and Landslides Due to active erosion, seismic activity, and the loosely cemented nature of the local Colma and Merced formations, the area is an active landslide zone. During ENSO years, coastal erosion on the Merced and Colma formations can average up to 2 to 3 feet per year. In addition to erosion via tides and winds, movement along the San Andreas fault and Mussel Rock fault and construction along the clifftops contribute to erosion in the area, exacerbating the risk of landslides. Ecology Mussel Rock visitors can harvest mussels, but only during the approved season and with guidance from the California Department of Public Health. The California Department of Public Health regularly tests for paralytic shellfish poisoning and posts advisory information to its website. History ~1500 — 1776: Ompuromo Village The earliest recorded settlement at Mussel Rock was Ompuromo (ocean-flea place) inhabited by the Yelamu tribe of the Ohlone people. Based on carbon dating of archeological findings from a midden excavated at Mussel Rock, the village was estimated to date back to approximately 1500 AD, although Ohlone people are known to have inhabited the San Mateo area since at least 5,000 years ago, and lasted until Spanish colonization in 1776. In 1978, the midden was excavated and found to contain artifacts including debris from lithic tool manufacturing and faunal remains from food items. Unfortunately, only 45 cubic meters were excavated before Daly City began the construction of the garbage sorting facility, Mussel Rock Transfer Station, atop the midden. The adjacent area was used as a landfill from 1958 to 1978, preventing any other nearby archeological excavation. Gallery See also List of islands of California Notes References External links 1982-83 El Niño Mussel Rock Coastal Erosion Map - USGS Cliff Hangers: 17 houses on Daly City block sliding toward ocean plunge Environmental History of Mussel Rock Islands of the San Francisco Bay Area Islands of Northern California Stacks of the United States Geology of San Mateo County, California Islands of San Mateo County, California Rock formations of California Uninhabited islands of California Pacific islands of California Daly City, California