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.
The term geological processes describes the natural forces that shape the physical makeup of a planet. Plate tectonics, erosion, chemical weathering and sedimentation are all examples of forces that significantly affect the Earthâs surface and account for its major features.