a tectonically relatively stable and level area of the ocean floor. The term was introduced by the Australian geologist R. Fairbridge in 1955 in connection with the beginning of the study of the geology of the oceans. With the discovery in the 1960’s and 1970’s of the worldwide system of mid-ocean ridges, which are tectonically active (mobile) belts of the ocean floor, it became obvious that thalassocratons cannot include these ridges. Therefore, some researchers gave other names, such as “ocean plates” or “thalassoplains,” to the relatively stable sectors of ocean bottom outside the boundaries of the mid-ocean ridges. In the framework of the new global tectonics, or plate tectonics, thalassocratons are parts of the plates of the lithosphere.