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 etha â¦ ne, butane, propane, carbon dioxide or hydrogen.  Natural gas is mainly methane, CH4.