National Geographic : 1894 May 23
The Peneplainin Virginia. is not so well marked as about Asheville. Considerable study has been given to the region just north of this province by Davis, who suggests in the paper above cited* the probability of the extension of the Cretaceous peneplain over the entire southern Appalachians. Though he makes no definite statements as to its elevation and attitude, yet he concludes that the summits of the Blue ridge, south of the Pennsylvania line, probably repre sent this baselevel. The present writers have searched quite carefully for definite evidence as to the existence of the pene plain in this region and so far have been unable to find any thing entirely satisfactory. That the region in question was baseleveled is conceded by all who are familiar with its topog raphy, but the present elevation and attitude of the peneplain are less certain. Southeast of the Blue ridge there are a few outliers or isolated knobs standing above the Tertiary plain, and these show a uniform altitude of about 1,000 feet. It seems scarcely possible that these outliers should have been reduced to so nearly a common level unless that level were the baselevel of erosion. Immediately north of the Blue ridge, the Massannutten mountain shows traces of baseleveling at alti tudes varying from 2,400 to 2,500 feet, and the valley ridges to the northward probably show traces at still greater altitudes. The Blue ridge varies greatly in altitude: its crest rises toward the south from 1,200 feet at Harpers Ferry to 4,000 feet at the Peakes of Otter, in central Virginia, and toward the north to 2,300 feet on the Maryland-Pennsylvania line. If there were a corresponding gradient in the peneplain it would necessitate a deformation along a cross-axis, of which there is no trace further westward; also the crest line of the Blue ridge between the points mentioned is extremely irregular and bears no resemblance to the remnant of a baseleveled plain. The varying elevations of the plain, determined on either side of the Blue ridge, agree with certain features of the ridge itself and make it decidedly probable that the peneplain here is highly tilted eastward; the strike of the plain-i. e., the direction of the contours representing the restored surface-crosses the ridge at a low angle instead of being parallel with it. The result of these complex conditions is that no two remnants of the old plain are found along the trend of the ridge at the same altitude, and consequently they are extremely difficult to recognize. Assuming this attitude of the peneplain * Bull. Geol. Soc. Am., vol. ii, 1891, p. 562.
1894 Jun 22
1894 Apr 25