Crustal deformations of gradual type

Crustal deformations of gradual type may be observed in very different ways: horizontal shifting of large areas may be found by astronomical observation (change in latitude), or by comparing radio time signals from far distant points with the astronomically controlled time of the place under consideration (change in longitude); movements of block , one relative to the other, may be discovered by geological investigations.; clear indications of vertical movements are often shown by changes in shore-lines (direct observations) or by continuous records of tide gauges; finally, relatively accurate data are provided in all cases by geodetic measurement, either triangulation, or precise levelling.