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At least 1,639 records · Page 91Linked to original sources
USGS1982

Geologic and structure map of the Choteau 1° x 2° quadrangle, western Montana: A digital database

The geologic and structure map of Choteau 1 x 2 degree quadrangle (Mudge and others, 1982) was originally converted to a digital format by Jeff Silkwood (U.S. Forest Service and completed by the U.S. Geological Survey staff and contractor at the Spokane Field Office (WA) in 2000 for input into a geographic information system (GIS). The resulting digital geologic map (GIS) database can be queried in many ways to produce a variey of geologic maps. Digital base map data files (topography, roads, towns, rivers and lakes, etc.) are not included: they may be obtained from a variety of commercial and government sources. This database is not meant to be used or displayed at any scale larger than 1:250,000 (e.g. 1:100,000 or 1:24,000. The digital geologic map graphics and plot files (chot250k.gra/.hp/.eps and chot-map.pdf) that are provided in the digital package are representations of the digital database. They are not designed to be cartographic products.

Montana↗
USGS1995

Geologic map and structure sections of the Clear Lake Volcanics, Northern California

The Clear Lake Volcanics are located in the California Coast Ranges about 150 km north of San Francisco. This Quaternary volcanic field has erupted intermittently since 2.1 million years ago. This volcanic field is considered a high-threat volcanic system (Ewert and others, 2005) The adjacent Geysers geothermal field, largest power-producing geothermal field in the world, is powered by the magmatic heat source for the volcanic field. This report consists of three sheets that include the geologic map, one table, two figures, three cross sections, description of map units, charts of standard and diagrammatic correlation of map units, and references. This map supersedes U.S. Geological Survey Open-File Report 76-751. Descriptions of map units are grouped by geographic area. Summaries of the evolution, chemistry, structure, and tectonic setting of the Clear Lake Volcanics are given in Hearn and others (1981) and Donnelly-Nolan and others (1981). The geology of parts of the area underlain by the Cache Formation is based on mapping by Rymer (1981); the geology of parts of the areas underlain by the Sonoma Volcanics, Franciscan assemblage, and Great Valley sequence is based on mapping by McLaughlin (1978). Volcanic compositional map units are basalt, basaltic andesite, andesite, dacite, rhyodacite, and rhyolite, based on SiO2 content. Included in this report are maps showing the distribution of volcanic rocks through time and a chart showing erupted volumes of different lava types through time. A table gives petrographic data for each map unit by mineral type, abundance, and size. Most ages are potassium-argon (K/Ar) ages determined for whole-rock samples and mineral separates by Donnelly-Nolan and others (1981), unless otherwise noted. A few ages are carbon-14 ages or were estimated from geologic relationships. Magnetic polarities are from Mankinen and others (1978; 1981) or were determined in the field by B.C. Hearn, Jr., using a portable fluxgate magnetometer. Thickness for most units is estimated from topographic relief except where drill-hole data were available.

California↗
USGS1991

Map showing structure contours on the top of the upper Jurassic Morrison Formation, Powder River basin, Wyoming and Montana

This map is one in a series of U.S. Geological Survey Miscellaneous Field Studies (MF) maps showing computer-generated structure contours, isopachs, and cross sections of selected formations in the Powder River basin, Wyoming and Montana. The map and cross sections were constructed from information stored in a U.S. Geological Survey Evolution of Sedimentary Basins data base. This data base contains picks of geologic formation and (or) unit tops and bases determined from electric resistivity and gamma-ray logs of 8,592 wells penetrating Tertiary and older rocks in the Powder River basin. Well completion cards (scout tickets) were reviewed and compared with copies of all logs, and formation or unit contacts determined by N. M. Denson, D.L. Macke, R. R. Schumann and others. This isopach map is based on information from 2,429 of these wells that penetrate the Minnelusa Formation and equivalents.

Montana;Wyoming↗
USGS1994

Map showing structure of the Mississippi Valley Graben in the vicinity of New Madrid, Missouri

This is one of a series of five seismotectonic maps of the seismically active New Madrid area in southeast Missouri and adjacent parts of Arkansas, Kentucky, and Tennessee (table 1). We cannot legibly show all the seismotectonic data on a single map, therefore each of the five maps in this series groups a different type of related information. Rhea and others (1994) summarized the background and purpose of the seismotectonic map folio. The different types of data shown on this map are described in table 2. Except for a few exposed faults, all structures shown on the map are in Paleozoic sedimentary rocks of the midcontinent or underlying metamorphic and igneous basement rocks of presumed Precambrian age (Dart, 1992; Muehlberger, 1992). Edge of Mississippi Embayment, as shown on the map, marks the contact between gently dipping, exposed Paleozoic rocks to the northwest (Anderson and others, 1979) and unconformably overlying, flat or gently dipping Mesozoic and Cenozoic strata of the embayment to the southeast.

Missouri↗
USGS2001

Geologic maps and structure sections of the southwestern Santa Clara Valley and southern Santa Cruz Mountains, Santa Clara and Santa Cruz Counties, California

This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (scvmf.ps, scvmf.pdf, scvmf.txt), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗
USGS2001

The internal structure of sand bars on the Colorado River, Grand Canyon, as determined by ground-penetrating radar

High-resolution, subsurface imagery from ground-penetrating radar (GPR) has revealed the internal structure of sand bars at seven sites on the Colorado River, Grand Canyon. Based on reconnaissance-level surveys, we recognized three stratigraphic units and several intervening unconformities. Unit A, which exhibits hyperbolic reflections and always occurs at the base of the section, is interpreted as bedrock and/or talus. Unit B is a commonly observed sand deposit that overlies unit A and is characterized by reflections that gently dip down toward the river axis. Unit C is a sand deposit up to 2 m thick that always occurs at the top of the section and may represent a flood deposit from 1983. This study demonstrates the utility of GPR for non-destructive investigation of sand-bar thickness and the stratigraphic record of flood events in the Grand Canyon.

Arizona↗
USGS2001

Outcrop structural data from parts of the Petersburg and Sumdum 1:250,000-scale quadrangles, southeastern Alaska

This report presents a compilation of 4203 measurements of outcrop structures from part of the Petersburg 1:250,000-scale quadrangle in southeastern Alaska. We collected 1966 measurements, and an additional 2237 unpublished measurements were compiled from field notebooks a from a field mapping effort in the late 1970’s and early 1980’s. These data are listed in spreadsheet and derivative formats. The data includes the latitude and longitude of each measurement, the type of measurement and its orientation.

Alaska↗
USGS2001

Outcrop structural data from Wales Group and adjacent rocks, Dall and Prince of Wales islands, southeastern Alaska

This report presents a compilation of 3224 measurements of outcrop structures from Wales Group and adjacent strata on Dall and Prince of Wales Islands, southeastern Alaska. We collected 2230 measurements, an additional 344 were digitized from the map of Eberlein and others (1983), and an additional 650 come from the map of Herreid and others (1978). These data are listed in Excel spreadsheet, tab-delimited, and PDF formats. The data includes the latitude and longitude of each measurement, the type of measurement and its orientation.

Alaska↗
USGS2003

Structure of the Tucson Basin, Arizona from gravity and aeromagnetic data

Interpretation of gravity and high-resolution aeromagnetic data reveal the three-dimensional geometry of the Tuscson Basin, Arizona and the lithology of its basement. Limited drill hole and seismic data indicate that the maximum depth to the crystalline basement is approximately 3600 meters and that the sedimentary sequences in the upper ~2000 m of the basin were deposited during the most recent extensional episode that commenced about 13 Ma. The negative density contrasts between these upper Neogene and Quaternary sedimentary sequences and the adjacent country rock produce a Bouguer residual gravity low, whose steep gradients clearly define the lateral extent of the upper ~2000m of the basin. The aeromagnetic maps show large positive anomalies associated with deeply buried, late Cretaceous-early Tertiary and mid-Tertiary igneous rocks at and below the surface of the basin. These magnetic anomalies provide insight into the older (>13 Ma) and deeper structures of the basin. Simultaneous 2.5-dimensional modeling of both gravity and magnetic anomalies constrained by geologic and seismic data delineates the thickness of the basin and the dips of the buried faults that bound the basin. This geologic-based forward modeling approach to using geophysical data is shown to result in more information about the geologic and tectonic history of the basin as well as more accurate depth to basement determinations than using generalized geophysical inversion techniques.

Open-File Report↗
USGS2004

Invertebrate Paleontology of the Wilson Grove Formation (Late Miocene to Late Pliocene), Sonoma and Marin Counties, California, with some Observations on Its Stratigraphy, Thickness, and Structure

The Wilson Grove Formation is exposed from Petaluma north to northern Santa Rosa, and from Bennett Valley west to Bodega Bay. A fauna of at least 107 invertebrate taxa consisting of two brachiopods, 95 mollusks (48 bivalves and 46 gastropods), at least eight arthropods, and at least two echinoids have been collected, ranging in age from late Miocene to late Pliocene. Rocks and fossils from the southwest part of the outcrop area, along the Estero de San Antonio, were deposited in a deep-water marine environment. At Meacham Hill, near the Stony Point Rock Quarry, and along the northern margin of the outcrop area at River Road and Wilson Grove, the Wilson Grove Formation was deposited in shallow marine to continental environments. At Meacham Hill, these shallow water deposits represent a brackish bay to continental environment, whereas at River Road and Wilson Grove, fossils suggest normal, euhaline (normal marine salinity) conditions. A few taxa from the River Road area suggest water temperatures slightly warmer than along the adjacent coast today because their modern ranges do not extend as far north in latitude as River Road. In addition, fossil collections from along River Road contain the bivalve mollusks Macoma addicotti (Nikas) and Nuttallia jamesii Roth and Naidu, both of which are restricted to the late Pliocene. The late Miocene Roblar tuff of Sarna-Wojcicki (1992) also crops out northeast of the River Road area and underlies the late Pliocene section at Wilson Grove by almost 300 m. Outcrops in the central part of the region are older than those to the northeast, and presumably younger than deposits to the southwest. The Roblar tuff of Sarna-Wojcicki (1992) occurs at Steinbeck Ranch in the central portion of the outcrop area. At Spring Hill, also in the central part of the outcrop area, the sanddollar Scutellaster sp., cf. S. oregonensis (Clark) has been recently collected. This species, questionably identified here, is restricted to the late Miocene from central California through Oregon. Outcrops at Salmon Creek, northeast of Steinbeck Ranch and also in the central part of the outcrop area, contain Aulacofusus? recurva (Gabb) and Turcica brevis Stewart, which are both restricted to the Pliocene, as well as Lirabuccinum portolaensis (Arnold) known from the early Pliocene of central and northern California and into the late Pliocene in southern California. These data suggest an overall pattern of older rocks and deeper water to the south and west, and younger rocks and shallower water to the east and north. Outcrops to the southwest, south of the Bloomfield fault, are not well dated but presumably are older than the late Miocene Roblar tuff of Sarna-Wojcicki (1992). Fossils in this part of the section are rare and are not useful in determining a precise age or environment of deposition for the lower part of the Wilson Grove Formation. However, sedimentary sequences and structures in the rocks here are useful and suggest probable outer shelf and slope water depths. Lituyapecten turneri (Arnold) which occurs in this part of the section has previously been restricted to the Pliocene, but its occurrence below the Roblar tuff of Sarna-Wojcicki (1992) indicates a revised late Miocene age for this taxon. Three possibly new gastropods (Mollusca) are reported here: Calyptraea (Trochita) n. sp. and Nucella sp., aff. N. lamellosa (Gmelin), both from the Bloomfield Quarry area, and Acanthinucella? n. sp. from the River Road area. These species are not described here because this venue is deemed insufficient for the description of new taxa.

Open-File Report↗
USGS2006

Inversion of Gravity Data to Define the Pre-Cenozoic Surface and Regional Structures Possibly Influencing Groundwater Flow in the Rainier Mesa Region, Nye County, Nevada

A three-dimensional inversion of gravity data from the Rainier Mesa area and surrounding regions reveals a topographically complex pre-Cenozoic basement surface. This model of the depth to pre-Cenozoic basement rocks is intended for use in a 3D hydrogeologic model being constructed for the Rainier Mesa area. Prior to this study, our knowledge of the depth to pre-Cenozoic basement rocks was based on a regional model, applicable to general studies of the greater Nevada Test Site area but inappropriate for higher resolution modeling of ground-water flow across the Rainier Mesa area. The new model incorporates several changes that lead to significant improvements over the previous regional view. First, the addition of constraining wells, encountering old volcanic rocks lying above but near pre-Cenozoic basement, prevents modeled basement from being too shallow. Second, an extensive literature and well data search has led to an increased understanding of the change of rock density with depth in the vicinity of Rainier Mesa. The third, and most important change, relates to the application of several depth-density relationships in the study area instead of a single generalized relationship, thereby improving the overall model fit. In general, the pre-Cenozoic basement surface deepens in the western part of the study area, delineating collapses within the Silent Canyon and Timber Mountain caldera complexes, and shallows in the east in the Eleana Range and Yucca Flat regions, where basement crops out. In the Rainier Mesa study area, basement is generally shallow (< 1 km). The new model identifies previously unrecognized structures within the pre-Cenozoic basement that may influence ground-water flow, such as a shallow basement ridge related to an inferred fault extending northward from Rainier Mesa into Kawich Valley.

Open-File Report↗
USGS2007

Near-Surface Structure and Velocities of the Northeastern Santa Cruz Mountains and the Western Santa Clara Valley, California, From Seismic Imaging

Introduction The Santa Clara Valley (SCV) is located in the southern San Francisco Bay area of California and is bounded by the Santa Cruz Mountains to the southwest, the Diablo Ranges to the northeast, and the San Francisco Bay to the north (Fig. 1). The SCV, which includes the City of San Jose, numerous smaller cities, and much of the high-technology manufacturing and research area commonly referred to as the Silicon Valley, has a population in excess of 1.7 million people (2000 U. S. Census;http://quickfacts.census.gov/qfd/states/06/06085.html The SCV is situated between major active faults of the San Andreas Fault system, including the San Andreas Fault to the southwest and the Hayward and Calaveras faults to the northeast, and other faults inferred to lie beneath the alluvium of the SCV (CWDR, 1967; Bortugno et al., 1991). The importance of the SCV as a major industrial center, its large population, and its proximity to major earthquake faults are important considerations with respect to earthquake hazards and water-resource management. The fault-bounded alluvial aquifer system beneath the valley is the source of about one-third of the water supply for the metropolitan area (Hanson et al., 2004). To better address the earthquake hazards of the SCV, the U.S. Geological Survey (USGS) has undertaken a program to evaluate potential seismic sources, the effects of strong ground shaking, and stratigraphy associated with the regional aquifer system. As part of that program and to better understand water resources of the valley, the USGS and the Santa Clara Valley Water District (SCVWD) began joint studies to characterize the faults, stratigraphy, and structures beneath the SCV in the year 2000. Such features are important to both agencies because they directly influence the availability and management of groundwater resources in the valley, and they affect the severity and distribution of strong shaking from local and regional earthquakes sources that may affect reservoirs, pipelines, and flood-protection facilities maintained by SCVWD. As one component of these joint studies, the USGS acquired an approximately 10-km-long, high-resolution, combined seismic reflection/refraction transect from the Santa Cruz Mountains to the central SCV in December 2000 (Figs. 1 and 2a,b). The overall seismic investigation of the western Santa Clara Valley also included an ~18-km-long, lower-resolution (~50-m sensor) seismic imaging survey from the central Santa Cruz Mountains to the central part of the valley (Fig. 1). Collectively, we refer to these seismic investigations as the 2000 western Santa Clara Seismic Investigations (SCSI). Results of the high-resolution investigation, referred to as SCSI-HR, are presented in this report, and Catchings et al. (2006) present results of the low-resolution investigation (SCSI-LR) in a separate report. In this report, we present data acquisition parameters, unprocessed and processed seismic data, and interpretations of the SCSI-HR seismic transect.

Open-File Report↗
USGS2007

Magnetic anomalies northeast of Cape Adare, northern Victoria Land (Antarctica), and their relation to onshore structures

An aeromagnetic survey was flown over the offshore region northeast of Cape Adare and the magnetic anomalies compared to onshore structures between Pennell Coast and Tucker Glacier. The magnetic anomalies show two nearly orthogonal major trends. NNW-SSE trending anomalies northeast of Cape Adare represent seafloor spreading within the Adare Trough. A connection of these anomalies to the Northern Basin of the Ross Sea is not clear. Onshore faults are closely aligned to offshore anomalies. Main trends are NW-SE to NNW-SSE and NE-SW to NNESSW. NNW-SSE oriented dextral-transtensional to extensional faults parallel the Adare Peninsula and Adare Trough anomalies. NE-SW trending normal faults appear to segment the main Hallett volcanic bodies.

Open-File Report↗
USGS2007

Airborne laser swath mapping of the Denton Hills, Transantarctic Mountains, Antarctica: Applications for structural and glacial geomorphic mapping

High-resolution digital elevation data acquired by airborne laser scanning (ALS) for the Denton Hills, along the coastal foothills of the Royal Society Range, Transantarctic Mountains, are examined for applications to bedrock and glacial geomorphic mapping. Digital elevation models (DEMs), displayed as shaded-relief images and slope maps, portray geomorphic landscape features in unprecedented detail across the region. Structures of both ductile and brittle origin, ranging in age from the Paleozoic to the Quaternary, can be mapped from the DEMs. Glacial features, providing a record of the limits of grounded ice, of lake paleoshorelines, and of proglacial lake-ice conveyor deposits, are also prominent on the DEMs. The ALS-derived topographic data have great potential for a range of mapping applications in regions of ice-free terrain in Antarctica

Open-File Report↗
USGS2007

Stratigraphy, structure, and geologic and coastal hazards in the Penuelas to Salinas area, southern Puerto Rico: A compendium of published literature

The Puerto Rico Electrical Power Authority has proposed construction of a pipeline to convey natural gas from the municipio of Peñuelas to the Aguirre thermoelectric power plant in the municipio of Salinas in southern Puerto Rico. To ensure that the geologic conditions along the possible routes do not represent a threat to the physical integrity of the natural gas pipeline, and thus comply with State and Federal regulations, the Puerto Rico Electrical Power Authority requested the U.S. Geological Survey to provide a synthesis of published literature of the geology of the coastal plain in the Peñuelas to Salinas area. The study area is located in part of the Southern Coastal Plain of Puerto Rico. In the area that extends from the municipio of Peñuelas eastward to the Laguna de las Salinas at Ponce, a distance of about 5 miles, the study area is underlain by middle Tertiary carbonate units. Eastward from the Laguna de las Salinas to the pipeline terminus at the Aguirre power plant in Salinas, a distance of about 30 miles, the terrain is underlain by fan-delta deposits of Quaternary age. The carbonate units and the fan-delta deposits are underlain by early Tertiary and older-age volcaniclastics with subordinate sedimentary rocks and lavas. The Great Southern Puerto Rico Fault Zone is the principal geologic structural feature in southern Puerto Rico. At present, the Great Southern Puerto Rico Fault Zone is considered largely quiescent, although it apparently is associated with minor earthquakes. There is no evidence of terrestrial, late Quaternary faulting within the Peñuelas to Salinas area. Seismic activity in this area mostly originates from extension zones of more distal shallow sources such as Mona Canyon to the northwest and the Anegada Trough northeast of the island of Puerto Rico. The magnitude of completeness of earthquakes in the study area ranges from 2.0 to 2.5. The seismic density for the southern coast including the study area is about 0.128 earthquakes per square mile, which is close to the average for southwestern Puerto Rico. The estimated maximum peak ground acceleration most likely to occur in the study area, due to shallow depth seismicity with 2 percent probability of exceedance in 50 years, is 9 feet per second squared, as obtained by modeling results. The estimated peak ground acceleration with 2 percent probability of exceedance in 50 years, due to deep seismicity is 7 feet per second squared. In Ponce, the probability of exceedance per year is higher than 0.1 for the peak ground acceleration values less than 1 that result from shallow depth seismicity sources such as the Mona Passage extension zone. The potential for liquefaction due to seismic activity may exist in areas near the coastline that have loosely to poorly consolidated sedimentary deposits and a water table close to or at the land surface. Slope failure susceptibility within the study area, due to rainfall and seismic activity, may be limited to the area that extends westward from Laguna de las Salinas to Peñuelas. In this area, foothills with slopes exceeding 10 degrees are close to the coastline and are underlain by clayey limestone and marls. In the remaining part of the study area, eastward from Laguna de las Salinas to Salinas, the land is either nearly flat or has a slope of less than 10 degrees; consequently, the susceptibility to landsliding (slope failure) caused by seismic activity and rainfall is considered to be minimal or nonexistent. Based on modeling results from a previous study, the estimated maximum inland extent of tsunami-induced flooding is 2,600 feet in the Laguna de las Salinas and Boca Chica, located in Ponce and Juana Díaz, respectively. Flooding about 3,000 and 2,800 feet from the coastline are estimated for areas near Punta Cabullón and Jobos areas, respectively. According to the modeling results, the estimated maximum runup of the tsunami-induced flooding ranges from 9 to 14 feet for the Boca Chica and Punta Cabullón areas, respectively.

Puerto Rico↗
USGS2009

Deep Resistivity Structure of Mid Valley, Nevada Test Site, Nevada

The U.S. Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) at their Nevada Site Office (NSO) are addressing ground-water contamination resulting from historical underground nuclear testing through the Environmental Management (EM) program and, in particular, the Underground Test Area (UGTA) project. From 1951 to 1992, 828 underground nuclear tests were conducted at the Nevada Test Site northwest of Las Vegas (DOE UGTA, 2003). Most of these tests were conducted hundreds of feet above the ground-water table; however, more than 200 of the tests were near, or within, the water table. This underground testing was limited to specific areas of the Nevada Test Site including Pahute Mesa, Rainier Mesa/Shoshone Mountain (RM-SM), Frenchman Flat, and Yucca Flat. One issue of concern is the nature of the somewhat poorly constrained pre-Tertiary geology and its effects on ground-water flow in the area subsequent to a nuclear test. Ground-water modelers would like to know more about the hydrostratigraphy and geologic structure to support a hydrostratigraphic framework model that is under development for the Rainier Mesa/Shoshone Mountain (RM-SM) Corrective Action Unit (CAU) (National Security Technologies, 2007). During 2003, the U.S. Geological Survey (USGS), in cooperation with the DOE and NNSA-NSO collected and processed data at the Nevada Test Site in and near Yucca Flat (YF) to help define the character, thickness, and lateral extent of the pre-Tertiary confining units. We collected 51 magnetotelluric (MT) and audio-magnetotelluric (AMT) stations for that research (Williams and others, 2005a, 2005b, 2005c, 2005d, 2005e, and 2005f). In early 2005 we extended that research with 26 additional MT data stations (Williams and others, 2006) located on and near Rainier Mesa and Shoshone Mountain (RM-SM). The new stations extended the area of the hydrogeologic study previously conducted in Yucca Flat, further refining what is known about the pre-Tertiary confining units. In particular, a major goal was to define the extent of the upper clastic confining unit (UCCU). The UCCU is composed of late Devonian to Mississippian siliciclastic rocks assigned to the Eleana Formation and Chainman Shale (National Security Technologies, 2007). The UCCU underlies the Yucca Flat area and extends southwestward toward Shoshone Mountain, westward toward Buckboard Mesa, and northwestward toward Rainier Mesa. Late in 2005 we collected data at an additional 14 MT stations in Mid Valley, CP Hills, and northern Yucca Flat. That work was done to better determine the extent and thickness of the UCCU near the boundary between the southeastern RM-SM CAU and the southwestern YF CAU, and also in the northern YF CAU. The MT data have been released in a separate U.S. Geological Survey report (Williams and others, 2007). The Nevada Test Site magnetotelluric data interpretation presented in this report includes the results of detailed two-dimensional (2-D) resistivity modeling for each profile and inferences on the three-dimensional (3-D) character of the geology within the region.

Nevada↗
USGS2010

Spatial and stage-structured population model of the American crocodile for comparison of comprehensive Everglades Restoration Plan (CERP) alternatives

As part of the U.S. Geological Survey Priority Ecosystems Science (PES) initiative to provide the ecological science required during Everglades restoration, we have integrated current regional hydrologic models with American crocodile (Crocodylus acutus) research and monitoring data to create a model that assesses the potential impact of Comprehensive Everglades Restoration Plan (CERP) efforts on the American crocodile. A list of indicators was created by the Restoration Coordination and Verification (RECOVER) component of CERP to help determine the success of interim restoration goals. The American crocodile was established as an indicator of the ecological condition of mangrove estuaries due to its reliance upon estuarine environments characterized by low salinity and adequate freshwater inflow. To gain a better understanding of the potential impact of CERP restoration efforts on the American crocodile, a spatially explicit crocodile population model has been created that has the ability to simulate the response of crocodiles to various management strategies for the South Florida ecosystem. The crocodile model uses output from the Tides and Inflows in the Mangroves of the Everglades (TIME) model, an application of the Flow and Transport in a Linked Overland/Aquifer Density Dependent System (FTLOADDS) simulator. TIME has the capability to link to the South Florida Water Management Model (SFWMM), which is the primary regional tool used to assess CERP restoration scenarios. A crocodile habitat suitability index and spatial parameter maps that reflect salinity, water depth, habitat, and nesting locations are used as driving functions to construct crocodile finite rate of increase maps under different management scenarios. Local stage-structured models are integrated with a spatial landscape grid to display crocodile movement behavior in response to changing environmental conditions. Restoration efforts are expected to affect salinity levels throughout the habitat of the American crocodile. This modeling effort examines how CERP restoration alternatives will affect growth and survival rates of hatchling and juvenile crocodiles, hatchling dispersal to suitable nursery habitat, and relative abundance and distribution in response to changing salinity and water depth for all stage classes of crocodiles. The response of the American crocodile to restoration efforts will provide a quantifiable measure of restoration success. By applying the crocodile model to proposed restoration alternatives and predicting population responses, we can choose alternatives that approximate historical conditions, enhance habitat for multiple species, and identify future research needs.

Open-File Report↗