The material found in the Earth that is the main source of methane is organic matter. Organic matter is composed of the remains of plants and animals, and it is found in soil, sediment, and water. When organic matter is decomposed by bacteria, it produces methane gas. This process is called methanogenesis.

Methanogenesis is a natural process that occurs in many environments, including wetlands, landfills, and the digestive systems of animals. However, human activities can also increase the production of methane gas. For example, the burning of fossil fuels releases carbon dioxide into the atmosphere, which can then be converted into methane by bacteria. Additionally, the clearing of forests and the draining of wetlands can also release methane gas into the atmosphere.

Methane is a potent greenhouse gas, and it is a major contributor to climate change. Therefore, it is important to understand the sources of methane gas and to take steps to reduce its emissions.