There are lots of places, all around the world, where oil and natural gas seep up out of the ground on their own, with no help from human beings. In fact, these places are probably how our ancestors first came to use fossil fuels.
But some seeps are more impressive than others. There are only a few places in the world where seeps become large enough to be called lakes. Rancho La Brea in California is probably the most famous. You'll remember it as the place with all the fossils. Mammoths, dire wolves, and saber-toothed cats all wandered into the tar pit, became stuck, and died—leaving pitch-stained bones for researchers to find thousands of years later.
And that well-known story is part of what makes Pitch Lake on the island of Trinidad so confounding. In the photo above, you'll notice people walking across the semi-solid surface of the asphalt lake.* This is not an anomaly. There's videos of tourists doing the same thing all over the Internet, and locals talk about kids playing soccer and cricket on the lake like it's an asphalt playground.
I want to do some more research into this, but it seems as though the consistency of Pitch Lake is, at least for part of the year, fundamentally different from the consistency of the Rancho La Brea Tar Pits. Instead of becoming stuck, people and animals can move across a semi-solid surface. Stand in one place for too long, and you'll start to slowly sink down. But even then you can step back out relatively easily, and as long as you keep moving there's no problem. Apparently, the only time Pitch Lake is dangerous is on very hot days.
Another fascinating thing that distinguishes Pitch Lake from its more famous cousin: Pitch Lake is actively being mined. Asphalt from the lake has been commercially extracted and shipped worldwide for 100 years. It's used to waterproof pipes and pave roads. In 2008, an Australian Broadcasting Corporation show reported that this mining is slowly lowering the level of Pitch Lake. At current extraction rates, it'll be gone in 400 years.
*If I'm understanding correctly, the water you see in the middle of the photo isn't a patch of open water, but a shallow rain pool that's formed on the surface of the asphalt. These pools are home to some of the hardiest microbes on Earth.
Image: IMG_3110, a Creative Commons Attribution (2.0) image from xenocrates's photostream.
