Madrona Marsh

The Madrona Marsh Preserve, in the city of Torrance in the South Bay region of Southern California, is a seasonal wetland with vernal pools.

The 43 acres (17 ha) was a former site of oil wells and is one of the few natural areas remaining within an urban landscape.

[1] Formed eons ago when the mountains of the Palos Verdes Peninsula rose to the south, Madrona Marsh is a shallow depression fed by wet season (spring) storms as the name "vernal" indicates.

After the rainy season, evaporation, percolation and transpiration reduce the water depth by about one-quarter of an inch (6 mm) per day.

[2] Situated on land that was set aside for oil production in 1924, Madrona Marsh was never developed while the city grew up around the site and remains a valuable natural habitat for birds, reptiles, insects and small mammals.