Processed Continuous Resistivity Profiles from Cape Cod National Seashore, May 19, 2004

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How should this data set be cited?

   Bratton, John F. , 2008, Processed Continuous Resistivity Profiles from Cape Cod National Seashore, May 19, 2004: Open-File Report 2006-1169, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

   Online Links:

   • <http://pubs.usgs.gov/of/2006/1169/data/res_data/2004/proc_resis/may19_proc.zip>
   • <http://pubs.usgs.gov/of/2006/1169/htmldocs/catalog.htm>

   This is part of the following larger work.

   Cross, VeeAnn A. , Bratton, John F. , Crusius, John, Colman, John A. , and McCobb, Timothy D. , 2008, Submarine Hydrogeological Data from Cape Cod National Seashore: Open-File Report 2006-1169, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

   Online Links:

   • <http://pubs.usgs.gov/of/2006/1169/>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -69.991417

   East_Bounding_Coordinate: -69.919617

   North_Bounding_Coordinate: 41.756183

   South_Bounding_Coordinate: 41.669400

3. What does it look like?

4. Does the data set describe conditions during a particular time period?

   Calendar_Date: 19-May-2004

   Currentness_Reference: ground condition

5. What is the general form of this data set?

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?

   2. What coordinate system is used to represent geographic features?

7. How does the data set describe geographic features?

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • John F. Bratton

2. Who also contributed to the data set?

3. To whom should users address questions about the data?
   John F. Bratton
   U.S. Geological Survey
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   508-548-8700 x2254 (voice)
   508-457-2210 (FAX)
   jbratton@usgs.gov
   

Why was the data set created?

To provide resistivity data as collected by the AGI SuperSting system and processed with EarthImager software.

How was the data set created?

1. From what previous works were the data drawn?

   (source 1 of 1)

   Source_Contribution:

   These data were acquired with an AGI SuperSting Marine system that is described at the website: www.agiusa.com/marinesystem.shtml. The particular system used for this acquisition was an 11 stainless steel electrode array with electrodes spaced 10 meters apart. A dipole-dipole configuration was used for the data collection in which two fixed current electrodes are assigned with the measurement of voltage potentials between electrode pairs in the remaining electrodes. Each line of data acquisition records several files. The two files necessary for processing are the *.stg and *.gps file. The STG file contains the resistivity data, while the GPS file contains the navigation information. Bathymetry point data was collected with a separate system and logged as text files.

2. How were the data generated, processed, and modified?

   Date: 2004 (process 1 of 11)

   The data were transferred from the logging computer via AGISSAdmin software. The data files available for this day are chatham7*, chatham8*, chatham9*, chatha10*, chatha11*, chatha12*, chatha13*, chatha14*, chatha15*, chatha16*, chatha17*, and chatha18*.

   Person who carried out this activity:
   

   John F. Bratton
   U.S. Geological Survey
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2254 (voice)
   (508) 457-2310 (FAX)
   jbratton@usgs.gov
   

   Date: 2004 (process 2 of 11)

   The bathymetry text files needed to be merged with the GPS navigation files. The logging of the navigation files started at the same time as the logging of the resistivity files. Although the bathymetry data contains no time stamps, the assumption was made that the time span was the same as the navigation file. The bathymetry data was acquired in feet at a faster rate than the navigation data. An awk script was written to convert the bathymetry data to meters, pull the appropriate bathymetry point to match up with the navigation point, and output the format as SDDBT (the format that EarthImager expects). The points to pull was based on the assumption that the time span of navigation and bathymetry was the same, so took the total number of bathymetry points and divided it by the number of navigational fixes, and pulled the bathymetry point at that increment. Another awk script was written to merge the navigation data and bathymetry data into a single file.

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 3 of 11)

   $GPRMC lines with the GPS file that had bad time stamps or were otherwise corrupt were deleted.

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 4 of 11)

   The resistivity data were merged with the navigation data and linearized using AGI's Marine Log Manager software. (Note that the Marine Log Manager version is different than the software version of the AGISSAdmin software of which it is a part - although shipped together, the software is developed separately). In some instances, only a portion of the line was exported for processing. In particular, turns are removed before processing.

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 5 of 11)

   The file was then exported to a new STG file, and accompanying DEP file. The DEP file contains the distance along line and bathymetry values.

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 6 of 11)

   The DEP file was checked for anomalous bathymetry values, or duplicated distance along values, and those lines in the file were deleted.

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 7 of 11)

   EarthImager software does not require that a default resistivity value for the water column be supplied in the DEP file. If one is not supplied, then it calculates a value based on the first electrode pair. No instrument was available to measure the water resistivity, so this value was left blank.

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 8 of 11)

   EarthImager version 1.7.8 was used to process the data files. The *.ini file accompanying the results contains the parameters used during the processing. These parameters include: minimum voltage: 0.02; minimum abs(V/I): 2E-5; max repeat error: 3%; min apparent res: 0.03; max apparent res: 1000; max reciprocal error: 5%; remove spikes, robust model inversion; finite difference method; Cholesky decomposition; Dirichlet boundary condition; thickness incremental factor: 1.1; depth factor: 1.1; number of iterations: 8; stop criteria: max RMS 3%; error reduction 6%; L2Norm; CRP processing using a 65% overlap

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 9 of 11)

   The results of the processing are JPEG images of the resistivity profile (a short and extended version), and an XYZ file containing the distance along, depth, apparent resistivity (ohm-m). The JPEG files produced use a color scale that is based on the data from that particular file.

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 10 of 11)

   The XYZ output file was then loaded into Matlab, along with the depth information, to create a new JPEG image with the same color scale for all the data files. In this manner, the JPEG images can be compared directly. Care was taken to try to get the vertical and horizontal scales uniform as well, although this was not always possible due to Matlab limitations. These images reside in the "matlabimages" folder.

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

   Date: 2004 (process 11 of 11)

   The XYZ output file was also loaded into Matlab with the DEP file so that those resistivity values in the water column could be removed. The extrapolated value at the sediment water interface was exported, as well as all the values in the original XYZ file below the DEP line. These new XYZ files are in the folder "trimxyz".

   Person who carried out this activity:
   

   VeeAnn A. Cross
   U.S. Geological Survey
   Marine Geologist
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2251 (voice)
   (508) 457-2310 (FAX)
   vatnipp@usgs.gov
   

3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?

2. How accurate are the geographic locations?

3. How accurate are the heights or depths?

4. Where are the gaps in the data? What is missing?

   All resistivity data collected on this particular day was considered valid and represented here.

5. How consistent are the relationships among the observations, including topology?

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

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.

1. Who distributes the data set? (Distributor 1 of 1)
   John F. Bratton
   U.S. Geological Survey
   384 Woods Hole Rd.
   Woods Hole, MA 02543-1598
   

   (508) 548-8700 x2254 (voice)
   (508) 457-2310 (FAX)
   jbratton@usgs.gov
   

2. What's the catalog number I need to order this data set?

   Downloadable Data

3. What legal disclaimers am I supposed to read?

   Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. 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. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	AGI Size: 13.6

   • Cost to order the data: None.

5. What hardware or software do I need in order to use the data set?

   These data are available in a format compatible with AGI Geosciences EarthImager software, as well as summary images in JPEG format. The user must have software capable of reading the AGI format, or software capable of viewing JPEG images.

Who wrote the metadata?

Dates:

Last modified: 25-Feb-2008

Metadata author:

VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA 02543-1598

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov

Metadata standard:

FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

Metadata extensions used:

• <http://www.esri.com/metadata/esriprof80.html>