Publisher: U.S. Geological Survey, Coastal and Marine Geology Program
Larger_Work_Citation:
Citation_Information:
Originator: David Twichell
Originator: Roman N. Zajac
Originator: Lawrence J. Poppe
Originator: Ralph S. Lewis
Originator: VeeAnn A. Cross
Originator: David R. Nichols
Originator: Mary L. DiGiacomo-Cohen
Publication_Date: 1998
Title:
Sidescan sonar image, surficial geologic interpretation, and bathymetry of the Long Island Sound sea floor off Milford, Connecticut
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: Geologic Investigations Series Map
Issue_Identification: I-2632
Publication_Information:
Publication_Place: Woods Hole, MA
Publisher: U.S. Geological Survey, Coastal and Marine Geology Program
Description:
Abstract:
Because of the enormous surrounding population of
Long Island Sound, large inputs of anthropogenic
wastes (e.g. fertilizers and sewage) and toxic
chemicals have produced stresses on the environment
of the Sound, causing degradation and potential loss
of benthic habitats. To examine this problem, we
completed a surficial geologic map of the western
Long Island Sound sea floor off Milford, Ct, in an
effort to define benthic habitats and how they are
changing with time.
This study was part of an interdisciplinary program
to define the surficial geology and benthic habitat
in Long Island Sound and to see how they are
changing with time.
Purpose:
This dataset presents the completed sidescan sonar
mosaic for the Milford, Connecticut study area.
Supplemental_Information:
The sidescan sonar mosaic reveals ten distinctive
sea-floor patterns, and when combined with the seismic
data can be used to make inferences about the surficial
geology. The ten patterns include
(1) low acoustic
backscatter (dark tones),
(2) high acoustic backscatter
(light tones),
(3) gas-charged sediment,
(4) fields of
positive relief high-backscatter targets interpreted
to be clusters of boulders,
(5) isolated high-backscatter
targets interpreted to be individual boulders,
(6) broad
curvilinear low-backscatter stripes inferred to be
bedforms,
(7) circular depressions with high-backscatter
floors,
(8) short, linear high-backscatter stripes,
(9) shallow, linear depressions interpreted to be trawl
marks, and
(10) long, thin, linear high-backscatter stripes
interpreted to be pipelines and cables. Boat wakes are
a water column phenomenon that were observed as well.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19931107
Ending_Date: 19931111
Currentness_Reference: Ground Condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -073.104167
East_Bounding_Coordinate: -073.029169
North_Bounding_Coordinate: +41.116667
South_Bounding_Coordinate: +41.033334
Keywords:
Theme:
Theme_Keyword_Thesaurus: General
Theme_Keyword: USGS
Theme_Keyword: U.S. Geological Survey
Theme_Keyword: Coastal and Marine Geology Program
Theme_Keyword: Long Island Sound Research Center
Theme_Keyword: Connecticut Geological and Natural History Survey
Theme_Keyword: sidescan sonar
Theme_Keyword: estuary
Theme_Keyword: benthic habitat
Theme_Keyword: hypoxia
Theme_Keyword: sediment distribution
Theme_Keyword: benthic community
Theme_Keyword: surficial geology
Place:
Place_Keyword_Thesaurus: General
Place_Keyword: Long Island Sound
Place_Keyword: Connecticut
Place_Keyword: Milford
Place_Keyword: estuary
Place_Keyword: Western Long Island Sound
Access_Constraints: None
Use_Constraints:
The U.S. Geological Survey must be referenced as the
originator of the dataset in any future products or
research derived from these data.
Although this derived data set and it's lineage dataset
have been used by the USGS, no warranty, expressed
or implied, is made by the USGS as to the accuracy
of the data and/or related materials. The act of
distribution shall not constitute any such warranty,
and no responsibility is assumed by the USGS in the use
of these data or related materials.
This sidescan sonar data were collected using a 100-kHz
Klein sidescan sonar system set to a 100-m range to either
side of the ship's track. These data were logged digitally
on a QMIPS data logger, and were written to 8mm tape.
Type_of_Source_Media: cartridge tape
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19931107
Ending_Date: 19931111
Source_Currentness_Reference: Ground Condition
Source_Citation_Abbreviation: QMIPS
Source_Contribution:
These data were processed to apply radiometric and
geometric corrections. The processed swaths were
then mapped and digitally mosaicked to complete
the sidescan sonar mosaic for the study area.
Process_Step:
Process_Description:
QMIPS data were processed through a median
filtering routine to suppress speckle noise.
Navigation merged into the header record portion
of the data were plotted and checked. The QMIPS
data were exported for import to the WHIPS
processing.
The individual sidescan swaths were processed
to apply a slant-to-ground range correction,
shading correction and striped noise removal.
the geometrically and radiometrically enhanced
swaths were then individually mapped to a user
specified scale and projection.
The individually mapped swaths were imported
into a PCI "pix" database file for digital
mosaicking. The mosaicking procedure included
trimming off unwanted data where two sonar images
overlapped, tone matching the adjacent sonar
images if there are differences, and combining
the individual strips together into a
composite image.
Utilizing the PCI Remote Sensing Software
reprojection utility, the completed and
archived mosaic was reprojected to UTM to
be consistent with current Long Island
Sound GIS datasets.
Although this derived data set and it's lineage
dataset have been used by the USGS, no warranty,
expressed or implied, is made by the USGS as to
the accuracy of the data and/or related materials.
The act of distribution shall not constitute any such
warranty, and no responsibility is assumed by the USGS
in the use of these data or related materials.
The sidescan sonar mosaic is available as a
GEOTIFF image with accompanying world file and
georeference report. To utilize this data, the user
must have an image viewer, image processing or
GIS software package capable of importing a
GEOTIFF image. If the georeferencing information
cannot be imported, the user may wish to obtain
the georeference information contained in a separate
file, georep.txt, included in the zip file.
