How is oil formed? The generally accepted theory is that today’s oil reserves come from organic materials that existed millions of years before dinosaurs roamed the earth. About 300 million years ago, these dead organic materials such as zooplankton and algae built up on the bottom of lakes and oceans in conditions where they couldn’t decompose. The organic matter then changed into kerogen, which eventually turned into oil through heat and pressure.
This infographic details how oil is formed, while also covering some of oil’s uses and history.