Asphalt volcanoes form where oil rises through faults in the Earth’s crust and escapes onto the ocean floor. As its lighter components disperse, the thick petroleum left behind spreads and hardens into folds and domes resembling lava. Unknown to science until 2003, examples in the Gulf of Mexico lie around 3,000 metres underwater; others off California are larger than a football field. They are oil deposits that have built their own mountains.
Asphalt volcanoes
