CHAPTER IX.
THE MOVEMENTS AND DEFORMATIONS OF THE EARTH’S BODY (DIASTROPHISM).
The body of the earth is subject to an infinite variety of movements, ranging from the almost inconceivably rapid to the almost imperceptibly slow, and from the almost immeasurably minute to the enormously massive; but, for practical treatment, they fall mainly into two couplets: (1) the minute and rapid, and (2) the slow and massive. Sudden movements of local masses, giving rise to intense vibrations, are put in the first class. There are innumerable minute and slow movements, but unless they rise to appreciable magnitude by long continuance, they are neglected.