upheaval (upheval)

The act of upheaving, or the state of being upheaved; a heaving or lifting up; specifically, in geol., a disturbance of a part of the earth's crust, having as one of its results that certain areas occupy a higher position with reference to adjacent areas than they did before the disturbance took place. Upheaval is a part of the proce by which mountain chains have been formed; it is the opposite of subsidence. The subsidence of one region may cause the apparent upheaval of another adjacent to it. - Doctrine of violent upheavals. Same as theory of cataclysms (which see, under cataclysm ).