communities are associated with the vents. Though the vents themselves are not composed of serpentinite, they are hosted in serpentinite estimated to have formed at a temperature of about . Sepiolite deposits on mid-ocean ridges may have formed through serpentinite-driven hydrothermal activity. However, geologists continue to debate whether serpentinization alone can account for the heat flux from the Lost City field. The forearc of the Marianas subduction zone hosts large serpentinite mud volcanoes, which erupt serpentinite mud that rises through faults from the underlying serpentinized forearc mantle. Study of these mud volcanoes gives insights into subduction processes, and the high pH fluids emitted at the volcanoes support a microbial community. Serpentinite thermal vents are a candidate for the environment in which life on Earth originated. Most of the chemical reactions necessary to synthesize acetyl-CoA, essential to basic biochemical pathways of life, take place during serpentinization. The sulfide-metal clusters that activate many enzymes resemble sulfide minerals formed during serpentinization. Experimental drilling into the gabbro layer of oceanic crust near mid-ocean ridges has demonstrated the presence of a sparse population of hydrocarbon-degrading bacteria. These may feed on hydrocarbons produced by serpentinization of the underlying ultramafic rock. Ecology Soil cover over serpentinite bedrock tends to be thin or absent. Soil with serpentine is poor in calcium and other major plant nutrients, but rich in elements toxic to plants such as chromium and nickel. Some species of plants, such as Clarkia franciscana and certain species of manzanita, are adapted to living on serpentinite outcrops. However, because serpentinite outcrops are few and isolated, their plant communities are ecological islands and these distinctive species are often highly endangered. On the other hand, plant communities adapted to living on the serpentine outcrops of New Caledonia resist displacement by introduced species that are poorly adapted to this environment. Serpentine soils are widely distributed on Earth, in part mirroring the distribution of ophiolites and other serpentine bearing rocks. There are outcroppings of serpentine soils in the Balkan Peninsula, Turkey, the island of Cyprus, the Alps, Cuba, and New Caledonia. In North America, serpentine soils also are present in small but widely distributed areas on the eastern slope of the Appalachian Mountains in the eastern United States, and in the Pacific Ranges of Oregon and California. Occurrences Notable occurrences of serpentinite are found at Thetford Mines, Quebec; Lake Valhalla, New Jersey; Gila County, Arizona; Lizard complex, Lizard Point, Cornwall; and