Pitch Lake is a lake you can walk out into the middle of: some 40 hectares of black asphalt, firm enough to carry your weight and reckoned about 76 metres deep at its churning centre. It is the largest natural asphalt deposit on Earth, and it lies where two faults cross beneath the town of La Brea. Crude oil rises along that fracture from a reservoir far below, the light fractions burn off in the tropical sun, and the heavy residue thickens into pitch. Walter Raleigh careened his ships with it in 1595 and noted that it "melteth not with the sunne as the pitch of Norway." Since the industry took hold in the 1880s the digging has never stopped. Trinidad asphalt surfaced Washington's Pennsylvania Avenue in 1876, and 140 years later it went into the deck of the Hong Kong-Zhuhai-Macau Bridge, the longest sea crossing in the world.
Out on the crust the ground is warm and faintly tacky, there is no shade anywhere, and the pitch ticks and creaks as it heats. Your guide walks ahead probing with a stick: roughly a quarter of the surface stays soft, and vehicles sink. Gas fizzes up through rain-filled hollows, and a coin dropped into a bubbling puddle blackens within minutes. The lake also stirs, and hands back what it swallows: old tree trunks have risen out of the tar, stood proud a while and sunk again, and Amerindian tools and a human skull have come back up preserved. Lake Asphalt, the state company holding the lease since 1978, still cuts about 180 tonnes a day, and fresh pitch closes the wagon scars by morning. The lake itself is not so durable: it has been shrinking since the 1890s, and the village on top is sinking with it, roads buckling as the tar creeps beneath them.