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At least 163 records · Page 9Linked to original sources

High-resolution airborne geophysical survey of the Shellmound, Mississippi area

In late February to early March 2018, the U.S. Geological Survey acquired 2,364 line-kilometers (km) of airborne electromagnetic, magnetic, and radiometric data in the Shellmound, Mississippi study area. The purpose of this survey is to contribute high-resolution information about subsurface geologic structure to inform groundwater models, water resource infrastructure studies, and local decision making. The Shellmound region hosts a managed aquifer recharge (MAR) pilot project, developed by the Agricultural Research Service of the U.S. Department of Agriculture. The MAR pilot project is investigating the use of bank filtration along the Tallahatchie River as a source for recharge in areas of significant groundwater decline. Direct injection into the Mississippi River Valley Alluvial aquifer (MRVA) occurs about 3 km from the extraction gallery. Understanding the structure of the aquifer, including both shallow and deep confining units, is important for the success of this pilot MAR study and may be even more important for potential future large-scale MAR projects and groundwater model development efforts.

Mississippi↗

Hydrogeology of the Cambrian-Ordovician aquifer system in the northern Midwest, United States with a section on ground-water quality

The Cambrian-Ordovician aquifer system contains the most extensive and continuous aquifers in the northern Midwest of the United States. It is the source of water for many municipalities, industries, and rural water users. Since the beginning of ground-water development from the aquifer system in the late 1800's, hydraulic heads have declined hundreds of feet in the heavily pumped Chicago-Milwaukee area and somewhat less in other metropolitan areas. The U.S. Geological Survey has completed a regional assessment of this aquifer system within a 161,000-square-mile area encompassing northern Illinois, northwestern Indiana, Iowa, southeastern Minnesota, northern Missouri, and Wisconsin. Consolidated sedimentary rocks in the northern Midwest range in age from Precambrian to Cretaceous and crop out in generally concentric, arcuate patterns, dipping away from structural highs (arches) on the Precambrian basement in northern Minnesota and Wisconsin toward structural lows (basins) to the south and east. The sedimentary bedrock is generally overlain by a veneer of glacial drift. Thickness of the sedimentary sequence increases to about 5,000 feet in the Forest City basin of southwestern Iowa and to about 14,000 and more than 15,000 feet in the Illinois and Michigan basins, respectively. Cambrian and Ordovician age rocks, mainly marine sandstone and carbonate rocks, compose much of the sedimentary sequence and form the Cambrian-Ordovician aquifer system. The aquifer system lies on the Precambrian basement, regarded as a regional confining unit. Six hydrogeologic units are defined; they are arranged as alternating pairs of an aquifer and an overlying confining. unit. The units are named using the predominant geologic nomenclature of the upper Mississippi Valley, which includes most of the study area. In the southern quarter of the area, the hydrogeologic units consist of equivalent formations of the Ozark area (mostly carbonate rocks). The uppermost part of the aquifer system is the Maquoketa confining unit, which consists of the Maquoketa Shale and the underlying dolomite and shale of the Galena Dolomite and the Decorah, Platteville, and Glenwood Formations. The underlying St. Peter-Prairie du Chien-Jordan aquifer is an important source of ground water in the western part of the area in Iowa and Minnesota, where the uniform Jordan Sandstone is hydraulically connected to overlying fractured dolomite of the Prairie du Chien Group. The unit is less important in the eastern part of Wisconsin and Illinois because the Jordan Sandstone is absent and the Prairie du Chien Group is thin or absent due to pre-St. Peter Sandstone erosion. Equivalent rocks in northern Missouri-the Roubidoux Formation and the Gasconade and Eminence Dolomites-are mainly carbonate rocks that are somewhat permeable and contain some sandstone. The St. Lawrence and Franconia Formations underlying the St. Peter-Prairie du Chien-Jordan aquifer consist generally of silty and shaly, fine-grained, poorly sorted, and dolomitic sandstones that restrict vertical movement of ground water and form a regional confining unit. In the southern and eastern parts of the area, the Potosi and Derby-Doerun Dolomites and the upper part of the Davis Formation are the equivalent rocks (mainly carbonate rocks). In the east-central part of the area in Illinois and Wisconsin, the Ironton-Galesville aquifer forms the most important aquifer of the Cambrian-Ordovician aquifer system, contributing about one-third of the yield from wells in the aquifer system in the Chicago area. The aquifer terminates to the west, south, and east, where the sandstones grade into less permeable carbonate rocks in central Iowa, central Illinois, and northwestern Indiana, respectively. The underlying Eau Claire Formation and its partial equivalent to the southwest, the Bonneterre Formation, form an important confining unit above the Mount Simon aquifer throughout much of the study area. Siltstone and shale are fairly common in the upper part of the Eau Claire Formation but less so in its northernmost extent in Wisconsin. Dolomite content increases southward and westward, where a middle dolomite facies grades laterally into the Bonneterre in Missouri, southwestern Minnesota, extreme south-central Wisconsin, and possibly in western Iowa. The basal unit in the Cambrian-Ordovician aquifer system, the Mount Simon aquifer, is present throughout the study area, except where it is absent over local highs of the Precambrian basement. It consists primarily of the Mount Simon Sandstone in the north and its equivalent in northern Missouri, the Lamotte Sandstone. The underlying Hinckley Sandstone of Precambrian age is included in Minnesota, as is the overlying Elmhurst Sandstone Member of the Eau Claire Formation in northern Illinois. The aquifer increases greatly in thickness and the water is progressively more saline away from the northern structural highs toward the basins. Much of the movement and discharge of ground water in the northern Midwest occurs in local, unconfined, shallow flow systems within a few miles of points of recharge. The rest of the water is semiconfined or confined in intermediate or regional flow systems within the bedrock, where flow is deeper, slower, and traverses much longer distances from recharge areas to discharge areas. The major areas of recharge to regional confined flow are in northwestern Iowa, southeastern Minnesota, western, southern, and eastern Wisconsin, and northern Illinois. Although the rate of flow is small, significant recharge to the Cambrian-Ordovician aquifer system also occurs as leakage through the Maquoketa confining unit, where the vertical hydraulic gradient is downward. Ground water in much of the confined aquifer system moves laterally from recharge areas toward the major river valleys and Lake Michigan or down dip toward the structural basins. The longest flow paths extend as much as 400 miles from northwestern Iowa southeast toward the Illinois basin or to the Mississippi River and Missouri River valleys near their confluence. Other major confined flow is from eastern Wisconsin toward the Michigan basin and southward flow from northeastern Illinois toward the Illinois basin. Regional ground-water discharge from the aquifer system is mainly diffuse upward leakage from confined aquifers along flow paths toward the structural basins. Very saline water around and brines within the basins restrict regional flow into the basins, forcing ground water to discharge upward. Water in intermediate flow systems discharges upward to the major river valleys. Original heads of more than 100 feet above land surface were recorded in the aquifer system near Lake Michigan in eastern Wisconsin and at Dubuque, Iowa, along the Mississippi River. The Cambrian-Ordovician aquifer system was developed rapidly in the late 1800's after the first deep well was drilled in Chicago in 1864. Many flowing wells were not controlled, which caused water levels in deep wells to decline, and many no longer flowed by the early 1900's. Heads in the aquifers have declined very little in most of the recharge or unconfined areas since ground-water withdrawal began, but major declines have occurred in confined areas. The largest declines in head are at Chicago, Illinois, Milwaukee and Green Bay, Wisconsin, and Mason City, Iowa, where the aquifer system is confined by the Maquoketa confining unit. The composite head in the aquifer system declined more than 900 feet in the deepest cones of depression in the Chicago area from 1864 to 1980 and about 375 feet in the cone at Milwaukee from 1880 to 1980. More than 200 feet of decline has occurred at Mason City. The head declined as much as 440 feet in Green Bay from 1886 to 1957, when the city discontinued use of its deep wells and began using water from Lake Michigan. The largest centers of pumping are in the Chicago and Twin Cities (Minneapolis-St. Paul, Minnesota) metropolitan areas about 180 million gallons per day each in 1980. Pumpage exceeded 10 million gallons per day in only a few other areas in 1980. Ground water in the Cambrian-Ordovician aquifer system in the northern Midwest is characterized by an extreme range of mineralization, but its quality in most of the area is good. The major cations are calcium, magnesium, and sodium, and the major anions are bicarbonate, sulfate, and chloride. Sodium, sulfate, and chloride distributions are closely related to the distribution pattern of dissolved solids but not in the same proportion. Dissolved-solids concentration is generally less than 1,000 milligrams per liter in the recharge areas of Wisconsin, southern Minnesota, northeastern Iowa, and north-central Illinois where the aquifer system crops out or subcrops beneath glacial drift. Ground water there is the Ca-Mg-HC03 type, derived from and identical to that in the overlying glacial drift. In northwestern Iowa and southwestern Minnesota, the water in both the glacial drift and the Cambrian-Ordovician aquifer system is a Ca-Na-S04HC03 type, derived from oxidation of pyrite in the overlying Cretaceous Dakota Formation. Transition to higher dissolved solids in the confined areas commonly is accompanied by increased sulfate concentration and· the occurrence of Ca-Na-S04-type water. Salinity of the ground water increases progressively toward the .basins, where dissolved solids exceed 200,000 milligrams per liter. Saline water is present in the Mount Simon aquifer near Lake Michigan in eastern Wisconsin and northeastern Illinois but occurs in successively younger rocks to the east and south as they dip toward the basins. Similarly, salinity increases down dip in Iowa to the southwest and south; however, regional ground-water flow in Iowa is from northwest to southeast. Much of the ground water in the confined aquifer system is isotopically depleted in 0180 and OD with respect to modern precipitation-an indication that the water originated as precipitation in a much colder climate than the present and probably was derived from recharge of glacial meltwater. On the basis of o34S values for sulfur in sulfate, it is believed that isostatic loading from glacial ice over the Michigan basin reversed the hydraulic gradient to trend westward, opposite from the present gradient, causing saline water in the Michigan basin to discharge westward through the present recharge areas. Natural water-quality problems in the Cambrian-Ordovician aquifer system are mainly the high dissolved-solids concentrations and associated high concentrations of sulfate and chloride, which limit the use of the water for municipal and domestic purposes in much of the confined aquifer system in central and southern Illinois, Indiana, southern and western Iowa, and northern Missouri. Another concern is that radium activity exceeds normal background concentrations of a few picocuries per liter in much of the confined aquifer system in eastern Wisconsin, northeastern Illinois, and central Iowa. Other common problems are high hardness and locally excessive concentrations of iron and hydrogen sulfide.

Iowa, Illinois, Indiana, Michigan, Minnesota, Miss↗

Preliminary report on an exploratory drill hole: New Madrid test well-1-X in Southeast Missouri

As part of the U.S. Geological Survey's investigation of earthquake hazards in the upper Mississippi embayment, a test well (NMTW-l-X) was drilled in the "bootheel" of Missouri, 21 km south-southwest of the town of New Madrid. The primary purpose of the well was to obtain in situ stress measurements from zones within subsurface Paleozoic rocks using the hydraulic fracturing (hydrofracture) technique. Such measurements determine the character and magnitude of the active tectonic stress field in an area and are helpful in evaluating the potential for faulting (Zoback and others, 1978). The new data about the active tectonic stress field can then be used to evaluate the various theories that have been proposed to explain the genesis and characteristics of the upper Mississippi embayment earthquakes. A second goal of the test well was to extensively study the post-Paleozoic stratigraphy in the area. Detailed stratigraphic information would provide a better understanding of the structural framework of the upper Mississippi embayment. Accurate knowledge of the stratigraphy would also help to identify the reflecting horizons that were recorded in a series of seismic reflection profiles that the U.S. Geological Survey had previously run throughout the upper Mississippi embayment. To strengthen the correlation between reflecting horizons and stratigraphic units, one of the reflection profiles was run within 10 m of the well. The stratigraphy and structure of the New Madrid, Mo., area are, at present, poorly understood. Only a handful of deep wells and test holes, some with only generalized driller's logs and few with accompanying geophysical logs, are available to aid in interpreting the subsurface geology of the upper Mississippi embayment. Extensive paleontologic and palynologic studies are planned to assist in identifying formal stratigraphic units and to help define the depositional history of the sediments. For the Tertiary and Cretaceous sequences, these investigations will also yield valuable biostratigraphic data by defining the biofacies changes that occur between the well-studied marine facies in the southern part and the time-equivalent, continental and nearshore-deltaic facies in the northern part of the embayment. This report was prepared to release preliminary data obtained during the drilling phase of the test well. It includes a short text describing mechanical operations and history of the drilling, some initial stratigraphic interpretations of the test-well data, and a brief discussion of studies generated by the project which are now in progress. Attached appendices contain a field driller's log and geophysical logs. In order to maintain consistency with standard drilling usage, measurements related to drilling operations are cited in English units.

Missouri↗

Archive of digital chirp subbottom profile data collected during USGS cruise 10BIM04 offshore Cat Island, Mississippi, September 2010

In September of 2010, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers (USACE), conducted a geophysical survey to investigate the geologic controls on barrier island framework of Cat Island, Miss., as part of a broader USGS study on Barrier Island Mapping (BIM). These surveys were funded through the Mississippi Coastal Improvements Program (MsCIP) and the Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazard Susceptibility Project as part of the Holocene Coastal Evolution of the Mississippi-Alabama Region Subtask. This report serves as an archive of unprocessed digital chirp subbottom data, trackline maps, navigation files, GIS files, Field Activity Collection System (FACS) logs, and formal FGDC metadata. Gained (showing a relative increase in signal amplitude) digital images of the seismic profiles are also provided. Refer to the Acronyms page for expansions of acronyms and abbreviations used in this report. The USGS Saint Petersburg Coastal and Marine Science Center (SPCMSC) assigns a unique identifier to each cruise or field activity. For example, 10BIM04 tells us the data were collected in 2010 during the fourth field activity for that project in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the field activity identification (ID). All chirp systems use a signal of continuously varying frequency; the EdgeTech SB-512i system used during this survey produces high-resolution, shallow-penetration (typically less than 50 milliseconds (ms)) profile images of sub-seafloor stratigraphy. The towfish contains a transducer that transmits and receives acoustic energy; it was housed within a float system (built at the SPCMSC), which allows the towfish to be towed at a constant depth of 1.07 meters (m) below the sea surface. As transmitted acoustic energy intersects density boundaries, such as the seafloor or sub-surface sediment layers, some energy is reflected back toward the transducer, received, and recorded by a Personal Computer (PC)-based seismic acquisition system. This process is repeated at regular time intervals (for example, 0.125 seconds (s)), and returned energy is recorded for a specific duration (for example, 50 ms). In this way, a two-dimensional (2-D) vertical image of the shallow geologic structure beneath the ship track is produced. Figure 1 displays the acquisition geometry. Refer to table 1 for a summary of acquisition parameters and table 2 for trackline statistics. The archived trace data are in standard Society of Exploration Geophysicists (SEG) SEG Y rev. 0 format (Barry and others, 1975); the first 3,200 bytes of the card image header are in American Standard Code for Information Interchange (ASCII) format instead of Extended Binary Coded Decimal Interchange Code (EBCDIC) format. The SEG Y files may be downloaded and processed with commercial or public domain software such as Seismic Unix (SU) (Cohen and Stockwell, 2010). See the How To Download SEG Y Data page for download instructions. The printable profiles provided here are GIF images that were processed and gained using SU software, and they can be viewed from the Profiles page or from links located on the trackline maps; refer to the Software page for links to example SU processing scripts. The SEG Y files are available on the DVD version of this report or on the Web, downloadable via the USGS Coastal and Marine Geoscience Data System (http://cmgds.marine.usgs.gov). The data are also available for viewing using GeoMapApp (http://www.geomapapp.org) and Virtual Ocean (http://www.virtualocean.org) multi-platform open source software.

Mississippi↗

Geologic and hydrologic summary of salt domes in Gulf Coast region of Texas, Louisiana, Mississippi, and Alabama

There are 263 known or suspected onshore salt domes in the Texas-Louisiana-Mississippi-Alabama portion of the Gulf Coast geosyncline. The top of the salt in 148 of them is probably deeper than desirable for a waste repository site, and 79 of those that are shallow enough are probably unavailable for a site because of present use by industry for gas storage or production of oil, salt, or sulfur. In this report we have compiled the available geologic and hydrologic background data pertinent to the evaluation of the remaining 36 known or suspected salt domes as potential sites for waste storage. There are three parts to this compilations: 1) summaries of the geology and hydrology of the salt-dome province as a whole; 2) summaries of the physiography, climate, geology, and hydrology of each of the five salt-dome basins that occur within the province; and 3) an appendix of background data for each of the 36 potentially acceptable domes. The distribution of salt domes in the province is genetically related to areas of relative subsidence that formed basins or depocenters within the Gulf Coast geosyncline. In some cases, as in northeast Texas and south Louisiana, the locations of individual domes or groups of domes are related to deep movement of salt along axial trends. The salt domes in the interior salt-dome subprovince are probably more structurally stable than those of the coastal subprovince because salt diapirism is inferred to have ceased around Miocene time in the interior but may still be active in parts of the coastal subprovince. Although the size and shape of many domes is unknown or can only be roughly approximated, each of the five basins in the province appears to contain potentially acceptable domes of adequate size for a repository. We recognize no pattern to the distribution of salt-dome size. Caprock thicknesses vary greatly within each salt-dome basin,and we recognize no pattern to the variations. Among the potentially acceptable domes, the depths to the top of the salt are generally greatest in the Mississippi salt-dome basin, where all tops are more than 1,500 feet deep. Intermediate depths of about 1,000 feet are common in the east Texas-south Louisiana salt-dome basin. Depths to salt tops in the north Louisiana and northeast Texas basins are variable but most are less than 1,000 feet. Available drilling records are generally adequate to determine the number of wells drilled on or in the vicinity of individual domes and also the well locations. The numbers of wells vary widely within each salt-dome basin. More salt domes are currently available for use as repository sites in the interior subprovince than in the coastal subprovince, where the pressure for industrial use of domes is high. In the interior subprovince many of the potentially acceptable domes are located beneath hilly well-drained terrain that is not subject to flooding or other surface-water problems. Although topographic depressions occupied by shallow lakes, swamps, or 'salines' occur over several of the domes, they are generally flanked by topographically high ground where surface facilities could be sited without complications.A few of the potentially acceptable domes are located beneath floodplains where surface facilities might face hazards from flooding. In the coastal subprovince several of the potentially acceptable domes are located in relatively flat poorly drained terrain where surface flooding might constitute a potential hazard. The availability of fresh to slightly saline ground water varies considerably within each salt-dome basin. We have outlined some of the factors that are responsible for the variations and have provided or referred to maps and geohydrologic cross sections that illustrate the general distribution of fresh to slightly saline water. The top of the salt in about half of the known potentially acceptable domes is below the regional base of the fresh to slightly saline ground-water system, but in a few of

Alabama, Louisiana, Mississippi, Texas↗

Trends and seasonal patterns of nitrogen and phosphorus concentrations and loads in two Mississippi Alluvial Plain watersheds following nutrient reduction efforts during 2010–22

The Mississippi Alluvial Plain ecoregion in Mississippi was historically part of the largest continuous wetland in North America but was clearcut and converted to row crop agriculture beginning in the late 1800s. To reduce the effects of agriculture on surface waters in the Mississippi Alluvial Plain, nutrient reduction best management practices have been implemented throughout the region, particularly in two small watersheds: Harris Bayou watershed (174.04 square kilometers) and Porter Bayou watershed (267.15 square kilometers). Since 2009, the U.S. Geological Survey, in cooperation with the Mississippi Department of Environmental Quality, has collected water-quality samples monthly and during high-flow runoff events, at three locations within each watershed to monitor and assess nutrient trends following best management practice implementation. Here, we have analyzed long-term and seasonal trends in discharge, total nitrogen (TN), and total phosphorus (TP) concentrations and loads using a combination of quantile-Kendall analysis, quantile regression, generalized additive models, and weighted regression on time, discharge, and season. In Harris Bayou watershed, discharge values at a ~0.4–0.5 daily nonexceedance probability increased by 15 percent per year at the uppermost monitoring site. Additionally, TN concentrations decreased throughout the watershed over time, particularly in the spring and winter months. Reductions in TP were less apparent and only observed at one sampling location in Harris Bayou watershed. Nutrient concentrations in Porter Bayou watershed remained consistent over time and increased at one sampling location. However, despite discrepancies in concentration trends, flow-normalized TN and TP loads consistently decreased over time in both watersheds. At the mouth of both watersheds, peak TN and TP loads decreased between 37.7 and 56.9 percent. Collectively, these results provide evidence that best management practices may help reduce the effect of agricultural practices in the region, particularly in Harris Bayou watershed. Additionally, management efforts resulted in greater reductions in TN concentrations than in TP concentrations.

Mississippi↗

Estimation of suspended sediment at a discontinued streamgage on the lower Minnesota River at Fort Snelling State Park, Minnesota

In the spring of 2019, ice sheets transported down-stream during a large streamflow rise event in the lower Minnesota River destroyed an index-velocity streamgage at the Minnesota River at Fort Snelling State Park, Minnesota (U.S. Geological Survey station 05330920; hereafter referred to as “Ft. Snelling”). The streamgage previously used an acoustic Doppler velocity meter to provide instantaneous streamflow and suspended-sedimentation concentration (SSC) data in backwater conditions caused by the confluence with the Mississippi River. In response, the U.S. Geological Survey cooperated with the U.S. Army Corps of Engineers and Lower Minnesota River Watershed District to develop linear regression models that estimate SSCs and suspended-sand concentrations (sand) at the destroyed streamgage using streamflow data from an upstream site Minnesota River near Jordan, Minn. (U.S. Geological Survey station 05330000, hereafter referred to as “Jordan”). Simple linear regression models were developed for selected positions on the streamflow hydrograph to estimate SSC and sand at Ft. Snelling from the streamflow at Jordan. Statistically significant models could not be developed for estimating SSC at low streamflows and sand at high streamflows. Models developed to estimate sand were more uncertain than models used to estimate SSC, and models using streamflow to predict SSC and sand were more uncertain than models using acoustic backscatter to predict SSC. Annual loads of SSC and sand estimated from these models show the dynamic nature of sediment transport and storage in this section of the lower Minnesota River. These models and the associated ancillary data can help with management decisions that are crucial in managing aquatic habitat, supporting power production, and commercial navigation.

Minnesota↗

Ground-water levels in the alluvial aquifer in eastern Arkansas, 1987

Groundwater level measurements of 516 wells that tap the alluvial aquifer in the Quaternary deposits of the Mississippi Alluvial Plain were made by U.S. Geological Survey and district Soil Conservation Service personnel during 1987. The shallowest prepumping water levels occurred in Ashley, Clay, Crittenden, Greene, Mississippi, Phillips, and Randolph Counties where water levels averaged less than 20 ft below the land surface. The deepest water levels occurred in Arkansas, Lonoke, Poinsett, and Prairie Counties where water levels of more than 100 ft below land surface were measured. Water levels in the postpumping season averaged about 3.3 ft lower than during the prepumping season. (USGS)

Open-File Report↗

U-Pb ages of detrital zircons from the Tertiary Mississippi River delta plain in central Louisiana: Insights into sediment provenance

The sources of the tremendous amount of Cenozoic siliciclastic sediment deposited in the Gulf of Mexico region remain debated because of a lack of definitive provenance-identifying characteristics. In an effort to build on prior provenance analysis, we present 101–160 single-grain detrital zircon U-Pb ages for each of 10 outcrop samples from Upper Paleocene to Upper Miocene sandstones from a ∼10,000 km2 swath of central Louisiana corresponding to the ancient Mississippi River Delta, the largest Cenozoic depocenter in the northern Gulf of Mexico region. Sample depositional age control is derived from biostratigraphy and/or regional lithostratigraphic correlation. U-Pb ages in each of the samples range from Cenozoic to Archean, and correspond to the ages of various geologic terranes that underlie the modern Mississippi River drainage basin. However, the prominence of various age distributions changes systematically through the Cenozoic stratigraphy, and pronounced shifts in the abundance of certain age distributions between stratal packages appear to be correlated to shifts in heavy mineral assemblages recorded across the northern Gulf of Mexico coastal plain. Comparison of coastal plain detrital zircon age distributions to age distributions from North American sedimentary cover and the ages of major North American crystalline basement rocks, aided by a sediment mixing model, illuminates the provenance of each of the stratal packages, and suggests that (1) the Mississippi River catchment has resembled its present configuration, at least in the east-west dimension, for much, if not all, of the Cenozoic, and (2) depositional episodes on the Louisiana coastal plain characterized by high sediment supply also corresponded to high proportions of sediment sourcing from the Sevier-Laramide region of the interior western United States. Sediment supply to the Louisiana coastal plain by the paleo–Mississippi River has generally been high during the Cenozoic, except for an anomalous low during the Middle Eocene, when the abundance of sediment derived from the Rocky Mountain region decreased dramatically relative to sediment derived from the Appalachian region.

Louisiana↗

A preliminary report of the geohydrology of the Mississippi salt-dome basin

The U.S. Department of Energy is investigating the suitability of salt domes in the Mississippi salt-dome basin as repositories for storing radioactive wastes. The Department of Energy has requested that the U.S. Geological Survey describe the groundwater hydrology of the Mississippi salt-dome basin, giving special attention to direction and rate of movement of water. In this first part of a continuing investigation the data obtained from one year of extensive literature search and data compilation are summarized. The regional groundwater hydrology in the salt-dome basin is defined with respect to (1) groundwater flow, (2) facies changes, (3) geological structure, (4) recharge and discharge, (5) freshwater-saltwater relations, and (6) identification of localities where additional data are needed. From the 50 piercement-type salt domes in the Mississippi salt-dome basin three domes (Richton, Cypress Creek, and Lampton) were selected for more intensive study. To further evaluate the geohydrology of Richton, Lampton, and Cypress Creek domes as possible sites for storage of radioactive waste, an intensive geohydrologic study based on a comprehensive test drilling program near the domes is planned. (USGS)

Mississippi↗

Proceedings of Conference XVIII: a workshop on "Continuing actions to reduce losses from earthquakes in the Mississippi Valley area," 24-26 May, 1982, St. Louis, Missouri

The U.S. Geological Survey and the Federal Emergency Management Agency sponsored a workshop on, "Continuing Actions to Reduce Losses from Earthquakes in the Mississippi Valley area," in St. Louis, Missouri, on May 24-26, 1982. Seventy individuals (see Appendix A) representing local, State, and Federal government; business and industry; and the research community participated in the three day workshop. Collectively, the participants had backgrounds in disaster preparedness, disaster response and recovery, geology, geophysics, seismology, engineering, architecture, social science, law, insurance, and land-use planning. Two-thirds of them came from the Mississippi Valley area about one half of these had also attended an earlier USGS-FEMA workshop held in Knoxville, Tennessee on September 16-18, 1981 (Hays, 1982). The St. Louis workshop is the 18th in the continuing series of conferences and workshops which the Geological Survey initiated in 1977 to improve the transfer and application of research results throughout the Nation. It is the second workshop to focus on dealing with the earthquake threat in the Eastern United States. The first one, "Preparing for and Responding to a Damaging Earthquake in the Eastern United States," was held in Knoxville, Tennessee, and emphasized the development of a draft 5-year plan to improve the state-of-earthquake-preparedness. The Knoxville workshop demonstrated that policymakers and members of the scientific-technical community can assimilate and synthesize a great deal of information and work together to devise practical plans. The St. Louis workshop, a sequel to the Knoxville workshop, identified those actions out of the range of possible actions which are most achievable; that is, the actions having the highest payoff and trre lowest cost and effort requirements. These action plans, which identify steps that can be undertaken immediately to reduce losses from earthquakes in each of the seven States in the Mississippi Valley area, are contained in this report. The draft 5-year plan for the Central United States, prepared in the Knoxville workshop, was the starting point of the small group discussions in the St. Louis workshop which lead to the action plans contained in this report. For completeness, the draft 5-year plan for the Central United States is reproduced as Appendix B.

Open-File Report↗

Correlation of the Tuscaloosa marine shale in Mississippi, Louisiana, and east Texas, U.S.A.

The U.S. Geological Survey (USGS) completed an assessment of undiscovered, technically recoverable unconventional petroleum resources in the Upper Cretaceous marine shale of the Tuscaloosa Group (Tuscaloosa marine shale; TMS) in 2018. As part of the geologic characterization in preparation for the assessment, a series of wireline log cross sections were constructed to illustrate TMS thickness trends and aid in the delineation of the assessment unit (AU). Lithostratigraphic units were correlated based on gamma ray, spontaneous potential, and resistivity log responses and generally follow the classic stratigraphic nomenclature first proposed in the 1960s. Correlated stratigraphic units include (from youngest to oldest) the Austin Group, Eagle Ford Shale, upper Tuscaloosa, Tuscaloosa marine shale, lower Tuscaloosa, and Lower Cretaceous. A high resistivity zone (HRZ) in the basal Tuscaloosa marine shale was delineated where resistivity was greater than 5 ohm-meters and high resistivity sections were separated by less than 20 feet of low resistivity shale. The HRZ was identified regionally and might indicate petroleum accumulations in the TMS. Third-party biostratigraphic data from wells in Mississippi and Louisiana were integrated into the well control, which aided wireline log correlation. Cross sections depict east-west thinning of the TMS onto the Sabine uplift and north-south thickening of the TMS off of the Lower Cretaceous shelf margin. The western boundary of the USGS-defined Tuscaloosa Marine Shale Continuous Oil AU was drawn in western Louisiana near the Texas-Louisiana state border based on stratigraphic thinning of the Upper Cretaceous section onto the structural high of the Sabine uplift as projected downdip.

Louisiana, Mississippi, Texas↗

Streamflow and nutrient fluxes of the Mississippi-Atchafalaya River Basin and subbasins for the period of record through 2005

U.S. Geological Survey has monitored streamflow and water quality systematically in the Mississippi-Atchafalaya River Basin (MARB) for more than five decades. This report provides streamflow and estimates of nutrient delivery (flux) to the Gulf of Mexico from both the Atchafalaya River and the main stem of the Mississippi River. This report provides streamflow and nutrient flux estimates for nine major subbasins of the Mississippi River. This report also provides streamflow and flux estimates for 21 selected subbasins of various sizes, hydrology, land use, and geographic location within the Basin. The information is provided at each station for the period for which sufficient water-quality data are available to make statistically based flux estimates (starting as early as water year1 1960 and going through water year 2005). Nutrient fluxes are estimated using the adjusted maximum likelihood estimate, a type of regression-model method; nutrient fluxes to the Gulf of Mexico also are estimated using the composite method. Regression models were calibrated using a 5-year moving calibration period; the model was used to estimate the last year of the calibration period. Nutrient flux estimates are provided for six water-quality constituents: dissolved nitrite plus nitrate, total organic nitrogen plus ammonia nitrogen (total Kjeldahl nitrogen), dissolved ammonia, total phosphorous, dissolved orthophosphate, and dissolved silica. Additionally, the contribution of streamflow and net nutrient flux for five large subbasins comprising the MARB were determined from streamflow and nutrient fluxes from seven of the aforementioned major subbasins. These five large subbasins are: 1. Lower Mississippi, 2. Upper Mississippi, 3. Ohio/Tennessee, 4. Missouri, and 5. Arkansas/Red.

Louisiana, Mississippi↗

Bed-Sediment Sampling and Analysis for Physical and Chemical Properties of the Lower Mississippi River near Memphis, Tennessee

In February 2010, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, Memphis District, investigated the presence of inorganic elements and organic compounds in bed sediments of the lower Mississippi River. Selected sites were located in the navigation channel near river miles 737, 773, and 790 near Memphis, Tennessee. Bed-sediment samples were collected using a Shipek grab sampler mounted to a boom crane with a motorized winch. Samples then were processed and shipped to the U.S. Geological Survey Sediment Laboratory in Rolla, Missouri, the USGS National Water Quality Laboratory in Denver, Colorado, and to TestAmerica Laboratory, Inc. in West Sacramento, California. Samples were analyzed for grain size, inorganic elements (including mercury), and organic compounds. Chemical results were tabulated and listed with sediment-quality guidelines and presented with the physical property results. All of the bed material samples collected during this investigation yielded concentrations that were less than the Consensus-Based Probable Effect Concentration guidelines. The physical properties were tabulated and listed using a standard U.S. Geological Survey scale of sizes by class for sediment analysis. All of the samples collected during this investigation indicated a percent composition mostly comprised of sand, ranging from less than 0.125 millimeters to less than 2 millimeters.

Open-File Report↗

A Review of Land-Cover Mapping Activities in Coastal Alabama and Mississippi

INTRODUCTION Land-use and land-cover (LULC) data provide important information for environmental management. Data pertaining to land-cover and land-management activities are a common requirement for spatial analyses, such as watershed modeling, climate change, and hazard assessment. In coastal areas, land development, storms, and shoreline modification amplify the need for frequent and detailed land-cover datasets. The northern Gulf of Mexico coastal area is no exception. The impact of severe storms, increases in urban area, dramatic changes in land cover, and loss of coastal-wetland habitat all indicate a vital need for reliable and comparable land-cover data. Four main attributes define a land-cover dataset: the date/time of data collection, the spatial resolution, the type of classification, and the source data. The source data are the foundation dataset used to generate LULC classification and are typically remotely sensed data, such as aerial photography or satellite imagery. These source data have a large influence on the final LULC data product, so much so that one can classify LULC datasets into two general groups: LULC data derived from aerial photography and LULC data derived from satellite imagery. The final LULC data can be converted from one format to another (for instance, vector LULC data can be converted into raster data for analysis purposes, and vice versa), but each subsequent dataset maintains the imprint of the source medium within its spatial accuracy and data features. The source data will also influence the spatial and temporal resolution, as well as the type of classification. The intended application of the LULC data typically defines the type of source data and methodology, with satellite imagery being selected for large landscapes (state-wide, national data products) and repeatability (environmental monitoring and change analysis). The coarse spatial scale and lack of refined land-use categories are typical drawbacks to satellite-based land-use classifications. Aerial photography is typically selected for smaller landscapes (watershed-basin scale), for greater definition of the land-use categories, and for increased spatial resolution. Disadvantages of using photography include time-consuming digitization, high costs for imagery collection, and lack of seasonal data. Recently, the availability of high-resolution satellite imagery has generated a new category of LULC data product. These new datasets have similar strengths to the aerial-photo-based LULC in that they possess the potential for refined definition of land-use categories and increased spatial resolution but also have the benefit of satellite-based classifications, such as repeatability for change analysis. LULC classification based on high-resolution satellite imagery is still in the early stages of development but merits greater attention because environmental-monitoring and landscape-modeling programs rely heavily on LULC data. This publication summarizes land-use and land-cover mapping activities for Alabama and Mississippi coastal areas within the U.S. Geological Survey (USGS) Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazard Susceptibility Project boundaries. Existing LULC datasets will be described, as well as imagery data sources and ancillary data that may provide ground-truth or satellite training data for a forthcoming land-cover classification. Finally, potential areas for a high-resolution land-cover classification in the Alabama-Mississippi region will be identified.

Open-File Report↗

Archive of side scan sonar and swath bathymetry data collected during USGS cruise 10CCT03 offshore of the Gulf Islands National Seashore, Mississippi, from East Ship Island, Mississippi, to Dauphin Island, Alabama, April 2010

In April of 2010, the U.S. Geological Survey (USGS) conducted a geophysical survey from the east end of East Ship Island, Miss., extending to the middle of Dauphin Island, Ala. (fig. 1). This survey had a dual purpose: (1) to interlink previously conducted nearshore geophysical surveys (shoreline to ~2 km) with those of offshore surveys (~2 to ~9 km) in the area, and (2) to extend the geophysical survey to include a portion of the Dauphin Island nearshore zone. The efforts were part of the USGS Gulf of Mexico Science Coordination partnership with the U.S. Army Corps of Engineers (USACE) to assist the Mississippi Coastal Improvements Program (MsCIP) and the Northern Gulf of Mexico (NGOM) Ecosystem Change and Hazards Susceptibility Project by mapping the shallow geological stratigraphic framework of the Mississippi Barrier Island Complex. These geophysical surveys will provide the data necessary for scientists to define, interpret, and provide baseline bathymetry and seafloor habitat for this area and to aid scientists in predicting future geomorpholocial changes of the islands with respect to climate change, storm impact, and sea-level rise. Furthermore, these data will provide information for barrier island restoration feasibility, particularly in Camille Cut, and efforts for the preservation of historical Fort Massachusetts. For more information refer to http://ngom.usgs.gov/gomsc/mscip/. This report serves as an archive of the processed multibeam bathymetry and side scan sonar (SSS) data. Data products herein include gridded and interpolated digital depth surfaces, seabed surface backscatter imagery, and x,y,z data products for both multibeam bathymetry and side scan sonar imagery. Additional files include trackline maps, navigation files, geograpahic information system (GIS) files, Field Activity Collection System (FACS) logs, and formal Federal Geographic Data Committee (FGDC) metadata. Scanned images of the handwritten FACS logs and digital FACS logs are also provided as PDF files. Refer to the Acronyms page for description of acronyms and abbreviations used in this report or hold the cursor over an acronym for a pop-up explanation. The USGS St. Petersburg Coastal and Marine Science Center assigns a unique identifier to each cruise or field activity. For example, 10CCT03 tells us the data were collected in 2010 for the Coastal Change and Transport (CCT) study and the data were collected during the third (03) field activity for that project in that calendar year. Refer to http://walrus.wr.usgs.gov/infobank/programs/html/definition/activity.html for a detailed description of the method used to assign the field activity ID. Data were collected aboard the U.S. Army Corps of Engineers (USACE) SV Irvington , a 56-foot (ft) Kvichak Marine Industries, Inc., catamaran (fig. 2). Side scan sonar and multibeam bathymetry data were collected simultaneously along the tracklines. The side scan sonar towfish was towed off the starboard side just slightly behind the vessel, close to the seafloor. The multibeam transducer was attached to a retractable strut-arm lowered between the catamaran hulls. Navigation was acquired with an Applanix POS MV and differentially corrected using the broadcast signal from a local National Geodetic Survey (NGS) Continuously Operating Reference Station (CORS) beacon. See the digital FACS equipment log for details about the acquisition equipment used. Raw datasets were stored digitally and processed using HYPACK Inc., HYSWEEP software at the USACE Mobile, Ala., District office. For more information on processing refer to the Equipment and Processing page. Chirp seismic data were also collected during this survey and are archived separately.

Gulf Islands National Seashore↗

Water Levels and Selected Water-Quality Conditions in the Mississippi River Valley Alluvial Aquifer in Eastern Arkansas, 2006

During the spring of 2006, the U.S. Geological Survey, in cooperation with the Arkansas Natural Resource Commission and the Arkansas Geological Survey, measured water levels in 707 wells completed in the Mississippi River Valley alluvial aquifer in eastern Arkansas. Ground-water levels are affected by ground-water withdrawals resulting in depressions. In 2006, the lowest water-level altitude was 76 feet above the National Geodetic Vertical Datum of 1929 in the center of Arkansas County. The highest water-level altitude was 289 feet above the National Geodetic Vertical Datum of 1929 in northeastern Clay County on the west side of Crowleys Ridge. Two large depressions in the potentiometric surface are located in Arkansas, Lonoke, and Prairie Counties and west of Crowleys Ridge in Craighead, Cross, Lee, Monroe, Poinsett, St. Francis, and Woodruff Counties. The elongated depression in Arkansas, Lonoke, and Prairie Counties has changed in areal extent or depth when compared to previous conditions of the aquifer. The area in Arkansas County at the southeastern half of the depression has not expanded horizontally during recent years, although the center of the depression has deepened. The area in Lonoke and Prairie Counties in the northwestern half of the depression has expanded horizontally in the deeper part of the depression. The 90-foot contour has expanded north and east in Lonoke County when compared with the 2004 potentiometric surface. Along the west side of Crowleys Ridge the 2006 potentiometric-surface map shows very little change in the area of this depression, although the deeper areas within the depression have expanded. A map showing the difference in water level was constructed using 645 differences in water-levels measured in 633 wells during 2002 and 2006. The difference in measured water levels from 2002 to 2006 ranged from -24.0 feet to 25.0 feet, with a mean of -2.0 feet. The largest decline of -24.0 feet occurred in Poinsett County and the largest rise of 25.0 feet occurred in Randolph County. Out of the 645 differences, 481 were declines (74.6 percent), 12 were no difference (values of 0.0 ft) (1.8 percent), and 152 were rises (23.6 percent). Long-term water-level trends were evaluated using hydrographs from 152 wells completed in the Mississippi River Valley alluvial aquifer for the period 1982 to 2006. The mean annual rise or decline in water level for the entire study area was -0.32 feet per year with a range of -1.28 to 0.77 feet per year. Independence and White Counties are the only counties with a mean annual rise from 1982 to 2006. Mean annual declines between -0.50 feet per year and 0.00 feet per year occurred in Arkansas, Ashley, Chicot, Clay, Craighead, Crittenden, Drew, Jefferson, Lee, Mississippi, Monroe, Phillips, Poinsett, Prairie, Pulaski, Randolph, and Woodruff Counties. Mean annual declines between -1.00 feet per year and -0.50 feet per year occurred in Cross, Desha, Greene, Jackson, Lincoln, Lonoke, and St. Francis Counties. The analysis of long-term water-level changes in Arkansas, Lonoke, and Prairie Counties shows the elongation of the depression in these three counties. Both Arkansas and Prairie Counties have two different rates of annual decline for the two hydrographs shown for each county. Water levels in the two wells near the Arkansas and White Rivers either have risen or declined at a slower rate than in the three wells in the center, northern, and western part of the depression. These rates of water-level change indicate that this depression is expanding in an elongated direction north and west into Lonoke and Prairie Counties. The depression west of Crowleys Ridge has five wells with hydrographs in or near the depression that can be used to characterize the rates of water-level change within the depression. Water samples were collected from 65 wells completed in the Mississippi River Valley alluvial aquifer and measured onsite for specific conductance and tempera

Scientific Investigations Report↗