Natural gas deposits are often found near oil deposits. Deposits of natural gas close to the Earth’s surface are usually dwarfed by nearby oil deposits. Deeper deposits—formed at higher temperatures and under more pressure—have more natural gas than oil. The deepest deposits can be made up of pure natural gas. “Normal”, or, in the oil business langage, “conventional” oil, designates a liquid mainly composed of molecules of hydrocarbons, that is made only of carbon and hydrogen, with anything between a couple and a couple hundred atoms of carbon per molecule. This “normal” oil also contains, Oil and natural gas, also called fossil fuels, are formed by anaerobic decomposition of dead and buried organisms. Anaerobic decomposition is the decomposition of something while lacking oxygen, which is caused by it being buried in mud and sediment, which over time (millions of years) will cause favorable conditions for fossil fuels to form.