2005031814322400FALSE20050512174944002005051217502600{B90495E4-A14E-49F3-AD4B-8EC0D57155BA}Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.0.0.535enPulley Ridge is a series of drowned barrier islands that extends almost 200 km in 60-100 m water depths. This drowned ridge is located on the Florida Platform in the southeastern Gulf of Mexico about 250 km west of Cape Sable, Florida. This barrier island chain formed during the initial stage of the Holocene marine transgression. These islands were then submerged and left abandoned near the outer edge of the Florida Platform. The southern portion of Pulley Ridge hosts zooxanthellate scleractinian corals, green, red and brown macro algae, and a mix of deep and typically shallow-water tropical fishes. This reef community is in unusually deep water, and its extent and the controls on its distribution were unknown. To address these questions scientists from the U.S. Geological Survey Coastal and Marine Geology Program in cooperation with scientists from the University of South Florida Department of Marine Sciences have completed a detailed mapping of the southernmost 35 km of Pulley Ridge. The area was mapped using multibeam bathymetry, sidescan-sonar imagery, and high-resolution seismic-reflection profiling to define the geologic framework on which the reef is established. Submersible dives, remotely operated vehicle (ROV) transects, and transects of bottom photographs and video were collected to identify the corals and to map their distribution. This extensive suite of data has been compiled and preliminary analysis of the data suggests that the reefs are not tied to the ridge system, but instead are more broadly distributed. Whether reef distribution is controlled by oceanographic conditions or by subtle differences in the substrate that overlies the barrier island system is unclear, and are topics of continued research.Polygon shapefile indicating the interpretation of the sidescan-sonar mosaic.David C. Twichell2005Interpretation of the Surficial Geology in the Pulley Ridge Study Areapulley_interpvector digital dataVeeAnn A. CrossDavid C. TwichellRobert B. HalleyKate T. Ciembronowiczhttp://pubs.usgs.gov/of/2005/10892005GIS Compilation of Data Collected from the Pulley Ridge Deep Coral Reef RegionOpen-File Report2005-1089Woods Hole Science Center, Woods Hole, MAU.S. Geological Survey, Coastal and Marine Geology ProgramBret D. JarrettErika S. Hammar-KloseAl C. HineStan D. LockerDave F. Naarhttp://pubs.usgs.gov/of/2005/1089/data/interpretation/pulley_interp.zippublication date2004None planned-83.768420-83.59951324.99603524.665195-83.768420-83.59951324.66519524.996035GeneralFloridaFlorida ShelfGulf of MexicoNorth AmericaPulley RidgeUnited StatesGeneralCMGPCoastal and Marine Geology Programcoralcoral reefgeologic mapgeologyOF 2005-1089Open-File ReportpolygonshapefileU.S. Geological SurveyUSGSWoods Hole Science CenterNone.The U.S. Geological Survey must be referenced as the originator of the dataset in any future products or research derived from these data. ShapefileDavid C. TwichellU.S. Geological SurveyOceanographermailing and physical address384 Woods Hole Rd.Woods HoleMA02543-1598(508) 548-8700 x2266(508) 457-2310dtwichell@usgs.govMicrosoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.0.0.535pulley_interp-83.76842-83.59951324.99603524.6651951-83.76842-83.59951324.99603524.6651951enFGDC Content Standards for Digital Geospatial MetadataFGDC-STD-001-1998local timeVeeAnn A. CrossU.S. Geological SurveyMarine Geologistmailing and physical address384 Woods Hole Rd.Woods HoleMA02543-1598(508) 548-8700 x2251(508) 457-2310vatnipp@usgs.gov20050512http://www.esri.com/metadata/esriprof80.htmlESRI Metadata ProfileISO 19115 Geographic Information - MetadataDIS_ESRI1.0datasetDownloadable Data0.0400.040ShapefileDavid C. TwichellU.S. Geological SurveyOceanographermailing and physical address384 Woods Hole Rd.Woods HoleMA02543-1598(508) 548-8700 x2266(508) 457-2310dtwichell@usgs.govThese data were prepared by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Although all data published in this report have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and/or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials.002file://\\VEECRODTXP\Projects\reefs\gis\interpretation\pulley_interp.shpLocal Area Network0.040ShapefileVectorSimplePolygonFALSE41FALSEFALSEG-polygon41GCS_North_American_1983Decimal degrees0.0000000.000000North American Datum of 1983Geodetic Reference System 806378137.000000298.257222GCS_North_American_198341pulley_interpFeature Class41FIDFIDOID400Internal feature number.ESRISequential unique whole numbers that are automatically generated.ShapeShapeGeometry000Feature geometry.ESRICoordinates defining the features.IDIDNumber8Computer generated polygon ID number.Software.0INTERPINTERPString16Interpretation of the seafloor based on the sidescan-sonar mosaic.Scientist - David C. Twichellcharacter setThe Interp attribute definitions are as follows:
terraces: Alternating linear bands of high and low backscatter on the sidescan-sonar imagery. The high-backscatter stripes are interpreted to be reflections off rock surfaces while the low-backscatter stripes are either shadows cast by the terraces or areas where fine-grained sediment has covered parts of the terraces. The bathymetry shows that the terraces occur along the flanks of the narrow ridge that marks the crest of the ridge. Video observations show outcrops of hardgrounds in these areas.
high-backscatter: The sidescan-sonar images were smoothed in PCI with a 7x7 average filter, and the areas with values mostly between 117 and 225 were mapped as areas of high backscatter. video observations indicate that these areas are a mix of exposed hardgrounds, carbonate rubble, and deep-water coral.
broad lines: The sidescan sonar image shows subtle variations in backscatter intensity that coincide with low-relief ridges on the multibeam bathymetry.
depression-large: Sub-circular depressions show on the multibeam bathymetry that have 30-200 m diameters and are less than 3 m deeper than the surrounding seafloor. Many of these depressions have low-backscatter floors on the sidescan-sonar imagery. Video observations indicate that the floors of these depressions are fine sand.
mottled-mod: The sidescan-sonar image shows a mottled seafloor of moderate and low-backscatter patches that have dimensions of 50-200 m. The average backscatter values on the filtered image for these areas are mostly 110-120.
mod-backscatter: More uniform in backscatter intensity than the mottled-moderate backscatter regions. These areas occur mostly around the edges of the ridge where the seafloor is smoother than it is on the ridge itself. Video observations from these areas show a sandy seafloor with some carbonate cobbles, but the cobbles are not as concentrated as they are on the ridge.
mottled-low: Low backscatter areas that are interrupted by sub-circular moderate backscatter patches that are 20-100 m in diameter. The moderate backscatter patches commonly have a pit or mound near their centers. The background in these areas mostly has a DN value less than 100. The multibeam bathymetry shows that the seafloor in these areas is smooth, and video observations indicate that the seafloor is somewhat sandier than other parts of the study area.
low-backscatter: Areas with a smooth seafloor with a low-backscatter (DN less than 105) appearance. the only part of the study area with this appearance is in the southernmost part of the area beyond the shelf on the uppermost slope.20050512Sidescan-sonar image mosaics were enhanced within PCI Geomatics software, using a linear stretch mapping the values between 80 and 140 across the entire 8-bit range (0-255). In addition, a 7x7 average filter was applied to smooth the images.