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.
Apr 21, 2011 3 Comments by Richard Douthwaite. The development of techniques which allow the extraction of gas from some carboniferous rocks known as shale has completely transformed the worldâs natural gas market.