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At least 541 records · Page 30Linked to original sources
USGS2024

Timing and source of recharge to the Columbia River Basalt groundwater system in northeastern Oregon

Recharge to and flow within the Columbia River Basalt Group (CRBG) groundwater flow system of northeastern Oregon were characterized using isotopic, gas, and age-tracer samples from wells completed in basalt, springs, and stream base flow. Most groundwater samples were late-Pleistocene to early-Holocene; median age of well samples was 11,100 years. The relation between mean groundwater age and completed well depth across the eastern portion of the study area was similar despite differences in precipitation, topographic position, incision, thickness of the sedimentary overburden, and CRBG geologic unit. However, the lateral continuity in groundwater age was disrupted across large regional fault zones indicating these structures are substantial impediments to groundwater flow from the high-precipitation uplands to adjacent lower-precipitation and lower-elevation portions of the study area. Recharge rates calculated from the age-depth relations were <3 mm/yr and independent of the modern precipitation gradient across the study area. The age-constrained recharge rates to the CRBG groundwater system are considerably smaller than previously published estimates and highlight the uncertainty of prevailing models used to estimate recharge to the CRBG groundwater system across the Columbia Plateau in Oregon and Washington. Age tracer and isotopic evidence indicate recharge to the CRBG groundwater system is an exceedingly slow and localized process.

Oregon↗
USGS2006

Salinity and temperature tolerance experiments on selected Florida Bay mollusks

The ultimate goal of the Comprehensive Everglades Restoration Plan (CERP) is to restore and preserve the unique ecosystems of South Florida, including the estuaries. Understanding the effect of salinity and temperature changes, beyond typical oscillations, on the biota of South Florida's estuaries is a necessary component of achieving the goal of restoring the estuaries. The U.S. Geological Survey has been actively involved in researching the history of the South Florida Ecosystem, to provide targets, performance measures, and baseline data for restoration managers. These experiments addressed two aspects of ecosystem history research: 1) determining the utility of using molluscan shells as recorders of change in water chemistry parameters, primarily salinity, and 2) enhancing our in situ observations on modern assemblages by exceeding typically observed aquatic conditions. This set of experiments expanded our understanding of the effects of salinity, temperature and other water chemistry parameters on the reproduction, growth and overall survivability of key species of mollusks used in interpreting sediment core data. Observations on mollusks, plants and microbes made as part of these experiments have further refined our knowledge and understanding of the effects of ecosystem feedback and the role salinity and temperature play in ecosystem stability. The results have demonstrated the viability of several molluscan species as indicators of atypical salinity, and possibly temperature, modulations. For example Cerithium muscarum and Bulla striata demonstrated an ability to withstand a broad salinity and temperature range, with reproduction occurring in atypically high salinities and temperatures. These experiments also provided calibration data for the shell biogeochemistry of Chione cancellata and the possible use of this species as a water chemistry recorder. Observations made in the mesocosms, on a scale not normally observable in the field, have led to new questions about the influence of salinity on the localized ecosystem. The next phase of these experiments; to calibrate growth rate and reproductive viability in atypical salinities is currently underway.

Florida↗
USGS1985

Water resources of north-central Iowa

One of man's fundamental needs is water. Modern man needs both a safe and dependable supply of water to maintain his present economic, industrial, and cultural level. In order to use this natural resource in the most efficient and beneficial manner, a basic knowledge and understanding of water sources, and of the occurrence and potential of each source, needs to be gained. To provide this information, the U.S. Geological Survey, in cooperation with the Iowa Geological Survey, has compiled this atlas. It describes the water resources available for development in an 11-county area in north-central Iowa. The report contains information on the quantity, quality, and use of water from all known sources of water. This information is presented to aid water users and developers who are searching for and evaluating sources of water for specific sites. It also will be an aid to water planners and managers who must develop the available water resources on a regional basis.

Iowa↗
USGS1973

Stable isotope and chemical relations during mineralization in the Bodie mining district, Mono County, California

Stable isotope and chemical relations have been determined in a typical epithermal Au-Ag deposit located in the Bodie mining district of California. Analyses were made of altered host rocks, vein minerals, alteration clays, fluid inclusions, modern spring waters, and unaltered rocks of the area.The results indicate that a hydrothermal convection system was set up by the interaction of a cooling shallow intrusion and local meteoric water. The water traveled to depth where it picked up ore constituents and SiO 2 , K, and Rb, without significant shifts in the stable isotope ratios of the water. The altered rocks have equilibrated to various degrees with an ore fluid of constant K/Rb, O 18 /O 16 and D/H ratios. Deposition of ore took place over the approximate temperature range 215 degrees -245 degrees . From C 13 /C 12 ratios of minor calcite, a volcanic source of CO 2 is postulated. The chemical and isotope composition of the ore fluid is strikingly similar to that of modern spring waters in the area.All ore deposition at Bodie took place from essentially isotopically unaltered ground water with delta O 18 = -13ppm and delta D = -98ppm.

California↗
USGS1975

Modern pollen surface samples: An analysis of subsamples

Multiple subsamples of pollen samples obtained from the modern soil surface at two sites in southern Arizona were individually collected and analyzed to evaluate the practice of mixing subsamples when collecting modern surface samples. Results suggest that at least five subsamples must be mixed in order to avoid collecting a sample that is not representative of the local pollen rain.

Journal of Research of the U.S. Geological Survey↗
USGS2017

Modern landscape processes affecting archaeological sites along the Colorado River corridor downstream of Glen Canyon Dam, Glen Canyon National Recreation Area, Arizona

The landscape of the Colorado River through Glen Canyon National Recreation Area formed over many thousands of years and was modified substantially after the completion of Glen Canyon Dam in 1963. Changes to river flow, sediment supply, channel base level, lateral extent of sedimentary terraces, and vegetation in the post-dam era have modified the river-corridor landscape and have altered the effects of geologic processes that continue to shape the landscape and its cultural resources. The Glen Canyon reach of the Colorado River downstream of Glen Canyon Dam hosts many archaeological sites that are prone to erosion in this changing landscape. This study uses field evaluations from 2016 and aerial photographs from 1952, 1973, 1984, and 1996 to characterize changes in potential windblown sand supply and drainage configuration that have occurred over more than six decades at 54 archaeological sites in Glen Canyon and uppermost Marble Canyon. To assess landscape change at these sites, we use two complementary geomorphic classification systems. The first evaluates the potential for aeolian (windblown) transport of river-derived sand from the active river channel to higher elevation archaeological sites. The second identifies whether rills, gullies, or arroyos (that is, overland drainages that erode the ground surface) exist at the archaeological sites as well as the geomorphic surface, and therefore the relative base level, to which those flow paths drain. Results of these assessments are intended to aid in the management of irreplaceable archaeological resources by the National Park Service and stakeholders of the Glen Canyon Dam Adaptive Management Program.

Arizona↗
USGS2012

Offshore sand-shoal development and evolution of Petit Bois Pass, Mississippi-Alabama Barrier Islands, Mississippi, USA

Assessment of recently collected geophysical and sediment-core data identifies an extensive shoal field located off Dauphin and Petit Bois Islands. The shoals are the product of Pleistocene fluvial deposition and Holocene marine-transgressive processes, and their position and orientation oblique to the modern shoreline has been stable over the past century. The underlying stratigraphy has also influenced the evolution of the barrier platform and inlets. Buried distributary channels bisect the platform, creating erosion hotspots that breach during intense and repeated storms. Inlet growth inhibits littoral transport, and over time, reduces the down-drift sand supply. These relations demonstrate the role of the antecedent geologic framework on morphologic evolution. This study is part of the USGS Northern Gulf of Mexico Ecosystem Change and Hazard Susceptibility Project and the USACE Mississippi Coastal Improvements Program. These projects produced a wealth of information regarding coastal geology, geomorphology, and physical resources; some of the initial results are presented here.

Alabama;Mississippi↗
USGS2026

Regression models for estimating suspended sediment concentrations and loads and comparison with acoustic surrogate model on the Snake River, Weiser, Idaho, 1977–2022

The U.S. Geological Survey, in cooperation with Idaho Power, developed streamflow- based regression models to estimate suspended sediment concentration (SSC) and loads on the Snake River at Weiser, Idaho site (U.S. Geological Survey streamgage 13269000; hereafter referred to as “Snake at Weiser site”). This site sits upstream from the dams and reservoirs of the Hells Canyon Complex and the Hells Canyon National Recreation Area, where large sandbars along the Snake River that provide recreation and riparian habitat and host archaeological resources have declined since 1973. Analyses of samples from historical (1977- 2003) and modern (2017- 22) periods show that SSC has decreased over time, with median concentrations declining from 50 milligrams per liter (mg/L) to 28 mg/L. Mann- Kendall trend tests confirm statistically significant declines in total SSC and the fine and sand fractions of suspended sediment through the full period of record. Regression models specific to each period outperformed models using the full dataset, suggesting changes in the sediment supply to this reach of the Snake River and highlighting the need for period- based approaches. Regression models for total SSC and fine sediment were more accurate than those for sand, which exhibited greater error and bias, likely reflecting a sand supply limited by upstream dams. The regression model for modern period total SSC and a previously developed acoustic surrogate model showed similar performance, indicating both methods are viable for estimating SSC and loads. These findings help to better quantify suspended sediment concentrations and loads upstream of the Hells Canyon Complex and provide resource managers with tools to better quantify sediment loads affecting reservoir storage and the maintenance of sandbars in the Hells Canyon National Recreation Area.

Idaho, Nevada, Oregon, Utah↗
USGS2010

Eruptions of Hawaiian volcanoes—Past, present, and future

Viewing an erupting volcano is a memorable experience, one that has inspired fear, superstition, worship, curiosity, and fascination since before the dawn of civilization. In modern times, volcanic phenomena have attracted intense scientific interest because they provide the key to understanding processes that have created and shaped more than 80 percent of the Earth’s surface. The active Hawaiian volcanoes have received special attention worldwide because of their frequent spectacular eruptions, which often can be viewed and studied with relative ease and safety. In January 1987, the U.S. Geological Survey Hawaiian Volcano Observatory (HVO), then located on the caldera rim of Kīlauea, celebrated its 75th anniversary. To honor this anniversary, the U.S. Geological Survey (USGS) published Professional Paper 1350 , a comprehensive summary of the many studies on Hawaiian volcanism by USGS and other scientists through the mid-1980s. Drawing from the wealth of data contained in that volume, the USGS also published in 1987 the original edition of this general-interest booklet, focusing on selected aspects of the eruptive history, style, and products of two of the State of Hawaii’s active volcanoes—Kīlauea and Mauna Loa. A second edition of the booklet was published in 2010 to commemorate the Centennial of HVO (which occurred in January 2012), summarizing abundant new information gained since the January 1983 onset of Kīlauea’s middle East Rift Zone eruption at Pu‘u‘ō‘ō and the March 2008 beginning of Kīlauea’s summit lava-lake activity within Halema‘uma‘u. In this third edition, we include highlights from Kīlauea’s subsequent activity, including the 2018 eruption in the lower East Rift Zone—the largest and most destructive in at least 200 years—and associated summit-collapse events, the eruptions at Kīlauea’s summit since 2018, and the 2022 eruption of Mauna Loa, which occurred after 38 years of quiescence. It also considers new data leading to an improved history of Kīlauea’s explosive activity in the recent geologic past. This general-interest booklet is a companion to the one on Mount St. Helens volcano (southwestern Washington) first published in 1984, revised in 1990. Together, these publications illustrate the contrast between the two main types of volcanoes: shield volcanoes, such as those in the State of Hawaii, which generally are nonexplosive to weakly explosive; and composite volcanoes, such as Mount St. Helens in the Cascade Range, which generally erupt explosively.

Hawaii↗
USGS2003

Preliminary metallogenic belt and mineral deposit maps for northeast Asia

The metallogenic belts and locations of major mineral deposits of Northeast Asia are portrayed on Sheets 1-4. Sheet 1 portrays the location of significant lode deposits and placer districts at a scale of 1:7,500,000. Sheets 2-4 portray the metallogenic belts of the region in a series of 12 time-slices from the Archean through the Quaternary at a scale of 1:15,000,000. For all four map sheets, a generalized geodynamics base map, derived from a more detailed map by Parfenov and others (2003), is used as an underlay for the metallogenic belt maps. This geodynamics map underlay permits depicts the major host geologic units and structures that host metallogenic belts. Four tables are included in this report. A hierarchial ranking of mineral deposit models is listed in Table 1. And summary features of lode deposits, placer districts, and metallogenic belts are described in Tables 2, 3, and 4, respectively. The metallogenic belts for Northeast Asia are synthesized, compiled, described, and interpreted with the use of modern concepts of plate tectonics, analysis of terranes and overlap assemblages, and synthesis of mineral deposit models. The data supporting the compilation are: (1) comprehensive descriptions of mineral deposits; (2) compilation and synthesis of a regional geodynamics map the region at 5 million scale with detailed explanations and cited references; and (3) compilation and synthesis of metallogenic belt maps at 15 million scale with detailed explanations and cited references. These studies are part of a major international collaborative study of the Mineral Resources, Metallogenesis, and Tectonics of Northeast Asia that is being conducted from 1997 through 2002 by geologists from earth science agencies and universities in Russia, Mongolia, Northeastern China, South Korea, Japan, and the USA. Companion studies and previous publications are: (1) a detailed geodynamics map of Northeast Asia (Parfenov and 2003); (2) a compilation of major mineral deposit models (Rodionov and Nokleberg, 2000; Rodionov and others, 2000; Obolenskiy and others, 2003); and (3) a database on significant metalliferous and selected nonmetalliferous lode deposits, and selected placer districts (Ariunbileg and others, 2003).

Open-File Report↗
USGS2016

Groundwater ages from the freshwater zone of the Edwards aquifer, Uvalde County, Texas—Insights into groundwater flow and recharge

Tritium–helium-3 groundwater ages of the Edwards aquifer in south-central Texas were determined as part of a long-term study of groundwater flow and recharge in the Edwards and Trinity aquifers. These ages help to define groundwater residence times and to provide constraints for calibration of groundwater flow models. A suite of 17 samples from public and private supply wells within Uvalde County were collected for active and noble gases, and for tritium–helium-3 analyses from the confined and unconfined parts of the Edwards aquifer. Samples were collected from monitoring wells at discrete depths in open boreholes as well as from integrated pumped well-head samples. The data indicate a fairly uniform groundwater flow system within an otherwise structurally complex geologic environment comprised of regionally and locally faulted rock units, igneous intrusions, and karst features within carbonate rocks. Apparent ages show moderate, downward average, linear velocities in the Uvalde area with increasing age to the east along a regional groundwater flow path. Though the apparent age data show a fairly consistent distribution across the study area, many apparent ages indicate mixing of both modern (less than 60 years) and premodern (greater than 60 years) waters. This mixing is most evident along the “bad water” line, an arbitrary delineation of 1,000 milligrams per liter dissolved solids that separates the freshwater zone of the Edwards aquifer from the downdip saline water zone. Mixing of modern and premodern waters also is indicated within the unconfined zone of the aquifer by high excess helium concentrations in young waters. Excess helium anomalies in the unconfined aquifer are consistent with possible subsurface discharge of premodern groundwater from the underlying Trinity aquifer into the younger groundwater of the Edwards aquifer.

Texas↗
USGS2012

A brief review of the construction aggregates market

The U.S. Geological Survey defines the construction aggregates industry as those companies that mine and process crushed stone and/or construction sand and gravel. Aggregates have been used from the earliest times of our civilization for a variety of purposes - construction being the major use. As construction aggregates, crushed stone and construction sand and gravel are the basic raw materials used to build the foundation for modern society. The widespread use of construction aggregates is the result of their general availability throughout the country and around the world along with their relatively low cost. Although construction aggregates have a low unit value, their widespread use makes them major contributors to, and indicators of, the economic well-being of the nation.

Stone, Sand & Gravel Review↗
USGS1978

Structural control of the Cumberland River and its ancestral channels at Flat Lick, Kentucky

Remnants of old alluvium on bedrock benches, as much as 76 in (250 ft) above the present course of the Cumberland River near Flat Lick, Ky., are associated with meander scars and broad valleys now occupied by underflt streams. The distribution of old alluvium and associated topographic features define two ancestral channels of the Cumberland River. The ancestral channels and the present river channel are superimposed on the crest and flanks of the Flat Lick anticline. All three channels trend westward, roughly parallel to the axis of the anticline. The oldest channel is on the north flank, the second oldest channel is superimposed on the crest, and the modern channel is entrenched in the south-dipping limb of the fold. The sequential pattern of channel downcutting and migration across the crest of the anticline can be explained in terms of structural and lithologic constraints upon fluvial processes without recourse to contemporaneous tectonism. The Flat Lick area apparently has not experienced major deformation during the erosional history interpreted from the surficial geology. Direct evidence for the age of the old alluvium has not been found. However, an estimate based on erosion rates suggests that the ancestral channels could have been established and abandoned as recently as one-half million years ago.

Kentucky↗
USGS1966

Geologic effects of the March 1964 earthquake and associated seismic sea waves on Kodiak and nearby islands, Alaska

Kodiak Island and the nearby islands constitute a mountainous landmass with an aggregate area of 4,900 square miles that lies at the western border of the Gulf of Alaska and from 20 to 40 miles off the Alaskan mainland. Igneous and metamorphic rocks underlie most of the area except for a narrow belt of moderately to poorly indurated rocks bordering the Gulf of Alaska coast and local accumulations of unconsolidated alluvial and marine deposits along the streams and coast. The area is relatively undeveloped and is sparsely inhabited. About 4,800 of the 5,700 permanent residents in the area live in the city of Kodiak or at the Kodiak Naval Station. The great earthquake, which occurred on March 27, 1964, at 5:36 p.m. Alaska standard time (March 28,1964, 0336 Greenwich mean time), and had a Richter magnitude of 8.4-8.5, was the most severe earthquake felt on Kodiak Island and its nearby islands in modern times. Although the epicenter lies in Prince William Sound 250 miles northeast of Kodiak—the principal city of the area—the areal distribution of the thousands of aftershocks that followed it, the local tectonic deformation, and the estimated source area of the subsequent seismic sea wave, all suggest that the Kodiak group of islands lay immediately adjacent to, and northwest of, the focal region from which the elastic seismic energy was radiated. The duration of strong ground motion in the area was estimated at 2½ minutes. Locally, the tremors were preceded by sounds audible to the human ear and were reportedly accompanied in several places by visible ground waves. Intensity and felt duration of the shocks during the main earthquake and aftershock sequence varied markedly within the area and were strongly influenced by the local geologic environment. Estimated Mercalli intensities in most areas underlain by unconsolidated Quaternary deposits ranged from VIII to as high as IX. In contrast, intensities in areas of upper Tertiary rock ranged from VII to VIII, and in areas of relatively well indurated lower Tertiary and Mesozoic rocks, from VI to VII. Local subsidence of as much as 10 feet was widespread in noncohesive granular deposits through compaction, flow, and sliding that resulted from vibratory loading during the earthquake. This phenomenon, which was largely restricted to saturated beach and alluvial deposits or artificial fill, was locally accompanied by extensive cracking of the ground and attendant ejection of water and water-sediment mixtures. Numerous landslides, including a wide variety of rockfalls, rockslides, and flows along steep slopes, were triggered by the long-duration horizontal and vertical accelerations during the earthquake. The landslides are most numerous in a narrow belt along the southeast coast of Kodiak Island and the nearby offshore islands. Their abundance appears to be related to an area underlain predominantly by Tertiary rocks. Temporary and permanent changes of level occurred after the earthquake in some wells, lakes, and streams throughout the area; ice was cracked, and the salinity of a few wells increased. Permanent change of water level at some localities appears to be related to readjustments of fracture porosity by earthquake-induced movements of bedrock blocks. Increased salinity of wells in coastal areas resulted from encroachment of seawater into aquifiers after subsidence during the earthquake, and to flooding of watersheds by seismic sea waves. Vertical displacements, both downward and upward, occurred throughout the area as a result of crustal warping along a northeast-trending axis. Most of Kodiak and all of Afognak, Shuyak, and adjacent islands are within a regional zone of subsidence whose trough plunges gently northeastward and approximately coincides with the mountainous backbone of Kodiak Island. Subsidence in excess of 6 feet occurred throughout the northern part of the zone-a maximum subsidence of 6½ feet having occurred on Marmot and, eastern Afognak Islands. Southeast of the axis of tectonic tilting, uplift of at least 2lh feet occurred in a narrow zone that includes most of the southeasterly capes of Kodiak Island, the southeastern half of Sitkalidak Island, and Sitkinak Island. The uplift is inferred to extend offshore over much or all of the continental shelf adjacent to the Kodiak group of islands. Within the affected area, tectonic subsidence, which was locally augmented by surficial subsidence of unconsolidated. deposits, caused widespread inundation of shorelines and attendant damage to intertidal organisms, nearshore terrestrial vegetation, and salmon-spawning areas. The most devastating effect of the earthquake on Kodiak Island and nearby islands resulted from seismic sea waves that probably originated along a linear zone of differential uplift in the Gulf of Alaska. A train of at least seven seismic sea waves, having initial periods of 50–55 minutes, struck along all the southeast coast of the island group from 38 to 63 minutes after the earthquake. The southeast shores were repeatedly washed by destructive waves having runup heights along exposed coasts of perhaps as much as 40 feet above existing tide level, and of 8–20 feet along protected shores. Runup heights of the waves were much less on the northwest and southwest sides of the islands, and no wave damage was incurred there. Locally, high-velocity currents that accompanied the waves caused intense erosion and redistribution of unconsolidated natural and artificial shore deposits and of shallow sea-floor deposits. The Alaska earthquake was the greatest natural catastrophe to befall the Kodiak Island area in historic time. The combination of seismic shock and the earthquake-related tectonic deformation and seismic sea waves took 18 lives, destroyed property worth about $45 million, and resulted in estimated losses of income to the fishing industry of an additional $5 million. Most of the damage and all of the loss of life were directly attributable to the seismic sea waves that crippled the city of Kodiak, wiped out the village of Kaguyak, and destroyed most of the village of Old Harbor and parts of the villages of Afognak and Uzinki. Bridges and segments of the highways in the vicinity of the city of Kodiak were washed out, and parts of the Kodiak Naval Station were inundated and damaged. Especially serious to all the damaged communities was the loss of fishing boats, seafood processing plants, and other waterfront installations, which had been the mainstay of the economy. Additional heavy losses resulted from the combined regional tectonic and local surficial subsidence that occurred during the earthquake. Widespread shoreline flooding by high tides necessitated raising, protecting, or removing many installations otherwise undamaged by the earthquake or waves. Structural damage attributable to seismic shock during the earthquake was relatively light and was restricted to areas underlain by saturated unconsolidated deposits. The chief structural failure in the area as a result of shaking was the collapse of part of a cannery built on saturated beach deposits that were partially liquefied during the earthquake. Minor structural damage resulted from differential settlement and cracking of the ground on natural granular deposits and artificial fills. The overwhelming majority of structures are constructed on indurated bedrock; none of these sustained damage other than small losses resulting from shifting about and breakage of their contents.

Alaska↗
USGS2015

Measurement of in situ sulfur isotopes by laser ablation multi-collector ICPMS: opening Pandora’s Box

Laser ablation multi-collector ICPMS is a modern tool for in situ measurement of S isotopes. Advantages of the technique are speed of analysis and relatively minor matrix effects combined with spatial resolution sufficient for many applications. The main disadvantage is a more destructive sampling mechanism relative to the ion microprobe technique. Recent advances in instrumentation allow precise measurement with spatial resolutions down to 25 microns. We describe specific examples from economic geology where increased spatial resolution has greatly expanded insights into the sources and evolution of fluids that cause mineralization and illuminated genetic relations between individual deposits in single mineral districts.

Procedia Earth and Planetary Science↗
USGS1992

Effect of sea-level variation on upper-slope depositional processes offshore of Tiber delta, Tyrrhenian Sea, Italy

The upper slope and outer shelf in front of the Tiber River mouth (east-central Tyrrhenian Sea) exhibits a series of about 15 gullies that are not clearly related to present-day erosional or depositional processes. An extensive, high-resolution, seismic-reflection profiling survey of a 450 km 2 area in front of the Tiber delta shows several generations of similar features within the older depositional sequences underlying the outer continental shelf. The gully relief appears dominantly depositional, probably developed during lowstand periods when the Tiber River mouth was relatively near the shelf break. The position of the gullied intervals, including those on the modern slope relict from the last lowstand, shows a successive northward shift with time. This northward shift indicates continued tilting of this part of the eastern Tyrrhenian continental margin, probably resulting from a continued subsidence to the north.

Marine Geology↗
USGS2011

Mine wastes and human health

Historical mining and mineral processing have been linked definitively to health problems resulting from occupational and environmental exposures to mine wastes. Modern mining and processing methods, when properly designed and implemented, prevent or greatly reduce potential environmental health impacts. However, particularly in developing countries, there are examples of health problems linked to recent mining. In other cases, recent mining has been blamed for health problems but no clear links have been found. The types and abundances of potential toxicants in mine wastes are predictably influenced by the geologic characteristics of the deposit being mined. Hence, Earth scientists can help understand, anticipate, and mitigate potential health issues associated with mining and mineral processing.

Elements↗
USGS2005

The life cycle of a mineral deposit: a teacher's guide for hands-on mineral education activities

This teacher's guide defines what a mineral deposit is and how a mineral deposit is identified and measured, how the mineral resources are extracted, and how the mining site is reclaimed; how minerals and mineral resources are processed; and how we use mineral resources in our every day lives. Included are 10 activitybased learning exercises that educate students on basic geologic concepts; the processes of finding, identifying, and extracting the resources from a mineral deposit; and the uses of minerals. The guide is intended for K through 12 Earth science teachers and students and is designed to meet the National Science Content Standards as defined by the National Research Council (1996). To assist in the understanding of some of the geology and mineral terms, see the Glossary (appendix 1) and Minerals and Their Uses (appendix 2). The process of finding or exploring for a mineral deposit, extracting or mining the resource, recovering the resource, also known as beneficiation, and reclaiming the land mined can be described as the “life cycle” of a mineral deposit. The complete process is time consuming and expensive, requiring the use of modern technology and equipment, and may take many years to complete. Sometimes one entity or company completes the entire process from discovery to reclamation, but often it requires multiple groups with specialized experience working together. Mineral deposits are the source of many important commodities, such as copper and gold, used by our society, but it is important to realize that mineral deposits are a nonrenewable resource. Once mined, they are exhausted, and another source must be found. New mineral deposits are being continuously created by the Earth but may take millions of years to form. Mineral deposits differ from renewable resources, such as agricultural and timber products, which may be replenished within a few months to several years.

General Information Product↗