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USGS1949

Ground-water supplies of the Ypsilanti area, Michigan

As of the date of this report (August 1945), the major water users in the Ypsilanti area are: (1) the city of Ypsilanti, (2) the Willow Run bomber plant, built by the Federal Government and operated by the Ford Motor Co., and (3) the war housing project of the Federal Public Housing Authority, designated in this report the Willow Run Townsite. The city, bomber plant, and townsite have required large quantities of water for domestic and industrial uses, and the necessary water supplies have been developed from wells. The Federal Works Agency had the responsibility of deciding whether the existing water facilities were adequate to meet the expected demands and determining the character of any additional public water-supply facilities that might be constructed with Federal assistance. In order to appraise the ground-water resources of the area the Federal Works Agency requested the Geological Survey to investigate the adequacy of the existing supplies and the availability of additional water. The present report is the result of the investigation, which was made in cooperation with the Michigan Geological Survey Division. The water supplies of the three major users are obtained from wells penetrating glacial and associated sands and gravels. Supplies for the city of Ypsilanti and the Willow Run bomber plant are obtained from wells in the valley of the Huron River; the supply for the Willow Run Townsite is obtained from wells penetrating glacial gravels underlying the upland northeast of the valley. The bedrock formations of the area either yield little water to wells or yield water that is too highly mineralized for most uses. The water supply for the bomber plant is obtained from three closely spaced, highly productive wells at the northern edge of the Huron River, a little more than 3 miles southeast of Ypsilanti. The water receives complete treatment in a modern treatment plant. River water also can be treated and has been used occasionally in the winter and spring. The average daily pumpage during periods of maximum production at the bomber plant has been 4.5 to 4.75 million gallons. On June 30, 1945, production of bombers was suspended, and the plant went on a. maintenance basis. The water supply of the bomber-plant well field is replenished by recharge from precipitation and from the Huron River. The evidence shows that recharge from the river is one of the principal sources of water and gives assurance both of the adequacy of the present supply and of the availability of additional water if needed. The safe yield of the three existing wells is estimated to be not less than 6 million gallons per day. The Ypsilanti public water supply is obtained from three tubular wells drilled in 1943, which replaced a number of suction-pumped tubular wells and one large dug well. All the wells penetrate sand and gravel in the bend of the Huron River in the southeastern part of Ypsilanti. The water is treated in a modern treatment plant completed in 1939. The average daily pumpage in million gallons was about 1.68 in 1942, 1.70 in 1943, and 1.66 in 1944. Considerable water was furnished to the Willow Run bomber plant from the Ypsilanti public-supply system during the period from August 1941 through March 1943. The available information indicates that the water pumped from the Ypsilanti well field is replenished by ground-water flow from adjacent stretches of the Huron Valley and from the upland areas outside the valley, from precipitation on the valley in the vicinity of the well field, and possibly from the Huron River. It is believed that sufficient water can be obtained from the well field to meet the expected demand for a considerable time. The safe yield of the present wells is estimated to be not less than 3 million gallons per day, and detailed pumping tests might show that still larger supplies could be safely developed. The water supply of the Willow Run Townsite is obtained from four wells in two well fields about 2 miles apart, one well in the northwest or Prospect and Geddes Road field, and three wells in the southeast or Wiard Road field. The pumpage was originally expected to be 2 to 3 million gallons per day, but it averaged only about 450,000 gallons per day from March 1943 through June 1945. The evidence afforded by logs of wells and by pumping tests indicates that the water-bearing gravels at the townsite are covered by relatively impermeable materials and thus that the rate of recharge is low. However, only relatively small declines in water level have occurred during more than 2 years' operation of the wells, indicating that recharge may occur nearby. The safe yield of the present wells is estimated to be 1.0 to 1.5 million gallons per day, and detailed pumping tests might show it to be somewhat greater. The water supply of the Willow Run Townsite has the smallest potential capacity of the three major ground-water supplies in the area; however, the demand has been relatively small, and no difficulty should arise unless this demand increases greatly. The investigation involved the drilling of 13 test wells to locate additional ground-water supplies, on the assumption that the wartime demand for water in the Ypsilanti area might increase beyond the capacity of the present sources. All 13 wells were drilled at sites selected by the Geological Survey. Two wells on the Willow Run Townsite were drilled by the Federal Public Housing Authority and 11 at other sites by the Federal Works Agency. Records of the wells are given in the report and discussed with respect to the availability of water at the different sites; similarly, the results of the controlled pumping tests made on four of the test wells drilled by the Federal Works Agency are analyzed and discussed with respect to the availability of additional water. The combined results of the test drilling and the pumping tests show that emergency supplies of several million gallons per day can be developed at the sites of the test wells. The best site shown by the test drilling is on the south bank of the Huron River opposite the bomber-plant well field, where a Well with a capacity of several thousand gallons per minute could be constructed if necessary. Three wells in the outwash-filled valley now occupied by Fleming Creek, on two of which pumping tests were made, show that emergency supplies ranging from a few hundred thousand to a million gallons per day could be developed at these test-well sites if necessary. Smaller Supplies ranging from a gallon or two per minute to perhaps 100,000 or 200,000 gallons per day could be developed at the sites of the remaining test Wells. Pumping tests made on the supply wells of the three major water users by the consulting-engineering firms who designed the systems are analyzed and discussed briefly by the authors. The report includes maps and graphs showing the surficial geology of the area, the location of wells, and fluctuations of water level in selected wells. Alsp included are tables giving data on water levels and pumpage, chemical analyses of representative ground waters, and records of wells.

Michigan↗

USGS2025

Arctic fold-and-thrust belts

The modern Arctic has been formed through a series of continent–continent collisions, accretion of terranes and phases of crustal extension. The Neoproterozoic Timanian, Paleozoic Caledonian and Uralian, and late Mesozoic Verkhoyansk–Kolyma, Chukotkan and Brookian orogenies formed several large fold-and-thrust belts (FTBs). The FTBs are exposed across vast areas of continents and continue offshore to form a complex tectonic basement for thick sedimentary basins, playing an important role in the history of accumulation and deformation of younger unmetamorphosed sedimentary successions that are the subject of this volume. Recognition of the importance of FTBs in the Arctic geological history and their role as a controlling factor of development of Arctic sedimentary basins resulted in this chapter, in which we review the current state of knowledge about Arctic FTBs and highlight questions that remain to be addressed. Enclosure D , a map showing boundaries of the FTB and their internal first-order structural fabric, is a part of the overview.

Book chapter↗

USGS2025

An integrated sensor network and data driven approach to satellite remote sensing of dissolved organic matter

Traditional remote sensing retrieval models for water quality have historically relied on limited, localized data sets due to the prohibitive costs of extensive field campaigns and logistical challenges of collecting match-up data with satellite overpasses. As a result, these models often lack generalizability across seasons, tides, and sites. Furthermore, small field data sets limit the utility of modern machine learning techniques to advance remote sensing retrieval models. In situ optical sensors deployed in a sensor network to continuously monitor larger water bodies can drastically increase the number of measurements, providing the opportunity to develop new approaches for building robust remote sensing retrieval models by leveraging both remote sensing data and in situ networks as an integrated monitoring system. This study leverages a large “ground-to-space” sensor network that combines an in situ optical sensor network with satellite-based remote sensing to overcome these limitations. Utilizing a large-scale data set from the U.S. Geological Survey's Sacramento—San Joaquin River Delta monitoring network, of dissolved organic matter fluorescence measurements, and remote sensing data from the European Space Agency's Sentinel-2A and -2B satellites, this study implemented a data driven approach for dissolved organic matter models. The data set, consisting of 982 samples collected between 2018 and 2021 was used to train and validate a random forest model ( R 2 = 0.76, RMSE = 6.1 Quinine Sulfate Equivalents), with demonstrated applicability across diverse site conditions, tidal stages, and seasons. This work provides a scalable solution to address critical challenges in water quality monitoring and offers a replicable framework for global water quality management.

Calfornia↗

USGS1982

Geologic map of the Redwood Creek drainage basin, Humboldt County, California

A 1:62,500-scale geologic map with 14 rock stratigraphic units and an accompanying explanatory text are used to describe the geology of the Redwood Creek drainage basin of northwestern California. A large part of Redwood National Park is located in the downstream part of this actively eroding drainage basin. The bedrock consists primarily of Mesozoic sedimentary and metamorphic rocks. The structurally complex Franciscan assemblage of rocks underlies most of the basin, but rocks of the Klammath Mountain tectonic province occurs in a small eastern part of the basin. Most major boundaries between Mesozoic rock units are north-northwest trending faults parallel to the regional structural trend. Extensive areas of surficial coastal plain sediments, landslide deposits, stream terrace deposits and modern alluvium are also present; these areas help identify loci of vigorous recent erosion. (USGS)

California↗

USGS1955

Water requirements of selected industries

The early industries in America generally were established when and where demands for the products of industry arose. Most of the early industries were so located that their increasing requirements for transportation, raw materials, market, labor, and water supply could be satisfied economically. Many of these original plant locations have continued as modern industrial centers and their output has increased manyfold in meeting the demands of our growing Nation. The recent and current industrial expansion and the trend toward the growth of chemical industries, many Of which are heavy users of water, has resulted in a tremendous increase in the total withdrawal of water for industrial use as well as a large increase in the per capita use of water. This increase in industrial water requirement has strained the capacity of the developed water supplies in many areas, and in some instances the adequacy of the potential water supplies is questionable. The Geological Survey is engaged in preparing and publishing a series of reports describing the developed and undeveloped water resources of many important industrial areas. This work was started initially at the request of the National Securities Resources Board as a means to insure that water supplies are adequate for our rapidly expanding industrial development. Although many factors contribute to establishing the feasibility or even the limits of future industrial development, the one relating to available water supply is extremely important. A knowledge of the water requirements of various industries is valuable therefore in planning the logical development in any area where water supply is a critical factor. Thus far very little suitable information on the water requirements of our major industries is available for general planning. An inventory of unit water-use values in industry therefore would be generally helpful and also might tend to stimulate water-conservation methods. To obtain such information, investigations

Water Supply Paper↗

USGS2016

Stratigraphic architecture of a fluvial-lacustrine basin-fill succession at Desolation Canyon, Uinta Basin, Utah: Reference to Walthers’ Law and implications for the petroleum industry

A continuous window into the fluvial-lacustrine basin-fill succession of the Uinta Basin is exposed along a 48-mile (77-kilometer) transect up the modern Green River from Three Fords to Sand Wash in Desolation Canyon, Utah. In ascending order the stratigraphic units are: 1) Flagstaff Limestone, 2) lower Wasatch member of the Wasatch Formation, 3) middle Wasatch member of the Wasatch Formation, 4) upper Wasatch member of the Wasatch Formation, 5) Uteland Butte member of the lower Green River Formation, 6) lower Green River Formation, 7) Renegade Tongue of the lower Green River Formation, 8) middle Green River Formation, and 9) the Mahogany oil shale zone marking the boundary between the middle and upper Green River Formations. This article uses regional field mapping, geologic maps, photographs, and descriptions of the stratigraphic unit including: 1) bounding surfaces, 2) key upward stratigraphic characteristics within the unit, and 3) longitudinal changes along the river transect. This information is used to create a north-south cross section through the basin-fill succession and a detailed geologic map of Desolation Canyon. The cross section documents stratigraphic relationships previously unreported and contrasts with earlier interpretations in two ways: 1) abrupt upward shifts in the stratigraphy documented herein, contrast with the gradual interfingering relationships proposed by Ryder et al., (1976) and Fouch et al., (1994) , 2) we document fluvial deposits of the lower and middle Wasatch to be distinct and more widespread than previously recognized. In addition, we document that the Uteland Butte member of the lower Green River Formation was deposited in a lacustrine environment in Desolation Canyon. Two large-scale (member-scale) upward patterns are noted: Waltherian, and non-Waltherian. The upward successions in Waltherian progressions record progradation or retrogradation of a linked fluvial-lacustrine system across the area; whereas the upward successions in non-Waltherian progressions record large-scale changes in the depositional system that are not related to progradation or retrogradation of the ancient lacustrine shoreline. Four Waltherian progressions are noted: 1) the Flagstaff Limestone to lower Wasatch Formation member records the upward transition from lacustrine to fluvial—or shallowing-upward succession; 2) the upper Wasatch to Uteland Butte records the upward transition from fluvial to lacustrine—or a deepening upward succession; 3) the Uteland Butte to Renegade Tongue records the upward transition from lacustrine to fluvial—a shallowing-upward succession; and 4) the Renegade Tongue to Mahogany oil shale interval records the upward transition from fluvial to lacustrine—a deepening upward succession. The two non-Waltherian progressions in the study area are: 1) the lower to middle Wasatch, which records the abrupt shift from low to high net-sand content fluvial system, and 2) the middle to upper Wasatch, which records the abrupt shift from high to intermediate net-sand content fluvial system.

Utah↗

USGS2009

Methane sources in gas hydrate-bearing cold seeps: Evidence from radiocarbon and stable isotopes

Fossil methane from the large and dynamic marine gas hydrate reservoir has the potential to influence oceanic and atmospheric carbon pools. However, natural radiocarbon ( 14 C) measurements of gas hydrate methane have been extremely limited, and their use as a source and process indicator has not yet been systematically established. In this study, gas hydrate-bound and dissolved methane recovered from six geologically and geographically distinct high-gas-flux cold seeps was found to be 98 to 100% fossil based on its 14 C content. Given this prevalence of fossil methane and the small contribution of gas hydrate (??? 1%) to the present-day atmospheric methane flux, non-fossil contributions of gas hydrate methane to the atmosphere are not likely to be quantitatively significant. This conclusion is consistent with contemporary atmospheric methane budget calculations. In combination with ?? 13 C- and ??D-methane measurements, we also determine the extent to which the low, but detectable, amounts of 14 C (~ 1-2% modern carbon, pMC) in methane from two cold seeps might reflect in situ production from near-seafloor sediment organic carbon (SOC). A 14 C mass balance approach using fossil methane and 14 C-enriched SOC suggests that as much as 8 to 29% of hydrate-associated methane carbon may originate from SOC contained within the upper 6??m of sediment. These findings validate the assumption of a predominantly fossil carbon source for marine gas hydrate, but also indicate that structural gas hydrate from at least certain cold seeps contains a component of methane produced during decomposition of non-fossil organic matter in near-surface sediment.

Marine Chemistry↗

USGS2019

Crustal magmatism and anisotropy beneath the Arabian Shield - A cautionary tale

Volcanism in Saudi Arabia includes a historic eruption close to the holy city of Al Madinah. As part of a volcanic hazard assessment of this area, magnetotelluric (MT) data were collected to investigate the structural setting, the distribution of melt within the crust, and the mantle source of volcanism. Interpretation of a new 3‐D resistivity model includes a shallow graben beneath thin lava fields (Harrats), a melt‐free upper crust, and decompression melting in the asthenosphere below thin lithosphere. Within the lower crust the model images elongate conductivity anomalies, one of which was attributed in a previous MT study to melt. The regional MT data, combined with perspective from geology and geophysical modeling, suggest the lower crust is anisotropic with no interconnected melt zones. These divergent interpretations have distinct hazard implications and highlight the importance of large survey aperture and anisotropic modeling to MT studies of volcanic regions. Lower‐crustal anisotropy extends beyond the Harrat, with the most conductive direction oriented N10°E and a factor of 3–5, determined from 2‐D anisotropic inversion, between the most and least conductive directions. The enhanced conductivity is likely due to interconnected grain boundary graphite, while the anisotropy direction reflects either frozen‐in fabric from Neoproterozoic stabilization of the Arabian Shield or modern ductile deformation driven by channelized asthenospheric flow coupled through a thin rigid mantle lid. Asthenospheric melt is interpreted to transect the crust primarily through diking, with limited melt storage and short residence times in the crust.

Arabian Shield↗

USGS2007

GIS data for the Seaside, Oregon, Tsunami Pilot Study to modernize FEMA flood hazard maps

A Tsunami Pilot Study was conducted for the area surrounding the coastal town of Seaside, Oregon, as part of the Federal Emergency Management's (FEMA) Flood Insurance Rate Map Modernization Program (Tsunami Pilot Study Working Group, 2006). The Cascadia subduction zone extends from Cape Mendocino, California, to Vancouver Island, Canada. The Seaside area was chosen because it is typical of many coastal communities subject to tsunamis generated by far- and near-field (Cascadia) earthquakes. Two goals of the pilot study were to develop probabilistic 100-year and 500-year tsunami inundation maps using Probabilistic Tsunami Hazard Analysis (PTHA) and to provide recommendations for improving tsunami hazard assessment guidelines for FEMA and state and local agencies. The study was an interagency effort by the National Oceanic and Atmospheric Administration, U.S. Geological Survey, and FEMA, in collaboration with the University of Southern California, Middle East Technical University, Portland State University, Horning Geoscience, Northwest Hydraulics Consultants, and the Oregon Department of Geological and Mineral Industries. The pilot study model data and results are published separately as a geographic information systems (GIS) data report (Wong and others, 2006). The flood maps and GIS data are briefly described here.

Oregon↗

USGS2023

When less is more: How increasing the complexity of machine learning strategies for geothermal energy assessments may not lead toward better estimates

Previous moderate- and high-temperature geothermal resource assessments of the western United States utilized data-driven methods and expert decisions to estimate resource favorability. Although expert decisions can add confidence to the modeling process by ensuring reasonable models are employed, expert decisions also introduce human and, thereby, model bias. This bias can present a source of error that reduces the predictive performance of the models and confidence in the resulting resource estimates. Our study aims to develop robust data-driven methods with the goals of reducing bias and improving predictive ability. We present and compare nine favorability maps for geothermal resources in the western United States using data from the U.S. Geological Survey's 2008 geothermal resource assessment. Two favorability maps are created using the expert decision-dependent methods from the 2008 assessment ( i.e., weight-of-evidence and logistic regression). With the same data, we then create six different favorability maps using logistic regression (without underlying expert decisions), XGBoost, and support-vector machines paired with two training strategies. The training strategies are customized to address the inherent challenges of applying machine learning to the geothermal training data, which have no negative examples and severe class imbalance. We also create another favorability map using an artificial neural network. We demonstrate that modern machine learning approaches can improve upon systems built with expert decisions. We also find that XGBoost, a non-linear algorithm, produces greater agreement with the 2008 results than linear logistic regression without expert decisions, because the expert decisions in the 2008 assessment rendered the otherwise linear approaches non-linear despite the fact that the 2008 assessment used only linear methods. The F1 scores for all approaches appear low (F1 score < 0.10), do not improve with increasing model complexity, and, therefore, indicate the fundamental limitations of the input features ( i.e., training data). Until improved feature data are incorporated into the assessment process, simple non-linear algorithms ( e.g., XGBoost) perform equally well or better than more complex methods ( e.g., artificial neural networks) and remain easier to interpret.

Geothermics↗

USGS2004

Evidence for increased latent heat transport during the Cretaceous (Albian) greenhouse warming

Quantitative estimates of increased heat transfer by atmospheric H 2O vapor during the Albian greenhouse warming suggest that the intensified hydrologic cycle played a greater role in warming high latitudes than at present and thus represents a viable alternative to oceanic heat transport. Sphaerosiderite ??18O values in paleosols of the North American Cretaceous Western Interior Basin are a proxy for meteoric ??18O values, and mass-balance modeling results suggest that Albian precipitation rates exceeded modern rates at both mid and high latitudes. Comparison of modeled Albian and modern precipitation minus evaporation values suggests amplification of the Albian moisture deficit in the tropics and moisture surplus in the mid to high latitudes. The tropical moisture deficit represents an average heat loss of ???75 W/m2 at 10??N paleolatitude (at present, 21 W/m2). The increased precipitation at higher latitudes implies an average heat gain of ???83 W/m2 at 45??N (at present, 23 W/m2) and of 19 W/m2 at 75??N (at present, 4 W/m2). These estimates of increased poleward heat transfer by H2O vapor during the Albian may help to explain the reduced equator-to-pole temperature gradients. ?? 2004 Geological Society of America.

Geology↗

USGS2020

Using multiple environmental proxies and hydrodynamic modeling to investigate Late Holocene climate and coastal change within a large Gulf of Mexico estuarine system (Mobile Bay, Alabama, USA)

A high degree of uncertainty exists for understanding and predicting coastal estuarine response to changing climate, land-use, and sea-level conditions, leaving geologic records as a best-proxy for constraining potential outcomes. With the majority of the world's population focused in coastal regions, understanding how local systems respond to global, regional, and even local pressures is key in developing mitigation, adaptation, and management plans. The geomorphology of Mobile Bay in southeast Alabama (USA) has evolved considerably (e.g., bayhead delta back-stepping) over the late Holocene in response to global and regional sea-level and climate change. Smaller-scale geomorphic changes (e.g., spit and beach ridge development) have also had a significant influence on the evolution of the estuary. Organic matter characteristics, inorganic sediment geochemistry, benthic microfossils, and pollen in a ~ 3500 cal yr BP sediment sequence recovered in a gravity core (20GC) from Bon Secour Bay, a small sub-bay in the southeast corner of Mobile Bay, record time-varying marine influence. Increases in marine influence during ~3500 to 2300 cal yr BP and 1930 to 1160 cal yr BP are defined as zones with high-density and pre-dominantly calcareous foraminiferal species, abundant sand (>10%) and more marine-like geochemical signatures, which contrast the low-density and pre-dominantly agglutinated foraminiferal and more terrestrially influenced estuarine muds observed in other intervals of the sedimentary record (2300–1930 and 1160–400 cal yr BP) and the modern bay. Hydrodynamic models constrained by geomorphic boundary conditions for the time ~ 3500 cal yr BP, consistent with the most prominent marine-influenced sediment, provide insight to potential coastal configuration that might have permitted such marine water intrusion into the bay. Of several scenarios evaluated, a breach in Morgan Peninsula produces tidal circulation within the basin supportive of persistent marine incursions in the bay between ~3500 to 2300 cal yr BP. The findings show that slight variations in coastal configuration can have broad-scale effects on bays and estuaries with consequences that may relate to water quality, vertebrate and invertebrate habitat, and coastal vulnerability to episodic events like (extra)tropical storms.

Alabama, Mississippi↗

USGS2021

Testing hypotheses on signatures of precipitation variability in the river and floodplain deposits of the Paleogene San Juan Basin, New Mexico, USA

Much progress has been made in recent years towards a set of recognition criteria for river discharge variability in river channel deposits, and thus sedimentary proxies for precipitation variability. Despite this progress, there is currently no consensus on how different styles of discharge variability are reflected in river sedimentary records, and whether variable-discharge river records from different climate types can be distinguished. Herein, river discharge and precipitation variability in the Paleogene is investigated using associations between river channel and floodplain deposits across the Paleocene-Eocene boundary from the Paleocene upper Nacimiento Formation and the early Eocene San Jose Formation in the San Juan Basin, New Mexico, USA. The succession is identified as deposits of variable-discharge river systems based on shared channel-deposit characteristics with modern and ancient variable-discharge river systems and the proposed facies models, in addition to alternations of poorly drained and well-drained floodplain deposits and/or slickensides indicating alternating wet-dry cycles. A long-term stratigraphic trend toward increasingly well-drained floodplain deposits is also observed and hypothesized to indicate successively more arid conditions from the Paleocene into the early Eocene. Comparisons with modern rivers from various climate zones suggest a long-term shift from a monsoonal climate in the Paleocene, to a fluctuating subhumid climate, ultimately leading to semiarid to arid conditions in the early Eocene. These observations suggest that floodplain deposits may be a better indicator of ambient climate, whereas channel deposits are records for frequency and magnitude of high-intensity precipitation events. Therefore, the existing facies models for variable-discharge rivers that consider only channel facies may not capture critical information needed to make accurate interpretations of paleoclimatic conditions. This study also adds to a growing body of evidence from geologic records of mid-latitude Paleogene river systems suggesting increases in the magnitude or variability of river discharge coinciding with established climate perturbations.

New Mexico↗

USGS2004

The world's largest floods, past and present: Their causes and magnitudes

Floods are among the most powerful forces on earth. Human societies worldwide have lived and died with floods from the very beginning, spawning a prominent role for floods within legends, religions, and history. Inspired by such accounts, geologists, hydrologists, and historians have studied the role of floods on humanity and its supporting ecosystems, resulting in new appreciation for the many-faceted role of floods in shaping our world. Part of this appreciation stems from ongoing analysis of long-term streamflow measurements, such as those recorded by the U.S. Geological Survey's (USGS) streamflow gaging network. But the recognition of the important role of flooding in shaping our cultural and physical landscape also owes to increased understanding of the variety of mechanisms that cause floods and how the types and magnitudes of floods can vary with time and space. The USGS has contributed to this understanding through more than a century of diverse research activities on many aspects of floods, including their causes, effects, and hazards. This Circular summarizes a facet of this research by describing the causes and magnitudes of the world's largest floods, including those measured and described by modern methods in historic times, as well as floods of prehistoric times, for which the only records are those left by the floods themselves.

Circular↗

USGS1973

Species diversity: Patterns in modern and Miocene foraminifera of the eastern margin of North America

Patterns of foraminiferal species diversity were examined along the eastern margin of North America by utilizing the number of species, S, the information function, H(S), and species equitability, E. The 350 modern samples we studied extended from the Arctic to the Gulf of Mexico at depths ranging from a few meters to more than 5,000 m. In addition, 29 samples from Miocene strata of the Atlantic Coastal Plain and continental shelf were studied. Modern species diversity as measured by S and H(S) generally increases as depth increases and latitude decreases. Some notable exceptions occur, however, which are difficult to explain. For example, species diversity in the Arctic depth interval of 0 to 100 m is as high or higher than that found immediately south of Nova Scotia, in the Gulf of Maine, on Browns and Georges Banks, and even off the Gulf of Mexico deltas. At the moderate depth interval of 100 to 1,000 m, however, the entire margin north of Browns and Georges Banks has lower diversities than that to the south. The highest diversity by far in this depth interval occurs in the northeastern Gulf of Mexico. At the depth interval greater than 1,000 m, the more southern areas studied generally have a higher species diversity than the more northern Cape Cod to Maryland area. An exception to this is the northwestern Gulf of Mexico; this area is also an exception in that species diversity is significantly lower in the deeper waters than in the shallower waters in the same area. The measure of species equitability, E, showed no clear pattern with depth or latitude. This may be so because no simple pattern of species proportions exists or because the sampling was inadequate to measure it. Samples from the Miocene strata show a striking resemblance in species diversity to modern samples at similar depths and latitudes. Our observations indicate that species diversity and equitability have not increased during the last 15 × 10 6 yrs. The fossil and modern data indicate that each environment has its own carrying capacity and that this capacity is reached rather quickly. Although time and environmental stability are undoubtedly important in determining species diversity, as presently defined they are inadequate to explain all observed patterns. Long-term observations in various environments will be required to determine the relative importance of variables that affect species diversity.

Geological Society of America Bulletin↗

USGS1959

Ground-water provinces of India

This paper gives a general resume of ground-water utilization and development and describes the occurrence of water in eight ground-water provinces of India. The paper is based in part on observations of the writer during 1951-55 and in part on earlier work of the Geological Survey of India. Ground water has been utilized extensively in India since before the beginning of the Christian era. Currently (1956) ground water is an important source of supply for domestic, stock, municipal, and industrial needs throughout the Republic and is widely used for irrigation in the Peninsular and Ganges-Brahmaputra regions west of longitude 85°. Dug, bored, and drilled wells are the principal means by which ground water is developed, although locally infiltration tunnels or improved springs are used. Methods of lifting or pumping water from wells include the hand line and bucket, the hand-lift pump, the counterpoised sweep, bullocks, and "mote," the water wheel, horizontal and vertical centrifugal pumps, and deep-well turbine pumps. The most common device for lifting water for irrigation is still the time-honored bullock and "mote" (leather bag). However, in modern India there is increasing use of mechanical pumps. With respect to the occurrence of ground water, India can be divided into eight provinces, lying in three major regions, (1) the Peninsular region, (2) the Ganges-Brahmaputra region, and (3) the Himalayan region. The Peninsular region contains six ground-water provinces. Precambrian igneous, metamorphic, and indurated sedimentary rocks and early Tertiary volcanic rocks in three of these provinces yield many small supplies of water, which generally is of good quality but locally is brackish or salty. Cretaceous water-bearing sandstones in another province are moderately productive and in places are developed for large water supplies. Late Tertiary and Quaternary water-bearing sands and gravels in two other provinces sustain many small water supplies and several large water supplies-particularly in the coastal areas of southern India. The Ganges-Brahmaputra region is a single ground-water province in which many tens of thousands of small water supplies and several thousand large supplies are obtained from water-bearing sands and gravels in late Tertiary and Quaternary alluvium. This province constitutes a vast groundwater reservoir, which is the most productive in India. The Himalayan region also is considered as a single province, in which ground water occurs in a series of narrow valleys filled with moderately to highly permeable Quaternary alluvium. These alluvial valleys transmit large quantities of water to the ground-water reservoir in the Ganges-Brahmaputra region.

Economic Geology↗

USGS1986

Depletion of 13C in Cretaceous marine organic matter: Source, diagenetic, or environmental sigal?

Geochemical studies of Cretaceous strata rich in organic carbon (OC) from Deep Sea Drilling Project (DSDP) sites and several land sections reveal several consistent relationships among amount of OC, hydrocarbon generating potential of kerogen (measured by pyrolysis as the hydrogen index, HI), and the isotopic composition of the OC. First, there is a positive correlation between HI and OC in strata that contain more than about 1% OC. Second, percent OC and HI often are negatively correlated with carbon isotopic composition (σ 13 C) of kerogen. The relationship between HI and OC indicates that as the amount of organic matter increases, this organic matter tends to be more lipid rich reflecting the marine source of the organic matter. Cretaceous samples that contain predominantly marine organic matter tend to be isotopically lighter than those that contain predominantly terrestrial organic matter. Average σ 13 C values for organic matter from most Cretaceous sites are between −26 and −28‰, and values heavier than about −25‰ occur at very few sites. Most of the σ 13 C values of Miocene to Holocene OC-rich strata and modern marine plankton are between −16 to −23‰. Values of σ 13 C of modern terrestrial organic matter are mostly between −23 and −33‰. The depletion of terrestial OC in 13 C relative to marine planktonic OC is the basis for numerous statements in the literature that isotopically light Cretaceous organic matter is of terrestrial origin, even though other organic geochemical and(or) optical indicators show that the organic matter is mainly of marine origin. A difference of about 5‰ in σ 13 C between modern and Cretaceous OC-rich marine strata suggests either that Cretaceous marine planktonic organic matter had the same isotopic signature as modern marine plankton and that signature has been changed by diagenesis, or that OC derived from Cretaceous marine plankton was isotopically lighter by about 5‰ relative to modern plankton OC. Diagenesis does not produce a significant shift in σ 13 C in Miocene to Holocene sediments, and therefore probably did not produce the isotopically light Cretaceous OC. This means that Cretaceous marine plankton must have had σ 13 C values that were about 5‰ lighter than modern marine plankton, and at least several per mil lighter than Cretaceous terrestrial vegetation. The reason for these lighter values, however, is not obvious. It has been proposed that concentrations of CO 2 were higher during the middle Cretaceous, and this more available CO 2 may be responsible for the lighter σ 13 C values of Cretaceous marine organic matter.

Marine Geology↗

USGS2009

Dune mobility and aridity at the desert margin of northern China at a time of peak monsoon strength

Wind-blown sands were mobile at many sites along the desert margin in northern China during the early Holocene (11.5-8 ka ago), based on extensive new numerical dating. This mobility implies low effective moisture at the desert margin, in contrast to growing evidence for greater than modern monsoon precipitation at the same time in central and southern China. Dry conditions in the early Holocene at the desert margin can be explained through a dynamic link between enhanced diabatic heating in the core region of the strengthened monsoon and increased subsidence in drylands to the north, combined with high evapotranspiration rates due to high summer temperatures. After 8 ka ago, as the monsoon weakened and lower temperatures reduced evapotranspiration, eolian sands were stabilized by vegetation. Aridity and dune mobility at the desert margin and a strengthened monsoon can both be explained as responses to high summer insolation in the early Holocene. ?? 2009 Geological Society of America.

Geology↗