JPEG Images of Seismic-Reflection Profiles Collected in Lake Mead in 2001

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Frequently anticipated questions:

What does this data set describe?

Title:
JPEG Images of Seismic-Reflection Profiles Collected in Lake Mead in 2001
Abstract:
Lake Mead is a large interstate reservoir located in the Mojave Desert of southeastern Nevada and northwestern Arizona. It was impounded in 1935 by the construction of Hoover Dam and is one of a series of multi-purpose reservoirs on the Colorado River. The lake extends 183 km from the mouth of the Grand Canyon to Black Canyon, the site of Hoover Dam, and provides water for residential, commercial, industrial, recreational, and other non-agricultural users in communities across the southwestern United States. Extensive research has been conducted on Lake Mead, but a majority of the studies have involved determining levels of anthropogenic contaminants such as synthetic organic compounds, heavy metals and dissolved ions, furans/dioxins, and nutrient loading in lake water, sediment, and biota (Preissler, et al., 1998; Bevans et al, 1996; Bevans et al., 1998; Covay and Leiker, 1998; LaBounty and Horn, 1997; Paulson, 1981). By contrast, little work has focused on the sediments in the lake and the processes of deposition (Gould, 1951). To address these questions, sidescan-sonar imagery and high-resolution seismic-reflection profiles were collected throughout Lake Mead by the USGS in cooperation with researchers from University of Nevada Las Vegas (UNLV). These data allow a detailed mapping of the surficial geology and the distribution and thickness of sediment that has accumulated in the lake since the completion of Hoover Dam. Results indicate that the accumulation of post-impoundment sediment is primarily restricted to former river and stream beds that are now submerged below the lake while the margins of the lake appear to be devoid of post-impoundment sediment. The sediment cover along the original Colorado River bed is continuous and is typically greater than 10 m thick through much of its length. Sediment thickness in some areas exceeds 35 m while the smaller tributary valleys typically are filled with less than 4 m of sediment. Away from the river beds that are now covered with post-impoundment sediment, pre-impoundment alluvial deposits and rock outcrops are still exposed on the lake floor.
  1. How might this data set be cited?
    Cross, VeeAnn A., and Twichell, David C., 2003, JPEG Images of Seismic-Reflection Profiles Collected in Lake Mead in 2001: Open-File Report 02-478, U.S. Geological Survey, Coastal and Marine Geology Team, Woods Hole Field Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A., and Twichell, David C., 2003, Archive of Seismic-Reflection Data Collected During USGS Cruise Lake Mead 01007 in Lake Mead - Nevada and Arizona, 1-28 April, 2001: Open-File Report 02-478, U.S. Geological Survey, Coastal and Marine Geology Team, Woods Hole Field Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -114.7642
    East_Bounding_Coordinate: -114.0187
    North_Bounding_Coordinate: 36.4871
    South_Bounding_Coordinate: 36.0000
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 01-Apr-2001
    Ending_Date: 26-Apr-2001
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster
  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?
    Entity_and_Attribute_Overview:
    These images are intended only as previews of the seismic-reflection data. In each image, the x-axis represents shot point, the y-axis is two-way travel time in milliseconds. The scale bar along the bottom of the image is inaccurate due to a bug in the digital processing software and therefore should be ignored.
    Entity_and_Attribute_Detail_Citation:
    Not provided with original metadata; assumed to be the data processor.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • VeeAnn A. Cross
    • David C. Twichell
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    VeeAnn A. Cross
    USGS
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

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

Why was the data set created?

These images of the seismic-reflection profiles are provided so that individuals can preview the seismic data without the requirement of special software.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2001 (process 1 of 8)
    The seismic data collected in 2001 was actually of 2 types: chirp and boomer. The chirp data was collected as part of the SIS-1000 system, while the boomer data was logged onto a Triton Elics system. *The process date was added as a required element when the metadata was updated in 2026. The process date is an assumption based on the process step itself.
    Date: 2002 (process 2 of 8)
    The SEG-Y data was then loaded into Landmark software. *The process date was added as a required element when the metadata was updated in 2026. The process date is an assumption based on the process step itself.
    Date: 2002 (process 3 of 8)
    Metadata imported. *The process date was added as a required element when the metadata was updated in 2026. The process date is an assumption based on the process step itself. Data sources used in this process:
    • F:\LMSEGY\2001\segy\metadata.xml
    Date: 2002 (process 4 of 8)
    CGM images were created of each seismic profile. *The process date was added as a required element when the metadata was updated in 2026. The process date is an assumption based on the process step itself.
    Date: 2002 (process 5 of 8)
    These CGM images were converted to JPEGs using Larson software. *The process date was added as a required element when the metadata was updated in 2026. The process date is an assumption based on the process step itself.
    Date: 2002 (process 6 of 8)
    These jpegs were then downsampled to a GIF format. *The process date was added as a required element when the metadata was updated in 2026. The process date is an assumption based on the process step itself.
    Date: 2002 (process 7 of 8)
    These GIFS were then converted back to JPEGs. *The process date was added as a required element when the metadata was updated in 2026. The process date is an assumption based on the process step itself.
    Date: 01-Jun-2026 (process 8 of 8)
    This metadata file was updated as part of metadata maintenance when added to the web accessible folder. Edits were performed on the original text version of the metadata, then converted to XML. These edits included: Fixed all errors flagged by MP. These included (but are not limited to) adding required elements such as publication place when publisher is provided; added process dates. Additionally, added some DOI online links when possible; added supplemental information with link to the field activity; added USGS Thesaurus and ISO 19115 Topic Category thesauri and appropriate terms in each; renamed “General” thesauri to “None” thesauri; updated the use and access constraints to approved statements; updated the distribution liability to a current approved statement; added a digitale distribution format secion; added a geospatial presentation format; updated metadata email to a generic email in the event the person leaves the USGS (20260601) Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Bevans, H.E., Goodbred, S.L., Miesner, J.F., Watkins, S.A., Gross, T.S., Denslow, N.D., and Choeb, T., 1996, Synthetic organic compounds and carp endrocrinology and histology, Las Vegas Wash and Las Vegas and Callville bays of Lake Mead, Nevada: Water-Resources Investigations 96-4266, U.S.Geological Survey Water Resources, Reston, VA.

    Bevans, H.E., Lico, M.S., and Lawrence, S.J., 1998, Water quality in the Las Vegas Valley area and the Carson and Truckee River basins, Nevada and California, 1992-1996: Circular 1170, U.S. Geological Survey, Reston, VA.

    Online Links:

    Couvay, K.J., and Leiker, T.J., 1998, Synthetic organic compounds in water and bottom sediment from streams, detention basins, and sewage-treatment plant outfalls in Las Vegas Valley, Nevada, 1997: Open-File Report 98-633, U.S. Geological Survey, Reston, VA.

    Online Links:

    Gould, H.R., 1951, Some quantitative aspects of Lake Mead turbidity currents: SEPM Society for Sedimentary Geology Special Publication No. 2, SEPM Society for Sedimentary Geology, McLean, VA.

    Online Links:

    LaBounty, J.F., and Horn, M.J., 1997, The influence of drainage from the Las Vegas Valley on the limnology of Boulder Basin, Lake Mead, Arizona-Nevada: Journal of Lake and Reservoir Management v. 13, issue 2, Journal of Lake and Reservoir Management, London, England.

    Online Links:

    Paulson, L.J., 1981, Nutrient management with hydroelectric dams on the Colorado River: Technical Report #8, Lake Mead Limnological Research Center, Department of Biological Sciences, University of Nevada, Las Vegas, Nevada.

    Preissler, A.M., Roach, G.A., Thomas, K.A., and Wilson, J.W., 1998, Water resources data, Nevada, water year 1998: Water Resources Data Nevada NV-98-1, U.S. Geological Survey, Reston, VA.

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?
    These files represent images of all the seismic-reflection data collected in Lake Mead in 2001 by the USGS.
  5. How consistent are the relationships among the observations, including topology?
    Not available from the original metadata.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints No access constraints. Please see 'Distribution Information' for details.
Use_Constraints These data are marked with a Creative Commons CC0 1.0 Universal License. These data are in the public domain and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. 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)
    VeeAnn A. Cross
    USGS
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@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?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: JPEG Size: 14.1
      Media you can order: These data were released on DVD that is currently not available online. (format Not documented with the original metadata.)
    • Cost to order the data: None

Who wrote the metadata?

Dates:
Last modified: 02-Jun-2026
Metadata author:
VeeAnn A. Cross
USGS
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA

508-548-8700 x2251 (voice)
508-457-2310 (FAX)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the contact person is no longer with the USGS.
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2002-478/imagesmetadata.faq.html>
Generated by mp version 2.9.51 on Tue Jun 2 16:43:33 2026