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Federal land managers along with local stakeholders in the Upper Animas River watershed near Silverton, Colorado are actively designing and implementing mine waste remediation projects to mitigate the effects of acid mine drainage from several abandoned hard rock metal mines and mills. Local source rocks with high acid neutralization capacity (ANC) within the watershed are of interest to land managers for use in these remediation projects. A suite of representative samples was collected from propylitic to weakly sericitic-altered volcanic and plutonic rocks exposed in outcrops throughout the watershed. Acid-base accounting laboratory methods coupled with mineralogic and geochemical characterization provide insight into lithologies that have a range of ANC and net acid production (NAP). Petrophysical lab determinations of magnetic susceptibility converted to estimates for percent magnetite show correlation with the environmental properties of ANC and NAP for many of the lithologies. A goal of our study is to interpret watershed-scale airborne magnetic data for regional mapping of rocks that have varying degrees of ANC and NAP. Results of our preliminary work are presented here.

SUMMARY In order to investigate sequences of mine tailings that have settled in the bed of the Coeur d’Alene River, we improvised ways to make geophysical measurements on the river floor. To make ground penetrating radar (GPR) profiles, we mounted borehole antennas on a skid that was towed along the river bottom. To make induced polarization (IP) profiles, we devised a bottom streamer from a garden hose, Pb strips, and insulated wire. Both expedients worked well. GPR showed shallow stratigraphy, but did not directly detect the presence of contaminating metals. IP showed a zone of high chargeability that is probably due to pockets of relatively higher metal content. Neither method was able to define the base of the fluvial tailings section. BACKGROUND Starting in 1884, Pb-Zn-Ag was produced from the historic Coeur d’Alene mining district, ID (Hobbes and Fryklund, 1968). Tailings from the old mining operations have often flushed down the Coeur d’Alene River, especially during times of heavy winter floods, depositing in the river channel, flood plain, and on the bottom of Lake Coeur d’Alene as far as 50 miles away. These fluvial deposits are reworked by each big flood, and some contain enough’heavy metals, Pb in particular, to be dangerous to organisms that ingest the sediment. Box and others (1994) discuss some of the resulting environmental problems and prospects for their remediation. Drilling and assaying are reliable for investigating the fluvial tailings from spot to spot, but are slow, difficult, and expensive. A good, fast, and cheap method is needed to map their location, thickness, and compositions. This paper reports on tests we made to do that using ground penetrating radar (GPR) and Induced Polarization (IP). LABORATORY MEASUREMENTS Before going to the field, we measured samples from cores of river-bottom sediments at Colorado School of Mines Petrophysical Laboratory (Roth, 1996). The samples included pre-mining river bottom materials, as well as two kinds of sediments containing fluvial mine tailings: deeper tailings from the early mining days that often contain unrecovered metal ore; and shallower tailings from flotation mills introduced in the 192Os, which typically contain relatively lower metal concentrations. Seven of the 11 samples (Fig. 1) were from a sequence including all three of the above-described types, taken from a single corehole, 95PCK-1 (location shown on Fig. 4). The remaining 4 samples were from other coreholes in the Coeur d’Alene river bed. Samples marked (8~) on Fig. 1 are pre-mining sediments that contain negligible metals. The two samples marked (!) contain especially high metals; the one from 297-326 cm depth contained over 5% Pb and Zn, and that from 262-297 cm depth had about 3% Pb and Zn. The remaining, still-shallower, fluvial tailings from 95PCK-1 contained about 1% total Pb and Zn. Fig. 1 shows measured values of relative dielectric permittivity (RDP) and of resistivity for the 11 samples. The figure shows that RDP tends to increase with depth over the measured interval of 95PCK- 1, and that resistivity is generally low there. At other places, where the pre-mining sediments are sandier and less silty or clayey, resistivities are much higher. The generally-low resistivities at the 95PCK-1 site probably arise from high amounts of dissolved metals in the pore water, and were bad news to us, for they meant that GPR penetration depths there would be limited. There is a vague tendency in this sample set for RDP to go up as particle size goes down. This indicated to us that GPR might be

Subsurface contamination of shallow aquifers by brine has occurred at the Brookhaven (MS) oil field as a part of past oil production activities. A research project funded by the Environmental Protection Agency (EPA) has successfully used Helicopter Electromagnetic (HEM) methods to map possible areas of high subsurface brine contamination. Geographic Information System @IS) computer programs have been effectively used to integrate various geologic, demographic, hydrologic, and geophysical digital data sets. Maps of apparent resistivity do.) produced by the contractor’s processing of the HEM data reveal only weak influences of metallic cultural features that severely hamper the use of ground electrical and electromagnetic surveys. Additional processing of the data yielded contour maps of interpreted resistivity (p,) at various depth slices within the maximum depth of exploration for the HEM measurement (about 50 meters). The depth slice for 30 meters shows distinct resistivity lows spatially correlated with brine disposal pits identified during site inspections. Low values of pr can be caused by either high brine contamination or clay layers in the subsurface.

Fluvial and shallow marine sediments have undergone significant and varied diagensis during shallow burial in the Coalinga and Jacalitos oil fields. Calcite and dolomite cements are present in some sands. Calcite cementation generally occurred early and influenced subsequent diagenesis, including dolomitization and replacement of framework grains by carbonates. Where calcite cementation did not occur, volcanics and feldspars were extensively altered to clays and compaction destroyed most primary porosity. Dissolution of grains and cements then created secondary porosity into which oil migrated and accumulated.

The West Shasta copper-zinc district, Shasta County, California, contains many volcanogenic sulfide deposits within Middle Devonian rhyolites that have not been highly metamorphosed. The district was selected by the U.S. Geological Survey for intensive geological, geochemical, and geophysical study under the Development of Assessment Techniques (DAT) project because accessible exposures have been created by erosion and mining. This report describes the geophysical methods applied to characterize the electrical properties of selected West Shasta massive sulfide deposits and their host rocks, at both small (less than 25 ft) and large (greater than 25 ft) scales. The electrical techniques used galvanic (spectral induced polarization--SIP) and induction (very low frequency--VLF, slingram, and time domain electro-magnetics--TDEM) methods.In situ spectral induced polarization measurements were carried out to determine whether or not conductive anomalies in the district could be differentiated by their polarization signatures. The sulfide, in situ, induced polarization-phase spectral signatures (the induced polarization effect as a function of frequency) have much less character and lack the distinctive shape reported for other massive sulfide deposits; however, they do have some identifiable massive sulfide traits, such as low resistivity and variable polarizability. The nondescript sulfide spectral signature is attributed to the poor development of polarization processes due to a high percentage of resistive, nonpolarizable gangue minerals, lack of pore space, and limited electrolytic fluids. Large-scale spectral induced polarization measurements over the Hornet orebody have a greater polarization than the in situ measurements. This observation, in addition to the fact that much of the Hornet sulfide body has been removed by previous mining activity, suggests that the dominant polarization processes occur at the ground-water-sulfide interface.Combined use of induction techniques, which have different depths of penetration, were used to locate conductive anomalies and determine their shape and depth. All the induction surveys over the Hornet orebody detected the conductive tabular-shaped massive pyritic sulfide deposit hosted in resistive rhyolite. Shallow penetrating induction methods near the Keystone mine detected a conductive fault zone where a block of shale has been downfaulted into volcanic rock. Integrated interpretation of deeper penetrating induction data over this conductive fault zone indicates that parts of the shale are also conductive, demonstrating that the integrated use of several induction methods provides better conductor definition than a single method.

In planning deep subsurface structures such as tunnels and mines, it is desirable to form some idea in advance as to the amount of water which will probably be encountered and will require removal. Isolated test shafts are costly, and may not show average conditions. It is desirable to supplement such special data by considerations based on general experience as to the yield of underground water under similar conditions. Data can generally be secured as to the yield of shallow or surface wells overlying the region where the underground structure is to be made. Such data have been published concerning many conditions and kinds of rock as to the average and usual range of yields of surface wells under different conditions. It is the purpose here to present a method and formula by which data obtained from surface wells can be applied, under suitable conditions, to the estimation of the amount of water which it may reasonably be expected will be encountered in any deep excavation. The method is limited to cases where the bed rock is somewhat uniform in character throughout all depths from the rock floor down to the bottom of the tunnel or other structure. For example, the method will apply to the estimation of probable water in a tunnel in granite, which extends to the surface, but will not apply to a tunnel in deep-seated granite overlain by thick beds of sedimentary rocks. Without giving details it may be said that there are physical reasons, well confirmed by statistics and experience, showing that the frequency and water-carrying capacity of fissures, joint openings and solution channels in rocks decreases rapidly as the depth increases.

It happens that twenty-five years ago two publications appeared dealing with the valuation of riparian rights and the determination of diversion damages. The first paper, which was by the present author,1 dealt with engineering practice in water power valuation as of that date. The second publication referred to was the report of the Committee of the New England Water Works Association on Data Relating to Awards for Water and Water Power Diversion.2 It contained data regarding prices paid and awards made in the acquisition of riparian rights and diversion damages for water supply purposes in over two hundred cases, representative of conditions throughout a period of about thirty years prior to the date of the report. The present paper is mainly devoted to a consideration of engineering and economic changes in water power practice during the subsequent quarter of a century in relation to their effect on water power valuation and the cost of acquisition of diversion rights. The general principles and practice of water rights valuation were set forth in the author's preceding paper above referred to and will not be repeated except insofar as necessary to make the present paper reasonably self-contained and to provide a background for discussion of the effect of changes in conditions in the subsequent period.

Time required for a well to reach equilibrium with constant draught. It not infrequently occurs where wells are used for public water supply or for irrigation that there is a progressive depression of the water table, sometimes continuing for years. It is evident that a new well might derive an initially large but ever decreasing supply from connate water, even with no infiltration. In general, with constant draught and infiltration, the well will reach equilibrium when

Immature lower to middle Miocene marine sandstones constitute important reservoir rocks in many southern San Joaquin basin oil fields. Surface samples from the east and west margins of the basin and subsurface samples from Round Mountain, Belridge, and Coalinga fields were examined. These localities have undergone recurrent uplift since middle Tertiary time and maximum burial probably did not exceed 2500-3000 m. Diagenetic features common to east- and west-side sandstones include phosphatization, early calcite cementation, pressure solution and replacement of silicate grains by calcite cement, framework grain dissolution and creation of secondary porosity, and replacement of biotite and hornblende by chlorite. Differences include recrystallization and dolomitization of early calcite on the west side, and massive carbonate dissolution followed by extensive crushing and pressure solution of silicate grains and late replacement of plagioclase by calcite and calcite by hematite on the east side. Replacement of biotite by chlorite occurred only in the deepest samples on either side of the basin. Basinwide differences in diagenesis reflect different tectonic evolutions between east and west sides of the basin. Local variations in diagenetic patterns are pronounced in all areas and are controlled by initial sediment composition. For example, in one core from Coalinga early calcitemore » cement, recrystallized calcite cement, and dolomitized calcite cement are interbedded over the 60-m interval sampled. Hydrocarbons in all samples reside mainly in secondary pores created by cement and framework-grain dissolution, underscoring the importance of diagenesis in creating reservoirs in this basin.« less

Newly developed airborne geophysical data processing methods and instrumentation have been applied in a study of the Effie-Coon Lake area of northern Minnesota. The objective of this study is to demonstrate application of emerging technology to mineral resource evaluation of areas where bedrock is largely concealed by glacial cover. Total magnetic field data were processed with recently developed methods to enhance interpretation of bedrock lithology. Airborne electromagnetic (AEM) instrumentation developed by the USGS was flown along with a standard airborne magnetic sensor. Very Low Frequency (VLF) measurements at about 20 kHz have been used to make an apparent resistivity map. This map can be used to interpret depth to bedrock and conductivity variations of the glacial cover. A recently developed AEM system measures signals radiating from powerlines at 60, 180, and 300 Hz. The 60 Hz data are least susceptible to screening by the glacial drift even where it is over 100 m thick. Apparent resistivities have also been computed from these measurements. Bedrock conductive zones, identified by these data, correlate well with commercial ground and AEM survey data. However, there is some suggestion that the conductive zone may be somewhat larger than what was previously mapped.

The composition of the stream system of a drainage basin can be expressed quantitatively in terms of stream order, drainage density, bifurcation ratio, and stream-length ratio. Stream orders are so chosen that the fingertip or unbranched tributaries are of the 1st order; streams which receive 1st order tributaries, but these only, are of the 2d order; third order streams receive 2d or 1st and 2d order tributaries, and so on, until, finally, the main stream is of the highest order and characterizes the order of the drainage basin. Two fundamental laws connect the numbers and lengths of streams of different orders in a drainage basin: The infiltration theory of surface runoff is based on two fundamental concepts: For a given terrain there is a minimum length x c of overland flow required to produce sufficient runoff volume to initiate erosion. The critical length x c depends on surface slope, runoff intensity, infiltration-capacity, and resistivity of the soil to erosion. This is the most important single factor involved in erosion phenomena and, in particular, in connection with the development of stream systems and their drainage basins by aqueous erosion. The erosive force and the rate at which erosion can take place at a distance x from the watershed line is directly proportional to the runoff intensity, in inches per hour, the distance x , a function of the slope angle, and a proportionality factor K e , which represents the quantity of material which can be torn loose and eroded per unit of time and surface area, with unit runoff intensity, slope, and terrain. The rate of erosion is the quantity of material actually removed from the soil surface per unit of time and area, and this may be governed by either the transporting power of overland flow or the actual rate of erosion, whichever is smaller. If the quantity of material torn loose and carried in suspension in overland flow exceeds the quantity which can be transported, deposition or sedimentation on the soil surface will take place. On newly exposed terrain, resulting, for example, from the recession of a coast line, sheet erosion occurs first where the distance from the watershed line to the coast line first exceeds the critical length x c and sheet erosion spreads laterally as the width of the exposed terrain increases. Erosion of such a newly exposed plane surface initially develops a series of shallow, close-spaced, shoestring gullies or rill channels. The rills flow parallel with or are consequent on the original slope. As a result of various causes, the divides between adjacent rill channels are broken down locally, and the flow in the shallower rill channels more remote from the initial rill is diverted into deeper rills more closely adjacent thereto, and a new system of rill channels is developed having a direction of flow at an angle to the initial rill channels and producing a resultant slope toward the initial rill. This is called cross-grading. With progressive exposure of new terrain, streams develop first at points where the length of overland flow first exceeds the critical length x c , and streams starting at these points generally become the primary or highest-order streams of the ultimate drainage basins. The development of a rilled surface on each side of the main stream, followed by cross-grading, creates lateral slopes toward the main stream, and on these slopes tributary streams develop, usually one on either side, at points where the length of overland flow in the new resultant slope direction first exceeds the critical length x c . Cross-grading and recross-grading of a given portion of the area will continue, accompanied in each case by the development of a new order of tributary streams, until finally the length of overland flow within the remaining areas is everywhere less than the critical length x c . These processes fully account for the geometric-series laws of stream numbers and stream lengths. A belt of no erosion exists around the margin of each drainage basin and interior subarea while the development of the stream system is in progress, and this belt of no erosion finally covers the entire area when the stream development becomes complete. The development of interior divides between subordinate streams takes place as the result of competitive erosion, and such divides, as well as the exterior divide surrounding the drainage basin, are generally sinuous in plan and profile as a result of competitive erosion on the two sides of the divide, with the general result that isolated hills commonly occur along divides, particularly on cross divides, at their junctions with longitudinal divides. These interfluve hills are not uneroded areas, as their summits had been subjected to more or less repeated cross-grading previous to the development of the divide on which they are located. With increased exposure of terrain weaker streams may be absorbed by the stronger, larger streams by competitive erosion, and the drainage basin grows in width at the same time that it increases in length. There is, however, always a triangular area of direct drainage to the coast line intermediate between any two major streams, with the result that the final form of a drainage basin is usually ovoid or pear-shaped. The drainage basins of the first-order tributaries are the last developed on a given area, and such streams often have steep-sided, V-shaped, incised channels adjoined by belts of no erosion. The end point of stream development occurs when the tributary subareas have been so completely subdivided by successive orders of stream development that there nowhere remains a length of overland flow exceeding the critical length x c . Stream channels may, however, continue to develop to some extent through headward erosion, but stream channels do not, in general, extend to the watershed line. Valley and stream development occur together and are closely related. At a given cross section the valley cannot grade below the stream, and the valley supplies the runoff and sediment which together determine the valley and stream profiles. As a result of cross-grading antecedent to the development of new tributaries, the tributaries and their valleys are concordant with the parent stream and valley at the time the new streams are formed and remain concordant thereafter. Valley cross sections, when grading is complete, and except for first-order tributaries, are generally S-shaped on each side of the stream, with a point of contraflexure on the upper portion of the slope, and downslope from this point the final form is determined by a combination of factors, including erosion rate, transporting power, and the relative frequencies of occurrence of storms and runoff of different intensities. The longitudinal profile of a valley along the stream bank and the cross section of the valley are closely related, and both are related to the resultant slope at a given location. Many areas on which meager stream development has taken place, and which are commonly classified as youthful, are really mature, because the end point of stream development and erosion for existing conditions has already been reached. When the end point of stream and valley gradation has arrived in a given drainage basin, the remaining surface is usually concave upward, more or less remembling a segment of a parabaloid, ribbed by cross and longitudinal divides and containing interfluve hills and plateaus. This is called a “graded” surface, and it is suggested that the term “peneplain” is not appropriate, since this surface is neither a plane nor nearly a plane, nor does it approach a plane as an ultimate limiting form. The hydrophysical concepts applied to stream and valley development account for observed phenomena from the time of exposure of the terrain. Details of these phenomena of stream and valley development on a given area may be modified by geologic structures and subsequent geologic changes, as well as local variations of infiltration-capacity and resistance to erosion. In this paper stream development and drainage-basin topography are considered wholly from the viewpoint of the operation of hydrophysical processes. In connection with the Davis erosion cycle the same subject is treated largely with reference to the effects of antecedent geologic conditions and subsequent geologic changes. The two views bear much the same relation as two pictures of the same object taken in different lights, and one supplements the other. The Davis erosion cycle is, in effect, usually assumed to begin after the development of at least a partial stream system; the hydrophysical concept carries stream development back to the original newly exposed surface.

Introduction-synopsis—This paper describes a method which may be used for determining the average infiltration-capacity over a drainage-basin during large storms where a runoff-record, together with adequate rainfall-data, are available. The application of the method requires that in each drainage-basin there shall be at least one rain-intensity record kept with a recording rain-gage. The method is based on the observed fact that in great general storms, while there may be two or more different types of rain-intensity graphs in different parts of the storm-area, locally the rain-intensity graphs are statistically very much alike.

Rainfall in a given locality is governed by two sets of factors: (1) Hydrodynamic factors, such as topography and orographic conditions, which, together with atmospheric circulation, general and local, determine the occurrence and frequency of ascending air-masses; (2) moisture-supply. Either of these factors may be adequate to produce rain but if the other is deficient, little or no rain occurs. Air-masses rich in moisture pass in summer from the Pacific Ocean over the coastal plains of California, producing little or no rain until forced above the condensation-level by the coastal mountain ranges.

Factors descriptive of a drainage-basin as related to its hydrology may be classified broadly as: (1) Morphologic—These factors depend only on the topography of the land forms of which the drainage-basin is composed and on the form and extent of the stream-system or drainage-net within it. ((2) Soil factors—This group includes factors descriptive of the materials forming the groundwork of the drainage-basin, including all those physical properties involved in the moisture-relations of soils. (3) Geologic-structural factors—These factors relate to the depths and characteristics of the underlying rocks and the nature of the geologic structures in so far as they are related to ground-water conditions or otherwise to the hydrology of the drainage-basin. (4) Vegetational factors—These are factors which depend wholly or in part on the vegetation, natural or cultivated, growing within the drainage-basin. (5) Climatic-hydrologic factors—Climatic factors include: Temperature, humidity, rainfall, and evaporation, but as humidity, rainfall, and evaporation may also be considered as hydrologic, the two groups of factors have been combined. Hydrologic factors relate specially to conditions dependent on the operation of the hydrologic cycle, particularly with reference to runoff and ground-water.

Water-losses equal the difference between rainfall and runoff. Most determinations of runoff have been made in middle latitudes and at low to medium elevations above sea-level. Most of our factual knowledge of water-losses is limited to such regions. Knowledge of water-losses in high latitudes is of scientific importance in relation to problems of ecology and polar climatology. Knowledge of water-losses at high elevations is important in a variety of ways. The best and often the only economic use of high mountain areas is to supply water to lower regions. Knowledge of water-losses at high elevations is of scientific interest, for example, in relation to the perplexing problems of the alimentation of mountain glaciers and in relation to the ecology and tonal distribution of vegetation.