=Dissected peneplains.= When a rise of the land brings one cycle to an end and begins another, the characteristic land forms of each cycle are found together and the topography of the region is composite until the second cycle is so far advanced that the land forms of the first cycle are entirely destroyed. The contrast between the land surfaces of the later and the earlier cycles is most striking when the earlier had advanced to age and the later is still in youth. Thus many peneplains which have been elevated and dissected have been recognized by the remnants of their ancient erosion surfaces, and the length of time which has elapsed since their uplift has been measured by the stage to which the new cycle has advanced. [Illustration: Fig. 65. Describe the valley of stream _a_. Is it young or old? How does the valley of _b_ differ from that of _a_? Compare as to form and age the inner valley of _b_ with the outer valley and with the valley of _a_. Account for the inner valley. Why does it not extend to the upper portion of the course of _b_? Will it ever do so? Draw longitudinal profile of _b_, showing the different gradient of upper and lower portions of its course not here seen. As the inner valley of tributary _c_ extends headward it may invade the valley of _a_ before the inner valley of _a_ has worked upstream to the area seen in the diagram. With what results?] =The Piedmont Belt.= As an example of an ancient peneplain uplifted and dissected we may cite the Piedmont Belt, a broad upland lying between the Appalachian Mountains and the Atlantic coastal plain. The surface of the Piedmont is gently rolling. The divides, which are often smooth areas of considerable width, rise to a common plane, and from them one sees in every direction an even sky line except where in places some lone hill or ridge may lift itself above the general level (Fig. 62). The surface is an ancient one, for the mantle of residual waste lies deep upon it, soils are reddened by long oxidation, and the rocks are rotted to a depth of scores of feet. At present, however, the waste mantle is not forming so rapidly as it is being removed. The streams of the upland are actively engaged in its destruction. They flow swiftly in narrow, rock-walled valleys over rocky beds. This contrast between the young streams and the aged surface which they are now so vigorously dissecting can only be explained by the theory that the region once stood lower than at present and has recently been upraised. If now we imagine the valleys refilled with the waste which the streams have swept away, and the upland lowered, we restore the Piedmont region to the condition in which it stood before its uplift and dissection,--a gently rolling plain, surmounted here and there by isolated hills and ridges. [Illustration: Fig. 66. Dissected Peneplain of Southern New England]