. Annals of the New York Academy of Sciences. Science. 8 ANNALS NEW YORK ACADEMY OF SCIENCES mature valleys have been opened out below the general upland by such streams as the Saco Eiver and the Merrimac and its tributaries. When consideration is given to the final stage of a stream's history, that of old age, after erosion has reduced the entire drainage basin to an almost flat surface, the instructor is able to place before his class an unparalleled example in the New England peneplane (Fig. 4). The even crest of the Palisades truncating the westward dipping formations, and impressive for t
. Annals of the New York Academy of Sciences. Science. 8 ANNALS NEW YORK ACADEMY OF SCIENCES mature valleys have been opened out below the general upland by such streams as the Saco Eiver and the Merrimac and its tributaries. When consideration is given to the final stage of a stream's history, that of old age, after erosion has reduced the entire drainage basin to an almost flat surface, the instructor is able to place before his class an unparalleled example in the New England peneplane (Fig. 4). The even crest of the Palisades truncating the westward dipping formations, and impressive for this reason, serves as an illustrative example close at home. Throughout New England, the Hudson Highlands, Schooley Mountain, the rest of the Highlands of New Jersey, and Kittatinny Mountain, the even crest lines of the folded ridges of Pennsylvania, and the Blue Eidge of Virginia this same peneplane finds expression and is known variously as the New England, the Schooley, the Kittatinny, and the Cretaceous peneplane. It is true that this peneplane no longer stands Mt. Haystack^ The New England Upland in western Massachusetts field sketch. Fig. 4.—Sketch of Netv England peneplane having an elevation of 1^00 feet in western Massachusetts As seen looking west from Mt. Massaemet, near Shelburne Falls. Two or three monadnocks rise above the peneplane, and the Deerfield River has incised itself several hundred feet below that level. at the level to which it had been reduced. The fact that it has been elevated only makes it the more valuable as an object for study. It pro- vides an example when rejuvenation and the matter of several cycles are discussed. The gorge of the Deerfield Eiver (Fig. 4) and many other New England streams cut below the upland level serve to illustrate the essential features of a topography first reduced to old age and then dis- sected as a result of later uplift, but even still finer examples are to be had in the case of the Monongahela Eiver in
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1877
