wells may be determined. Lithofacies maps also aid in the explanation of complex changes in water quality.
Rapid field measurement of air entry value and hydraulic conductivity of soil as significant parameters in flow system analysis
Authors: Bouwer Herman
Published: February 2008

Field measurements of air entry value and hydraulic conductivity of soil are obtained with a covered cylinder infiltrometer equipped with standpipe and vacuum gage. Tests are normally completed in approximately 30 minutes. The resulting data are used to construct step functions relating hydraulic conductivity to (negative) soil water pressure for sorption and desorption. These functions may be used as simplified hydraulic conductivity characteristics to include negative‐pressure flow in the analysis of subsurface water movement. Several field and laboratory studies demonstrate the validity of the concepts and the technique.
Forest protection and streamflow from an Adirondack Watershed
Authors: Eschner Arthur R. , Satterlund Donald R.
Published: February 2008

On the Sacandaga River watershed above Hope, New York, a slow one‐directional change in land use and an increase in forest cover have been correlated with a decrease in average annual, dormant season, and April runoff over the 39‐year period from 1912 to 1950. In 1912, total forest stand density and the density of conifers on the watershed were probably as low as they had ever been, after widespread logging, insect attacks, and a series of fires. As the beaver population increased explosively from 10 individuals to 20,000 individuals and forest density and crown cover of conifers increased up to 1950, the average annual streamflow decreased 7.72 inches, largely as a result of a 5.18‐inch decrease in dormant season runoff. April was the only month showing a large enough decrease in runoff (2.98 inches) to be statistically significant. Also, the average length of time it took for the most concentrated one‐half of the annual streamflow to run off increased by 19 days, from 67 to 86 days. The storm of November, 1950, disrupted the associated patterns of forest stand development and streamflow change, returning both to a point nearer their 1912 levels. Continuing mortality of trees weakened or exposed by the storm damage had not permitted the re‐establishment of any well defined pattern (by 1962) in either stand development or streamflow, although the changes in quantity and timing of flow parallel the changes in vegetation and largely verify the relationships inferred for the previous period.
The measurement of entrapped gas in the study of unsaturated flow phenomena
Authors: Debacker Louis W.
Published: February 2008

A method for the measurement of entrapped gas as a means of investigation of the unsaturated flow phenomena consists of two simultaneous measurements made with an apparatus combining an air‐pycnometer to obtain the volume of the free gas phase and a pressure cell with which the water outflow or inflow volume is measured. By difference the volume of entrapped gas is calculated. Results obtained on glass beads show that gas entrapment occurs mainly during the wetting of the sample, reaching a maximum entrapped gas content of about 6% of the total sample volume. The possibilities offered by the method are similar to those of the pressure cell, with the advantage that the amount of entrapped gas is known. Consequently, the influence of entrapped gas on capillary conductivity and water diffusivity can be investigated in drainage and infiltration studies.
Thermal influence on flow from a compressible porous medium
Authors: Passwell Robert E.
Published: February 2008

The equation of transient flow through a porous medium is dependent upon both the permeability and compressibility of the matrix, two properties that are highly temperature dependent. By formulating this dependence, it is possible to predict the behavior of a consolidating mass subject to specific constant temperature levels. This analysis is extended to predict transient flow behavior for conditions of temperature variations in a given sample, using numerical methods. Temperature increases induced either before or after dissipation of the excess hydrostatic pressure influence the rate of consolidation by increasing the rate of pore pressure dissipation and decreasing the ability of the matrix to assume the stress. An experimental program was established to study the effect of boundary temperature increases on a stressed‐saturated clay after pore pressure dissipation. Temperature increases caused immediate volume changes, the magnitudes being primarily dependent upon the magnitude of the temperature change. The magnitude of the initial stress (pore‐pressure excess) was seen to have a secondary effect on the magnitude of the volume change. These volume changes are attributed to a transfer of stress between the pore fluid and the matrix, as the increases in temperature increase the pore pressure but decrease the matrix strength.
Flood control alternatives and the economics of flood protection
Authors: Lind Robert C.
Published: February 2008

This paper discusses and compares the economic effects of alternative programs for coping with flood losses. Special emphasis is placed on the use of flood insurance. Also, the measurement of land‐enhancement benefits is discussed in some detail. (Key words: Economics; flood control; insurance)
Relations between topography and annual precipitation in western Oregon and Washington
Authors: Schermerhorn Vail P.
Published: February 2008

Average annual precipitation in western Oregon and Washington varies from less than 20 inches to over 150 inches, in obvious general relation to the topographic influences of the Coast and Cascade mountain ranges. If these influences could be isolated and measured, it would result in better definition of the precipitation resource in the mountainous areas of sparse measurements. Testing of the parameters and methods used by investigators in other regions led to the development of simple indexes to terrain elevation and barrier elevation. Together with a latitude index, they explain most of the variation in precipitation among the more than 280 stations. The key to the method is in the empirical definition of the contours of ‘effective’ barrier elevation. The pattern of residual errors from the graphical correlation shows no need for the usual zone parameter.
A note on the symmetry between bribes and charges
Authors: Plott Charles R. , Mestelman Stuart
Published: February 2008

It has been argued that within a dynamic setting, without complete information, the tax and bribe methods of correcting externalities give asymmetrical results. A model is presented which shows that the bribe alternative under such conditions yields optimal results, whereas the tax alternative does not. This conclusion is the opposite of conclusions drawn from other models advanced in the literature on the subject. It cannot be said that within such a setting one policy is better than the other, since all such conclusions depend upon the particular characteristics of each model.
A Mathematical Model for Simulating the Hydrologic Response of a Watershed
Authors: Huggins L. F. , Monke E. J.
Published: February 2008

A general mathematical model was developed to simulate the surface runoff from watersheds. Based upon the integration of the concepts of physical hydrology into quantitative relationships, the model avoids the use of lumped parameters by delineating the watershed as a grid of small, independent elements. Because of the resultant freedom from fundamental assumptions regarding the form of the system equations and from the permissible small areal resolution of the model, very complex combinations of watershed and storm conditions may be studied. Application of the model to two very small watersheds indicated a need for additional research to define better the relationships for surface runoff and infiltration to improve the reliability of the simulated runoff hydrographs.
Soil Hydraulic Conductivity as Affected by Sodic Water
Authors: Yaron Bruno , Thomas Grant W.
Published: February 2008

The hydraulic conductivities of soil‐glass bead mixtures in columns were determined during the flow of dilute sodium‐calcium solutions through the mixtures. Flow was continued until equilibrium was achieved. A curvilinear decrease in hydraulic conductivity was found as the exchangeable sodium approached equilibrium. The shape of the curve depended on the nature of the soil and the cationic composition and total salt content of the solutions. The hydraulic conductivity became constant only when a constant exchangeable sodium content was achieved along the soil column. A semiempirical method of predicting the hydraulic conductivity was developed. Agreement between calculated and observed values was found to be reasonably good.
Soil Moisture Availability for Transpiration
Authors: Molz F. J. , Remson Irwin , Fungaroli A. A. , Drake R. L.
Published: February 2008

Potential transpiration is a measure of the rate at which water can be transmitted from evaporation sites in plant leaves to the atmosphere. Potential soil‐moisture availability is defined as a measure of the capacity of a soil to transmit water to a root site. A differential equation is presented describing radial flow of soil moisture to a single vertical sink (root) in an infinite soil mass which is initially at a uniform moisture content. The relationship between moisture content and diffusivity for the soils studied may be represented by an exponential function. A numerical solution of the differential equation is used to determine the soil‐moisture flux. The results show that for specific soils the decrease in soil moisture with time occurs mainly in the immediate vicinity of the sink. Moisture flux increases with initial moisture content but is essentially time independent. In natural systems the flux would probably decrease with time because of multiple root interference. At large soil‐moisture contents, actual transpiration is limited by and equivalent to potential transpiration. At small soil‐moisture contents, actual transpiration is limited by and equivalent to potential soil‐moisture availability. (Key words: Evapotranspiration; plants; soil moisture)
Clogging and Contamination Processes in Recharge Wells
Authors: Rebhun M. , Schwarz J.
Published: February 2008

Artificial recharge of production wells by water from a lake is practiced in Israel on a large scale. The observed clogging of recharge wells and contamination of water pumped in dual purpose wells are attributed to small concentrations of organic suspended matter in recharge water. Processes surveyed in the field and simulated in a laboratory column system lead to the conclusion that organics are filtered out near the recharging well, reducing hydraulic conductivity in fine textured aquifers. Bacterial contamination and organic material decomposition are inhibited until recharge termination, as growth control components are present in recharge water. A short time after recharge termination (about 2 days) conditions become favorable to organic material decomposition and bacterial growth. High coliform bacteria counts are observed for about 50 days. To avoid the difficulties encountered, it is suggested that recharge wells be redeveloped by small volume pumpage.
Permeability of Sand with Dispersed Clay Particles
Authors: Denson Keith H. , Shindala Adnan , Fenn Charles D.
Published: February 2008

Montmorillonite clays in amounts above 3% by weight may be expected to reduce effective permeability of pure sands to fresh water by 100% or to practically zero for sands with the grain size distribution with mean of 0.30 mm and standard deviation of 0.18 mm. Kaolinite clays in amounts above 16% by weight may be expected to reduce the permeability of similar sands to practically zero.
A Note on the Average Probability of Extreme Events
Authors: Appel Charles A.
Published: February 2008

In a recent paper, Benson [1967] has shown that the limiting value of the average probability of all floods above the k‐year flood is equal to 1/2k; when the California, Weibull, or Hazen formulas are used to determine plotting positions. The purpose of this article is to show that the limiting value of the average probability is 1/2k; for any plotting‐position‐probability formula of the form
p = (m + a) /(n + b) where m is the rank with the highest value taken as 1, n is the number of ranked events, and a and b can be selected arbitrarily, except that b cannot be a negative integer.

Table 1, adapted from Chow [1964], gives some important plotting‐position formulas.
John Keill's View of the Hydrologic Cycle, 1698
Authors: White George W.
Published: February 2008

In the latter part of the 17th century a number of men in England were becoming impressed by the extent of sedimentary strata and by the presence of fossil shells in them. They realized that the material had been deposited in water at a time when the seas had different boundaries. Many thought that the greater extent of the seas had been only ephemeral and was related to the Noachian Deluge; they assumed that the waters rose very rapidly and persisted for only a short time.

Among these writers was Thomas Burnet, whose work on Sacred Theory of the Earth., first published in 1681, went through many editions in several languages in the next 20 or 30 years. William Whiston, in his New Theory of the Earth [1686], was concerned with the same matters, as was John Woodward, in his An Essay Towards a Natural History of the Earth [1695].
The vertical movement water in stratified porous material: 1. Infiltration
Authors: Childs E. C. , Bybordi M.
Published: February 2008

The infiltration law of Green and Ampt has long been established as an adequate approximation in uniform soil profiles. It is here extended to include heterogeneous profiles. Formulas are developed to express three relationships. Firstly, the infiltration law is derived for a profile consisting of a succession of n different layers with conductivity decreasing from the surface. Secondly, an expression is derived for the conductivity profile that will give a specified infiltration law, and in particular a linear infiltration law with specified parameters. Thirdly, this expression serves to determine the conductivity when the infiltration law is observed. Experiments are described to measure the infiltration rates into layered columns or porous material, the results of which confirm the theory.