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.
Definition of 'Natural Gas'. Definition: Natural gas is a mixture of gases which are rich in hydrocarbons. All these gases (methane, nitrogen, carbon dioxide etc) are naturally found in atmosphere. Natural gas reserves are deep inside the earth near other solid & liquid hydrocarbons beds like coal and crude oil.