Science Common Sense

641 - What is petroleum, and how is it formed?

Petroleum is a thick, gooey liquid that is found deep under the Earth's surface. It's also known as oil.

Petroleum is formed from the remains of tiny plants and animals that lived millions of years ago. Here's how:

1. These plants and animals died and sank to the ocean floor.
2. Over time, layers of sand and mud covered them, pressuring them and keeping out oxygen.
3. The heat from the Earth and the pressure transformed them into a liquid, which is now petroleum.
4. As more layers were added on top, the liquid got trapped and formed pools under the ground.

It takes millions of years to form petroleum. That's why it's called a fossil fuel, because it comes from ancient fossils.