National Geographic : 1894 May 23
76 Hayes and Campbell-Appalachian Geomorphology. as a working hypothesis, traces of a baselevel can be found in places that otherwise afford no evidence of its existence; a terrace cut here and a wind-gap there serve to locate the plain so that it can be restored and contoured with consider able confidence. The restored surface corresponds with the summits of the ridges at Harpers Ferry, where proximity to the Potomac insured complete reduction to baselevel and afforded opportunity for subsequent erosion to almost completely dissect the plain. On either side, away from the river, the crests become more irregular, and evidently stand above the peneplain, while the present wind-gaps show traces of baseleveling, and probably correspond in altitude very nearly with the plain. On the east ern side of the Blue ridge throughout North Carolina there is but little data available for reconstructing the Cretaceous pene plain. The present writers are personally unacquainted with the region and a large part of it has never been mapped with contours. At only one point has the phenomenon of baselevel ing been recognized. Kerr has described certain topographic features observed in the vicinity of Morganton, North Carolina,* and likened them to the Asheville baselevel. His theory as to their glacial origin cannot.be accepted, but from his description it may be inferred that the valley of the Catawba river has been baseleveled to about the same extent as the French Broad at Asheville, and that the plain has been nearly as well preserved. Its altitude here is 1,400 feet, so that it must have a very rapid ascent toward the west in order to reach an altitude of 2,400 or 2,500 feet at Asheville, which is only fifty miles distant. This sharp ascent of the Cretaceous peneplain on the eastern slope of the Blue ridge dies out rapidly southward, partly through the flattening out of the fold in that direction and partly through the influence of a cross-axis of depression in the vicinity of Atlanta. Southern marginal Type.-In the region southwest from Atlanta as far as the Coosa river the present attitude of the peneplain differs from that in any other portion of the province. In this region the baseleveled plain has suffered but little uplift from the position in which it was formed, and this slight elevation has taken place in very recent geologic time. Hence the pene plain is well preserved and many of the present streams, as the * Origin of new Points in the Topography of North Carolina, by W. C, Kerr: Am. Jour. Sci., 3d series, vol. xxi, 1881, pp. 216-219.
1894 Jun 22
1894 Apr 25