Fossil fuels consist of decomposed plant and animal matter.
After millions of years, layer upon layer of earth forming the various fossil fuels compressed the prehistoric remains of animals, such as dinosaurs. Due to the extensive amount of time it takes for these fossil fuels to form, they are known as non-renewable resources. Because these resources are non-renewable and are so widely used, our fossil fuel energy resources are quickly becoming depleted. Fossil fuels also provide us with many other problems such as pollution, high costs, and health risks. For these reasons, alternative sources of energy must be found.