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 does petroleum and natural gas form? natural gas- a mixture of gaseous hydrocarbons located under the surface of the earth, often near petroleum deposits; used as a fuel. petroleum- liquid mixture of complex hy â¦ drocarbon compounds; used wisely as a fuel source.