How is Crude Oil Formed?

Prehistoric dead, organic material (ancient animals, plants) accumulated on the bottom of oceans, riverbeds, swamps, etc., mixing with mud and sand. Over time, sediment piles on top resulting in heat and pressure transforming the organic layers into dark and waxy substance known as kerogen. Left alone, kerogen molecules crack, breaking up into shorter and lighter molecules composed of carbon and hydrogen atoms. Depending on how liquid or gaseous this mixture is, it will turn into either petroleum or natural gas. Most scientists theorize this process is probably hundreds of thousands of years. You can find more information here: