Where do fossil fuels come from?

You may be surprised to know that oil and natural gas are produced from dead animals that lived millions of years ago, 570 million years ago to be exact. Back then, in what scientists call the Paleozoic Era, New Mexico wasn’t anything like it is today. It was under the ocean!

But even the ocean wasn’t like it is today. There were no sharks, dolphins, seahorses or any kind of animal we know in this ocean, millions of tiny creatures called plankton were food for larger animals such as trilobites, crinoids and brachiopods…

Trilobites are hard-shelled, segmented  creatures that lived over 300 million  years ago.  They went extinct before  dinosaurs even existed.  When  scientists were learning about different  eras in time, they discovered that  trilobites were one of the key creatures  of the Paleozoic Era.

Trilobite Fossil

Trilobites are hard-shelled, segmented creatures that lived over 300 million years ago. They went extinct before dinosaurs even existed. When scientists were learning about different eras in time, they discovered that trilobites were one of the key creatures of the Paleozoic Era.

 

Crinoid Fossil

Crinoids are known as sea lilies because they live on a stem and have a body that looks like a flower. They kind of look like starfish, except for the stem. Crinoids were abundant in the shallow tropical seas during the Paleozoic Era, but they are very uncommon today.

 

 

 

 

 

Brachiopod Fossil

Brachiopods are marine animals that look like clams because they have two shells, but they are really quite different. They usually make their homes in very cold water, either deep in the ocean or towards the North and South Poles. Because of where they live, most people never see brachiopods.

You may be asking, what do these animals have to do with oil and gas? The answer is that they ARE oil and gas. Check it out…

As these and other animals died, their skeletons would be buried under mud and sand, which protected them from harsh conditions in the ocean. Once the bones of the animal hardened, the surrounding material would form around it, preserving the shape forever. This is called a fossil.

320 million years passed and by then the ocean floor was covered with fossils and dead plankton. This was during the Mesozoic Era, when dinosaurs roamed the earth. The water level dramatically dropped because of evaporation, so the fossils were no longer under water, but they were still protected by mud and sand. New material started to pile up on the fossils, pushing them deeper into the earth and causing huge amounts of heat and pressure.

After 250 million years of heat and pressure, the fossils began to change from their organic state into hydrocarbons, which are substances containing both hydrogen and carbon. The hydrocarbons are protected by sedimentary rock. The rock can effectively protect the hydrocarbons because it is inorganic and contains no carbon.

The hydrocarbons have now been subjected to temperatures ranging from 150 to 300 degrees Fahrenheit for millions of years. All the pressure and heat creates a chemical change in the hydrocarbons, which creates oil and natural gas.

Now you can see how fossils formed long ago make fuel today. That’s why we call them fossil fuels!

For more information check out our glossary of terms.