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.
What do petroleum an natural gas form from? Petroleum is a dark, stick and viscous liquid. It is formed by the deposition of the remains of algae and animals on the seabed.