FIG. 271.—Ragged coast line of Alaska, the effect of subsidence.] =A ragged coast line the mark of subsidence.=—When in place of uplift a subsidence occurs upon the coast, the intricately etched surface, resulting from erosion beneath the sky, comes to be invaded by the sea along each trench and furrow, so that a most ragged outline is the result (Fig. 271). Such a coast has many harbors, while the uplifted coast is as remarkable for its lack of them. =Slow uplift of the coast—the coastal plain and cuesta.=—A gradual uplift of the coast is made apparent in a progressive retirement of the sea across a portion of its floor, thus exposing this even surface of recent sediments. The former shore land will be easily recognized by it’s etched surface, which will now come into sharp contrast with the new plain. It is therefore referred to as the _oldland_ and the newly exposed _coastal plain_ as the _newland_ (Fig. 272). [Illustration: FIG. 272.—Portion of Atlantic coastal plain and neighboring oldland of the Appalachian Mountains.] But the near-shore deposits upon the sea floor had an initial dip or slope to seaward, and this inclination has been increased in the process of uplift. The streams from the oldland have trenched their way across these deposits while the shore was rising. But the process being a slow one, deposits have formed upon the seaward side of the plain after the landward portion was above tide, and the coastal plain may come to have a “belted” or zoned character. The streams tributary to those larger ones which have trenched the plain may encounter in turn harder and softer layers of the plain deposits, and at each hard layer will be deflected along its margin so as to enter the main streams more nearly at right angles. They will also, as time goes on, migrate laterally seaward through undermining of the harder layers, and thus will be shaped alternating belts of lowland separated by escarpments in the harder rock from the residual higher slopes. Belts of upland of this character upon a coastal plain are called _cuestas_ (Fig. 273). [Illustration: FIG. 273.—Ideal form of cuestas and intermediate lowlands carved from a coastal plain (after Davis).] =The sudden uplifts of the coasts.=—Elevations of the coast which yield the coastal plain must be accounted among the slower earth movements that result in changes of level. Such movements, instead of being accompanied by disastrous earthquakes, were probably marked by frequent slight shocks only, by subterranean rumblings, or, it may be, the land rose gradually without manifestations of a sensible character.