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6.25: Sedimentary Rock Formations

  • Page ID
    10247
    • Contributed by Miracosta Oceanography 101
    • Sourced from Miracosta)

    Sedimentary Rock Formations

    A rock formation is the primary unit of stratigraphy, consisting of a succession of strata useful for mapping or description. A rock formation typical consists of a unique lithology (rock type) that has a relatively defined geologic age and is considered mappable (occurs throughout area or region, both on the surface and in the subsurface. Rock formations can be of igneous, sedimentary, or metamorphic origin. Sedimentary rock formations preserve information (including fossils and sedimentary structures) about the sedimentary environments they formed in. Figures 6-87 to 6-89 are examples of marine sedimentary rock formations.

    Delmar Dog Beach Santa Cruz Mudstone at Wilder Ranch State Park ribbon chert, Marin Headlands, California
    Figure 6.87. Ancient beach, bay, and coastal dune deposits exposed in rock formations at the Del Mar Dog Beach, San Diego County, California Figure 6.88. Ancient continental shelf deposits preserved in the Santa Cruz Mudstone Formation (Miocene-Pliocene age) in Santa Cruz, CA Figure 6.89. Ancient deep ocean siliceous ooze deposits preserved as ribbon chert in the Franciscan Formation (Jurassic age), Santa Cruz Mountains, CA