Any spurious data points were removed during processing. For each seismic trackline there is one seismic-profile image. No duplicates exist.
Lines were serially recorded during the survey in the format "LXF1". When a file is named "LXF2" or has a file number greater than 2, the recording parameters were usually changed (record length and shot rate), as recorded in the ship's log. The following lines were either not recorded or excluded from this data release: L82F1, L87F1, L99F1, L115F1, L142F1 (all excluded due to negligible length).
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: Unpublished Material
Title: raw seismic navigation
Type_of_Source_Media: Information unavailable from original metadata.
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20120525
Beginning_Time: 0937 (UTC)
Ending_Date: 20120527
Ending_Time: 0715 (UTC)
Source_Currentness_Reference: ground condition of survey on dates 20120525-20120527
Source_Citation_Abbreviation: Information unavailable from original metadata.
Source_Contribution:
Seismic-reflection data acquisition: Chirp seismic data were collected using an EdgeTech SB-0512i towfish (0.5-4.5 kHz pulse, 50 ms pulse length), which was towed astern of the M/V Tiki XIV of Ocean City, MD. Chesapeake Technologies' SonarWiz (v.4.04.0031) seismic acquisition software was used to control the chirp, digitally log trace data in the SEG-Y Rev. 1 format (IEEE floating point), and record GPS navigation coordinates to the SEG-Y trace headers (in arc seconds of Latitude and Longitude, multiplied by a scalar of 100). Trace lengths are constant within lines, but vary from line to line due to variable water depth in the survey area (the minimum trace length was 250 ms and the maximum 1400 ms). This yields a range of samples per trace from approximately 5435 (250 ms trace length) to 30435 (1400 ms trace length). Sample interval was kept at a constant .000046 s. The ping rate was set to be consistent with the trace length, so it varied between 250 ms and 1400 ms.
Process_Step:
Process_Description:
Seismic Unix (version 4.2) was used to read SEG-Y files, write a Seismic Unix file, and extract SEG-Y trace header information, including shot number, longitude, latitude, year, Julian day, and time of day (UTC). Header information from each SEG-Y file was saved to text files after an AWK (no version) filter was used to maintain shots at multiples of 100 and shots with unique navigation coordinates. End shots and shots at multiples of 100 may not have unique navigation coordinates. Separate text files containing unique shot navigation were also produced.
Process_Date: 201206
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jeffrey Obelcz
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x. 2245
Contact_Electronic_Mail_Address: jobelcz@usgs.gov
Process_Step:
Process_Description:
The 100 shot interval text files produced from process step 1 were concatenated into a comma-delimited text file, then the text file was imported into ArcMap (version 9.3) using 'Add XY data' and saved as points (Geographic, WGS84) in the Esri shapefile format.
Process_Date: 201305
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jeffrey Obelcz
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x. 2245
Contact_Electronic_Mail_Address: jobelcz@usgs.gov
Process_Step:
Process_Description:
The shapefile containing 100 shot interval positions, created in the previous step, was used as an input for VACExtras (version 3.1.2), a VB collection of tools developed by VeeAnn Cross (USGS-WHSC), which converts point data to a new polyline shapefile ('BC_tracklines.shp').. The 'line' field was used to define which points were used to generate each polyline feature, and the fields "lon " (line beginning longitude), "lat" (line beginning latitude), "jd_hour_mi" (line time start), "year" (year of data acquistion), "lon_end" (line ending longitude), "lat_end" (line ending latitude), and "jd_hou_end" (line ending time) were included as attributes in the output shapefile.
Process_Date: 201305
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Jeffrey Obelcz
Contact_Organization: U.S. Geological Survey
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x. 2245
Contact_Electronic_Mail_Address: jobelcz@coastal.edu
Process_Step:
Process_Description:
The attribute "hlink" was added to the shapefile in ArcMap 9.3.1 and populated with the relative path and seismic-reflection profile image filename corresponding to the trackline. This allows the user to "hotlink" to the seismic profiles from within ArcMap. In order for this to work, the user must activate the "Hyperlinks" option of the dataset properties display tab. The field to use is "hlink" and the link type is a document. In the ArcMap - File - Document properties the user needs to supply the hyperlink base This is the remainder of the file location path prior to the data folder indicated in the "hlink" attribute.
Process_Date: 201401
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: VeeAnn A. Cross
Contact_Organization: U.S. Geological Survey
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: Massachusetts
Postal_Code: 02543-1598
Country: USA
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Added the DOI link as the first link in the identification section. Updated the link to the field activity. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent.
Process_Date: 20171004
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description: USGS Thesaurus keywords added to the keyword section.
Process_Date: 20180720
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
Process_Step:
Process_Description:
Added keywords section with USGS persistent identifier as theme keyword.
Process_Date: 20200908
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: VeeAnn A. Cross
Contact_Position: Marine Geologist
Contact_Address:
Address_Type: Mailing and Physical
Address: 384 Woods Hole Road
City: Woods Hole
State_or_Province: MA
Postal_Code: 02543-1598
Contact_Voice_Telephone: 508-548-8700 x2251
Contact_Facsimile_Telephone: 508-457-2310
Contact_Electronic_Mail_Address: vatnipp@usgs.gov
