SEARCH · USGS Science

Results for “Geological & Geophysical Surveys”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources

USGS2014

Refining the link between the Holocene development of the Mississippi River Delta and the geologic evolution of Cat Island, MS: implications for delta-associated barrier islands

The geologic evolution of barrier islands is profoundly influenced by the nature of the deposits underlying them. Many researchers have speculated on the origin and evolution of Cat Island in Mississippi, but uncertainty remains about whether or not the island is underlain completely or in part by deposits associated with the past growth of the Mississippi River delta. In part, this is due to a lack of comprehensive geological information offshore of the island that could augment previous stratigraphic interpretations based on terrestrial borings. An extensive survey of Cat Island and its surrounding waters was conducted, including shallow-water geophysics (e.g., high-resolution chirp seismic, side-scan sonar, and swath and single-beam bathymetry) and both terrestrial and marine vibracoring. High-resolution seismic data and vibracores from south and east of the island show two horizontally laminated silt units; marine radiocarbon dates indicate that they are St. Bernard delta complex (SBDC) deposits. Furthermore, seismic data reveal that the SBDC deposits taper off toward the southern shoreline of Cat Island and to the west, morphology consistent with the distal edge of a delta complex. The sedimentology and extent of each unit suggest that the lower unit may have been deposited during an earlier period of continuous river flow while the upper unit may represent reduced or sporadic river flow. OSL dates from the island platform (beneath beach ridge complexes) indicate three stages of terrestrial evolution: island emergence resulting from relative sea-level rise (~ 5400 ybp) island aggradation via littoral transport (~ 2500–4000 ybp) and island degradation due to delta-mediated changes in wave direction (present– ~ 3600 ybp). Finally, the combination of terrestrial and marine data shows that portions of Cat Island that are lower in elevation than the central part of the island are younger and are likely underlain by a thin layer of deltaic sediments. This underscores the potential for increased future vulnerability of barrier islands that develop adjacent to major river delta complexes.

Mississippi↗

USGS2017

Water-resources and land-surface deformation evaluation studies at Fort Irwin National Training Center, Mojave Desert, California

The U.S. Army Fort Irwin National Training Center (NTC), in the Mojave Desert, obtains all of its potable water supply from three groundwater basins (Irwin, Langford, and Bicycle) within the NTC boundaries (fig. 1; California Department of Water Resources, 2003). Because of increasing water demands at the NTC, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army, completed several studies to evaluate water resources in the developed and undeveloped groundwater basins underlying the NTC. In all of the developed basins, groundwater withdrawals exceed natural recharge, resulting in water-level declines. However, artificial recharge of treated wastewater has had some success in offsetting water-level declines in Irwin Basin. Additionally, localized water-quality changes have occurred in some parts of Irwin Basin as a result of human activities (i.e., wastewater disposal practices, landscape irrigation, and/or leaking pipes). As part of the multi-faceted NTC-wide studies, traditional datacollection methods were used and include lithological and geophysical logging at newly drilled boreholes, hydrologic data collection (i.e. water-level, water-quality, aquifer tests, wellbore flow). Because these data cover a small portion of the 1,177 square-mile (mi2 ) NTC, regional mapping, including geologic, gravity, aeromagnetic, and InSAR, also were done. In addition, ground and airborne electromagnetic surveys were completed and analyzed to provide more detailed subsurface information on a regional, base-wide scale. The traditional and regional ground and airborne data are being analyzed and will be used to help develop preliminary hydrogeologic framework and groundwater-flow models in all basins. This report is intended to provide an overview of recent water-resources and land-surface deformation studies at the NTC.

California↗

USGS2009

Fifty-year record of glacier change reveals shifting climate in the Pacific Northwest and Alaska, USA

Fifty years of U.S. Geological Survey (USGS) research on glacier change shows recent dramatic shrinkage of glaciers in three climatic regions of the United States. These long periods of record provide clues to the climate shifts that may be driving glacier change. The USGS Benchmark Glacier Program began in 1957 as a result of research efforts during the International Geophysical Year (Meier and others, 1971). Annual data collection occurs at three glaciers that represent three climatic regions in the United States: South Cascade Glacier in the Cascade Mountains of Washington State; Wolverine Glacier on the Kenai Peninsula near Anchorage, Alaska; and Gulkana Glacier in the interior of Alaska (fig. 1).

Alaska, British Columbia, Washington↗

USGS2014

Flow‐duration characteristics of Illinois streams

The paper entitled “An investigation of the flow‐duration characteristics of North Carolina streams,” by Thorndlke Saville and John Dargan Watson, which was published by the American Geophysical Union in its report of the Fourteenth Annual Meeting in 1933 (pp. 406–425), stimulated the writer, who is familiar with the streams discussed, having been assigned for several years to the United States Geological Survey offices that collected the base data. Knowing that there is a marked similarity in runoff‐characteristics of the western North Carolina streams and also that fairly good similarity is shown by New England streams within reasonable zones, he felt it would be desirable to carry the investigation to a part of the country where stream‐flow characteristics are diverse. The present investigation was therefore made to cover all the long‐time records in Illinois on streams of definite drainage‐area, particular attention being paid to comparisons of records from the same stream. The record on the Rock River at Afton, Wisconsin, was also included. The streams studied are listed in Table 1.

Illinois↗

USGS1982

Preliminary geotechnical and geophysical logs from drill hole 2C-80 in the Capps coal field, Cook Inlet region, Alaska

The drilling and logging information provided in this report was collected during September 1980 as part of the Energy Lands program of the U.S. Geological Survey. Drill hole 2C-80 is located in the Capps Coal Field, approximately 100 km (62 mi) west of Anchorage, Alaska (fig. 1). The drilling was undertaken to obtain information on the geotechnical characteristics of a part of the coal-bearing Tyonek Formation and overlying surficial deposits. The preliminary results of a previous drill hole (1C-79), located 1.3 km (0.8 mi) northeast of drill hole 2C-80, were reported by Chleborad and others (1980). The Tyonek Formation is early Oligocene to middle Miocene in age (Wolfe and Tanai, 1980). At the drill site it is overlain by a thin colluvial deposit of Quaternary age. The drilling and continuous core sampling penetrated 19.5 m (63.9 ft) of overburden, a major coal bed (Waterfall bed), and approximately 29 m (95.1 ft) of underlying material, to a total depth of 61 m (200 ft). Drill hole 2C-80 stratigraphically overlaps drill hole 1C-79 and continues down section approximately 33 m (108 ft). A proposed open pit coal-mining plan (Placer Amex, Inc., 1977, status report of December 1977) outlines a sequential mining and reclamation scheme for five areas in the Capps Coal Field. Figure 2 shows the location of drill holes 2C-80 and 1C-79 with respect to the proposed mining areas as well as selected surface features. A general description of the geology and natural hazards of the region are given by Schmoll and others (1981). The generalized lithology interpreted from core obtained from drilling and supplemented by outcrop mapping accomplished during the 1979 and 1980 field seasons is presented in figure 3. A more detailed lithologic log is presented as part of the geotechnical log. The geotechnical and geophysical logs presented herein (pls. 1 and 2) provide basic physical-property and engineering data useful in predicting the response of geologic materials to proposed large-scale coal mining and related development, and in identifying and assessing potential geologic hazards.

Alaska↗

USGS2007

Crustal structure of Wrangellia and adjacent terranes inferred from geophysical studies along a transect through the northern Talkeetna Mountains

Recent investigations of the Talkeetna Mountains in south-central Alaska were undertaken to study the region's framework geophysics and to reinterpret structures and crustal composition. Potential field (gravity and magnetic) and magnetotelluric (MT) data were collected along northwest-trending profiles as part of the U.S. Geological Survey's Talkeetna Mountains transect project. The Talkeetna Mountains transect area comprises eight 1:63,360 quadrangles (∼9500 km 2 ) in the Healy and Talkeetna Mountains 1° × 3° sheets that span four major lithostratigraphic terranes ( Glen et al., this volume ) including the Wrangellia and Peninsular terranes and two Mesozoic overlap assemblages inboard (northwest) of Wrangellia. These data were used here to develop 2½-dimensional models for the three profiles.

Special Paper of the Geological Society of America↗

USGS2014

Sediment data collected in 2012 from the northern Chandeleur Islands, Louisiana

As part of the Barrier Island Evolution Research project, scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center collected sediment samples from the northern Chandeleur Islands in March and September 2012. The overall objective of this project, which integrates geophysical (bathymetric, seismic, and topographic) and sedimentologic data, is to better understand the depositional and erosional processes that drive the morphologic evolution of barrier islands over annual to interannual timescales (1 to 5 years). Between June 2010 and April 2011, in response to the Deepwater Horizon oil spill, the State of Louisiana constructed a sand berm extending more than 14 kilometers along the northern Chandeleur Islands platform. The construction of the berm provided a unique opportunity to investigate how this new sediment source will interact with and affect the morphologic evolution of the barrier-island system. Data collected from this study will be used to describe differences in the physical characteristics and spatial distribution of sediments both along the axis of the berm and also along transects across the berm and onto the adjacent barrier island. Comparison of these data with data from subsequent sampling efforts will provide information about sediment interactions and movement between the berm and the natural island platform, improving our understanding of short-term morphologic change and processes in this barrier-island system. This data series serves as an archive of sediment data collected in March and September 2012 from the Chandeleur Islands sand berm and adjacent barrier-island environments. Data products include descriptive core logs, core photographs and x-radiographs, results of sediment grain-size analyses, sample location maps, and Geographic Information System data files with accompanying formal Federal Geographic Data Committee metadata.

Louisiana↗

USGS2025

Quantitative mineral resource assessment of lithium pegmatite deposits in the Appalachian Orogen, USA

Lithium is classified as a U.S. critical mineral commodity, and its demand is projected to drastically increase through 2040, driven by electric vehicle production and energy storage applications (IEA 2021).Most global lithium production is not in the United States increasing vulnerability to a supply disruption. The U.S. Geological Survey is actively assessing domestic lithium deposits including lithium-bearing pegmatites in the Appalachian orogen. Permissive tracts for lithium pegmatite deposits were delineated by integrating lithological, tectonic, geochemical, geophysical, and mineral occurrence data. The geospatial data and permissive tracts were used to estimate the number of undiscovered lithium pegmatite deposits. Estimates were then integrated into probabilistic simulations along with a new global lithium pegmatite grade and tonnage dataset to quantify potential contained undiscovered lithium resources. An economic filter was used to estimate the amount of potentially recoverable undiscovered resources. Preliminary computations for the northern Appalachians, including application of the economic filter to the median recoverable contained resource, yields 900,000 metric tons of Li 2 O that correspond to enough Li 2 O to replace 127 years of import reliance at the current rate (7,100 t Li 2 O/yr; USGS, 2025). For the southern Appalachians, preliminary computations yielded 1,430,000 metric tons of Li 2 O, which corresponds to 201 years of import reliance.

Alabama, Connecticut, Delaware, Georgia, Maine, Ma↗

USGS1991

Publications of the Branch of Atlantic Marine Geology for Calendar Year 1990

This U.S. Geological Survey Open-File Report [extract] contains a listing of publications authored or co-authored by members of the Branch of Atlantic Marine Geology and published in calendar year 1990. The Branch conducts a broad geologic and geophysical research and mapping program, primarily along the U.S. Atlantic Margin, in the Great Lakes, the Gulf of Mexico, the Caribbean and polar regions. A long range objective of this program is to develop a comprehensive understanding of the geology of the continental margin and a predictive capability to guide and assess the consequences of its use. Headquarters of the Branch of Atlantic Marine Geology are located in Woods Hole, MA., and personnel are located in Woods Hole, MA., St Petersburg, FL., Reston, VA., Denver, CO., and San Juan, Puerto Rico. A brochure describing the Branch of Atlantic Marine Geology may be obtained by writing to Chief, Branch of Atlantic Marine Geology, Quissett Campus, Woods Hole, MA 02543. Results of Branch investigations are distributed in a variety of ways, including maps, journal articles, abstracts and U.S.G.S. publications. Copies of U.S.G.S. Open File Reports may be obtained from the author. Book publications can be obtained from U.S. Geological Survey, Books and Reports Sales, Federal Center, Box 25425, Denver, CO 80225. Copies of U.S.G.S. Maps may be obtained from the U.S. Geological Survey, Map Sales, Federal Center, Box 25286, Denver, CO 80225.

Open-File Report↗

USGS1994

Publications of the Branch of Atlantic Marine Geology for Calendar Year 1993

This U.S. Geological Survey Open-File Report [extract] contains a listing of publications authored or co-authored by members of the Branch of Atlantic Marine Geology and published in calendar year 1993. The Branch conducts a broad geologic and geophysical research and mapping program, primarily along the U.S. Atlantic Margin, in the Great Lakes, the Gulf of Mexico, the Caribbean and polar regions. A long range objective of this program is to develop a comprehensive understanding of the geology of the continental margin and a predictive capability to guide and assess the consequences of its use. Headquarters of the Branch of Atlantic Marine Geology are located in Woods Hole, MA., and personnel are located in Woods Hole, MA., St Petersburg, FL., Reston, VA., Denver, CO., and San Juan, Puerto Rico. A brochure describing the Branch of Atlantic Marine Geology may be obtained by writing to Chief, Branch of Atlantic Marine Geology, Quissett Campus, Woods Hole, MA 02543. Results of Branch investigations are distributed in a variety of ways, including maps, journal articles, abstracts and U.S.G.S. publications. Copies of U.S.G.S. Open File Reports may be obtained from the author. Book publications can be obtained from U.S. Geological Survey, Books and Reports Sales, Federal Center, Box 25425, Denver, CO 80225. Copies of U.S.G.S. Maps may be obtained from the U.S. Geological Survey, Map Sales, Federal Center, Box 25286, Denver, CO 80225.

Open-File Report↗

USGS1992

Geophysically inferred structural and lithologic map of the precambrian basement in the Joplin 1° x 2° quadrangle, Kansas and Missouri

This report is an analysis of regional gravity and aeromagnetic data that was carried out as part of a Conterminuous United States Mineral Assessment Program (CUSMAP) study of the Joplin 1° X 2° quadrangle, Kansas and Missouri. It is one in a series of reports representing a cooperative effort between the U.S. Geological Survey, Kansas Geological Survey, and Missouri Department of Natural Resources, Division of Geology and Land Survey. The work presented here is part of a larger project whose goal is to assess the mineral resource potential of the Paleozoic sedimentary section and crystalline basement within the quadrangle. Reports discussing geochemical, geological, and various other aspects of the study area are included in this Miscellaneous Field Studies Map series as MF-2125-A through MF-2125-E. Geophysical interpretation of Precambrian crystalline basement lithology and structure is the focus of this report. The study of the crystalline basement is complicated by the lack of exposures due to the presence of a thick sequence of Phanerozoic sedimentary cover. In areas where there are no outcrops, the geologist must turn to other indirect methods to assist in an understanding of the basement. Previous investigations of the buried basement in this region used available drill hole data, isotope age information, and regional geophysical data (Sims, 1990; Denison and others, 1984; Bickford and others, 1986). These studies were regional in scope and were presented at state and multistate scales. The work documented here used recently collected detailed gravity and aeromagnetic data to enhance the regional geologic knowledge of the area. Terrace-density and terrace-magnetization maps were calculated from the gravity and aeromagnetic data, leading directly to inferred physical-property (density and magnetization) maps. Once these maps were produced, the known geology and drill-hole data were reconciled with the physical-property maps to form a refined structural and lithologic map of the crystalline basement.

Kansas, Missouri↗

USGS2010

Compilation of Water-Resources Data and Hydrogeologic Setting for the Allison Woods Research Station in Iredell County, North Carolina, 2005-2008

Water-resources data were collected to describe the hydrologic conditions at the Allison Woods research station near Statesville, North Carolina, in the Piedmont Physiographic Province of North Carolina. Data collected by the U.S. Geological Survey and the North Carolina Department of Environment and Natural Resources, Division of Water Quality, from April 2005 through September 2008 are presented in this report. Data presented include well-construction characteristics and periodic groundwater-level measurements for 29 wells, borehole geophysical logs for 8 wells, hourly groundwater-level measurements for 5 wells, continuous water-quality measurements for 3 wells, periodic water-quality samples for 12 wells and 1 surface-water station, slug-test results for 11 wells, and shallow groundwater-flow maps. In addition, the geology and hydrogeology at the site are summarized.

North Carolina↗

USGS2010

Lithologic and physicochemical properties and hydraulics of flow in and near the freshwater/saline-water transition zone, San Antonio segment of the Edwards aquifer, south-central Texas, based on water-level and borehole geophysical log data, 1999-2007

The freshwater zone of the San Antonio segment of the Edwards aquifer in south-central Texas (hereinafter, the Edwards aquifer) is bounded to the south and southeast by a zone of transition from freshwater to saline water (hereinafter, the transition zone). The boundary between the two zones is the freshwater/saline-water interface (hereinafter, the interface), defined as the 1,000-milligrams per liter dissolved solids concentration threshold. This report presents the findings of a study, done by the U.S. Geological Survey in cooperation with the San Antonio Water System, to obtain lithologic properties (rock properties associated with known stratigraphic units) and physicochemical properties (fluid conductivity and temperature) and to analyze the hydraulics of flow in and near the transition zone of the Edwards aquifer on the basis of water-level and borehole geophysical log data collected from 15 monitoring wells in four transects during 1999-2007. No identifiable relation between conductivity values from geophysical logs in monitoring wells in all transects and equivalent freshwater heads in the wells at the times the logs were run is evident; and no identifiable relation between conductivity values and vertical flow in the boreholes concurrent with the times the logs were run is evident. The direction of the lateral equivalent freshwater head gradient and thus the potential lateral flow at the interface in the vicinity of the East Uvalde transect fluctuates between into and out of the freshwater zone, depending on recharge and withdrawals. Whether the prevailing direction on average is into or out of the freshwater zone is not clearly indicated. Equivalent freshwater head data do not indicate a prevailing direction of the lateral gradient at the interface in the vicinity of the Tri-County transect. The prevailing direction on average of the lateral gradient and thus potential lateral flow at the interface in the vicinity of the Kyle transect likely is from the transition zone into the freshwater zone. The hypothesis regarding the vertical gradient at the East Uvalde transect, and thus the potential for vertical flow near an interface conceptualized as a surface sloping upward in the direction of the dip of the stratigraphic units, is that the potential for vertical flow fluctuates between into and out of the freshwater zone, depending on recharge and withdrawals. At the Tri-County transect, a downward gradient on the fresh-water side of the interface and an upward gradient on the saline-water side are evidence of opposing potentials that appear to have stabilized the position of the interface over the range of hydrologic conditions that occurred at the times the logs were run. At the Fish Hatchery transect, an upward gradient on the saline-water side of the interface, coupled with the assumption of a sloping interface, implies a vertical gradient from the transition zone into the freshwater zone. This potential for vertical movement of the interface apparently was opposed by the potential (head) on the freshwater side of the interface that kept the interface relatively stable over the range of hydrologic conditions during which the logs were run. The five flow logs for Kyle transect freshwater well KY1 all indicate upward flow that originates from the Glen Rose Limestone, the uppermost unit of the Trinity aquifer; and one log for well KY2 shows upward flow entering the borehole from the Trinity aquifer. These flow data constitute evidence of the potential for flow from the Trinity aquifer into the Edwards aquifer in the vicinity of the Kyle transect. Subsurface temperature data indicate that flow on average is more active, or vigorous, on the freshwater side of the interface than on the saline-water side. A hydraulic connection between the transition zone and the freshwater zone is indicated by similar patterns in the hydrographs of the 15 transect monitoring wells in and near the transition zone and three county index wel

Texas↗

USGS2003

Cruise report for A1-02-SC southern California CABRILLO project, Earthquake Hazards Task

A two-week marine geophysical survey obtained sidescan-sonar images and multiple sets of high-resolution seismic-reflection profiles in the southern California offshore area between Point Arguello and Point Dume. The data were obtained to support two project activities of the United States Geological Survey (USGS) Coastal and Marine Geology (CMG) Program: (1) the evaluation of the geologic hazards posed by earthquake faults and landslides in the offshore areas of Santa Barbara Channel and western Santa Monica Basin and (2) determine the location of active hydrocarbon seeps in the vicinity of Point Conception as part of a collaborative study with the Minerals Management Service (MMS). The 2002 cruise, A1-02- SC, is the fourth major data-collection effort in support of the first objective (Normark et al., 1999a, b; Gutmacher et al., 2000). A cruise to obtain sediment cores to constrain the timing of deformation interpreted from the geophysical records is planned for the summer of 2003.

California↗

USGS1985

Management of ground water and evolving hydrogeologic studies in New Jersey : a heavily urbanized and industrialized state in the northeastern United States

New Jersey is the most densely populated and one of the most industrialized states in the United States. An abundance of freshwater and proximity to major northeastern metropolitan centers has facilitated this development. Pumpage of freshwater from all aquifers in the State in 1980 was 730 million gallons per day (2.76 million cubic meters per day). Management and efficient development of the ground-water resources of the State are the responsibility of the New Jersey Department of Environmental Protection. Laws have been enacted and updated by the State legislature to manage water allocation and to control the disposal of hazardous wastes. Present resource management is guided by the New Jersey Water-Supply Master Plan of 1981. Funding for management activities is partially derived from the sale of state-approved bonds. Effective planning and regional management require accurate and up-to-date hydrologic information and analyses. The U.S. Geological Survey, in cooperation with the New Jersey Geological Survey, is conducting three intensive ground-water studies involving the collection and interpretation of hydrologic data to meet the urgent water-management needs of New Jersey. These studies are part of a long-term cooperative program and are funded through the Water-Supply Bond Act of 1981. They began in 1983 and are scheduled to be completed in 1988. The project areas are situated in the New Jersey part of the Atlantic Coastal Plain in and near Atlantic City, Camden, and South River. They range in size from 400 to 1,200 mil (1,040 to 3,120 km2). The studies are designed to define the geology, hydrology, and geochemistry of the local ground-water systems. The results of these studies will enable the State to address more effectively major problems in these areas such as declining water levels, overpumping, saltwater intrusion, and ground-water contamination resulting from the improper disposal of hazardous wastes. Specific objectives of these studies by the U.S. Geological Survey are to (1) develop an accurate and up-to-date hydrogeologic data base, (2) design and implement a data-collection program and establish a computerized information management system, (3) refine the conceptualization of the ground-water flow system, and (4) define the geochemistry of the aquifer system by conducting a water-quality appraisal. The objectives are accomplished by standard hydrogeologic methods. Information concerning hydrogeologic framework, ground-water levels, water use, hydraulic characteristics, and water quality in the study areas is compiled from all available sources. Additional data needed are collected through well inventories, surface geophysical surveys, water-quality samplings, water-level measurements, and a well-drilling program. Interpretation of the flow system is based on the use of standard analytical techniques and digital flow modeling. Calibrated flow models will provide ground-water managers with a mechanism to develop and test regional water-supply strategies. Definition of the geochemistry of the aquifer system is accomplished through a variety of methods which depend on the problems and available data in the particular study area. The approach includes statistical analysis of water-quality data, reaction-path modeling, and determination of the movement of chemical constituents using analytical and numerical modeling techniques. A combined staff of 25 to 30 professionals and technicians from the New Jersey District office of the U.S. Geological Survey is committed to the three studies. The staff has specialists in geohydrology, numerical modeling, geochemistry, geophysics, and computer science. The findings of these studies will be published in data reports, interpretive reports, instructional manuals and journal articles.

New Jersey↗

USGS1978

Evaluation of Baltazor known geothermal resources area, Nevada

By virtue of the Geothermal Steam Act of 1970, the U.S. Geological Survey is required to appraise geothermal resources of the United States prior to competitive lease sales. This appraisal involves coordinated input from a variety of disciplines, starting with reconnaissance geology and geophysics. This paper describes how the results of several geophysical methods used in KGRA evaluation were interpreted by the authors, two geophysicists, involved with both the Evaluation Committee and the research program responsible for obtaining and interpreting the geophysical data to be used by the committee. ?? 1979.

Geothermics↗

USGS1978

Clarence Allen talks about the responsibilities in earthquake prediction

Dr. Clarence R. Allen is professor of geology and geophysics at the California Institute of Technology. He has been a member of advisory panels to the Executive Office of the President, National Academy of Sciences, National Science Foundation, U.S Geological Survey, UNESCO, California State Mining and Geology Board, and the California Department of Water Resources. Dr. Allen has been President of both the Geological Society of America and the Seismological Society of America (SSA). The title of this interview is based on his presidential address to the SSA in 1976.

Earthquake Information Bulletin (USGS)↗

USGS1988

Structure and stratigraphy of the western Florida shelf; Part I, Multichannel reflection seismic data

This paper presents a synthesis of multichannel seismic data on the Western Florida shelf (Fig. 1). This work is part of an ongoing regional program conducted by the U.S. Geological Survey in studying the Exclusive Economic Zones of the United States. The data include 1270 km of 32-fold, common-depth-point (CDP), reflection seismic line obtained with a 3200 m, 64 channel, hydrophone streamer and a 2000 in 3 airgun array. The rationale for the line layout was to tie eight key exploration wells among the 14 existing in federal waters prior to 1980 to 4 key wells in Florida. An attempt was also made to connect our survey with that of the University of Texas Institute of Geophysics in the deep Gulf of Mexico basin. A second set of 1500 km of 24-fold CDP data were collected using a 1200 m, 24-channel streamer and a 550 in 3 airgun source. This set was intended to tie additional wells, drilled between 1979 and 1983, and to infill our original net. Gravity and magnetic measurements were also made along these lines. Our subsurface information in federal waters consists of well logs and files released to us initially by the Conservation Division of the U.S. Geological Survey and subsequently by the U.S. Minerals Management Service. Most information from wells in state waters was provided by the Florida Geological Survey. Table 1 lists wells included in our study and summarizes the types of logs and other information available from each well. Spontaneous potential or gamma ray, resistivity or conductivity, sonic and density logs were generally available. Lithologic information, paleontologic and log picks on stratigraphic units and dip-meter data were also common. Check shot surveys for velocity analysis were available in three wells.

Florida↗