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.
In the geological carbon cycle, carbon moves between rocks and minerals, the Earth's oceans, and the atmosphere. Carbon dioxide in the atmosphere reacts with different minerals to form the mineral calcium carbonate (limestone) through a process called weathering.