A dark mass of churning natural asphalt at La Brea:
Objects placed on the surface vanish and reappear years
later as the pitch slowly swirls. The source is a fault line
in the sandstone 250-feet down, through which crude oil or
bitumen seeps, feeding an endlessly replenished pool of
bitumen for roads and mastic asphalt roofs. There is a small
museum and guides.