High Quality Content by WIKIPEDIA articles! Hydrothermal circulation in its most general sense is the circulation of hot water; `hydros` in the Greek meaning water and `thermos` meaning heat. Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth`s crust. This generally occurs near volcanic activity, but can occur in the deep crust related to the intrusion of granite, or as the result of orogeny or metamorphism.