Cabrillo Beach Coastal Processes Trip

Salinas de San Pedro

Sediment Analysis

(click the image for a larger version)
Sample collected on Saturday, March 16, 2019. Mud is a mix of silt and clay - two grain sizes that can't be seen by the naked eye. This is a protected area so sampling is not allowed. The mud in the Salinas de San Pedro is comprised mostly of microscopic quartz and clay grains that are at most 0.064 mm in size (nearly all are considerably less).

Coastal Processes

The Salinas de San Pedro Saltmarsh was created in 1985 by the Port of Los Angeles. Located in Cabrillo Beach Park, it restores a part of the marsh enviroment lost during the last century of development. Note the water in the image below- do you see any waves? Coastal wetlands typically form as a river approaches the ocean. The water slows down and floods the surrounding area. In doing so, the sediment carried in the river is deposited, creating a flat, muddy region and reducing the amount of sediment entering the ocean. Wave energy in wetlands is extremely low; tides will cause the water level to raise and lower, but waves in general are mostly non-existant.

Cabrillo Beach Salt Marsh at high and low tide, Saturday, April 8, 2017.
Mouse over the image below to see what the saltmarsh looks like at high and low tides. Photo taken on Saturday, April 8, 2017.

The result is a shallow, quiet water environment that is perfect for the young of many aquatic species, providing them with a haven from larger predators. The water here has a lower salinity level than does the ocean, making it a perfect spot for many species to rest and have a drink of water and maybe a snack. In addition to numerous native plant species surounding it, the marsh is home to many bird species, such as blackcrowned night-herons, willets, great blue herons, snowy egrets (all year round inhabitants), sandpipers, killdeer and grebes (migratory visitors). Aquatic species include worms, clams, crabs, and other invertibrates, in addition to small fish. During high tide corbina, sharks and stingrays can be found.3

Raccoons and cats are a particular problem for the saltmarsh, as they can easily slip through the fence for a quick meal.














3. "Coastal Park." Cabrillo Marine Aquarium. Web. 15 May 2016. <>.