Shaded Relief Map

Most of California's natural oil and gas seeps are in the area circled in white on this shaded relief map. The state's major underground oil and gas fields (known from drilled wells) are in the three areas outlined in yellow. Note that the seeps occur near the oil and gas oil fields. This is no coincidence.

The reason seeps are found close to major oil and gas fields is that most seeps are fed by these natural underground reservoirs. Just as springs are fed by underground reservoirs of water, oil and gas seeps are fed by underground reservoirs of oil and gas.

The low area, colored dark green, is the Central Valley, California's famous agricultural belt. It is underlain by sedimentary rocks that are rich in petroleum and is home to the state's largest oil and gas fields. Oil and gas migrate upward from these underground fields to form the adjacent oil and gas seeps. Click on the "Seeps Index" button or the "Fields Index" button to view a more detailed map of seeps or fields.

URL: http://seeps.wr.usgs.gov/seeps/where.html
Maintained by fcole@octopus.wr.usgs.gov
Last updated 6/25/99