Question

How is oil made in our earth?

Answer 1

Large amounts of organic matter are buried and trapped between layers of rock. The organic matter decomposes without the presence of oxygen and turns to oil.

Explanation:

During the Mesozoic Era the earth was much warmer overall. There was a high level of `CO_2` in the atmosphere. The combination of warmth and carbon dioxide caused the production of large amounts of organic matter.

Due to large geological shift in the earth this organic matter was buried under layers of sediment that turned into hard rock. The organic matter decomposed turning into the hydrocarbons that are called oil and natural gas.