=The maturely dissected upland.=—Continued ramifications by the rivers eventually divide the entire upland area into separated parts, and the rounding of the shoulders of valleys proceeds simultaneously until of the original upland no easily recognizable compartments are to be found. Where before were flat hilltops are now ridges or watersheds, the well-known _divides_. The upland is now said to be completely dissected or to have arrived at _maturity_. The streams are still vigorous, for they make the full descent from the upland level to base level, and yet a critical turning point of their history has been reached, and from now on they are to show a steady falling off in efficiency as sculpturing agents. [Illustration: FIG. 177.—View of a maturely dissected upland from one of its hilltops, Klamath Mountains, California (after a photograph by Fairbanks).] Viewed from one of the hilltops, the landscape of this stage bears a marked resemblance to a sea in which the numberless divides are the crests of billows, and these, as distance reduces their importance in the landscape, fade away into the even line of the horizon (Fig. 177). =The Hogarthian line of beauty.=—Since the youthful stage of the upland, when the lines of its landscape were straight, its character rugged, and its rivers wild and turbulent, there has been effected a complete transformation. The only straight line to be seen is the distant horizon, for the landscape is now molded in softened outlines, among which there is a repeated recurrence of the line of beauty made famous by Hogarth in his “Analysis of Beauty.” As well known to all art students, this is a sinuous line of reversed or double curvature—a curve which passes insensibly at a point of inflection from convex to concave (Fig. 178). The curve of beauty is now found in every section of the hills, and it imparts to the landscape a gracefulness and a measure of restfulness as well, which are not to be found in the landscapes of earlier stages in the erosion cycle. In the bottoms of the valleys also the initial windings of the rivers within their narrow flood plains add silver beauty lines which stand out prominently from the more somber background of the hills. [Illustration: FIG. 178.—Hogarth’s line of beauty.] Considered from the commercial viewpoint, the mature upland is one of the least adaptable as a habitation for highly civilized man. Direct lines of communication run up hill and down dale in monotonous alternation, and almost the only way of carrying a railroad through the region, without an expenditure for trestles which would be prohibitive, is to follow the tortuous crest of a main divide or the equally winding bed of one of the larger valleys. [Illustration: FIG. 179.—View of the old land of New England, with Mount Monadnock rising in the distance.]