La Brea Pitch Lake

It is the world's largest natural reservoir of asphalt. However, commercial excavation of asphalt has slowed down considerably, since other more cost effective materials are available for road construction. The pitch lake is now primarily a tourist destination. Many go to bathe in its waters, which contain sulphur, which some say has healing properties. As the picture shows, bitumen wells up from deep underground. Once on the surface some of the lighter hydrocarbons evaporate into the air, leaving the bitumen behind. This hardens to a crust that can be walked on and even driven on. In some places, as the picture shows the softer viscous tar beneath breaks the surface. There is an Amerindian legend that a village chieftain killed a humming bird and his village was swamped by the pitch lake in revenge. It may even be at least partly true. A fault in the earth may have started to leak petroleum within human history. In that case the welling up of the petroleum from within the rocks could easily have overwhelmed a village in the hills. The methane gas may have asphyxiated them first and then the slowly welling pitch gone on to engulf their village. A challenge for archaeologists. If they are there they would probably be well preserved.