In general, irregular periods are very common during the perimenopause. The most common early menstrual irregularity noticed in the perimenopause is a shortening of cycle length.
Abiogenic petroleum origin. Abiogenic petroleum origin is a term used to describe a number of different hypotheses which propose that petroleum and natural gas are formed by inorganic means rather than by the decomposition of organisms.
Natural gas is a type of fossil fuel (formed from the remains of dead plants and animals) that largely consists of methane, but also contains other components such as ethane, butane, propane, carbon dioxide or hydrogen.