National Geographic : 1890 May
National Geographic Magazine. tie slope of the newly revealed Cretaceous cover. It was at that time a compound, composite river :* compound because it drained areas of different ages; composite, because these areas were of different structures. Existing examples of compound, composite rivers are seen in the Catawba, the Yadkin-Pedee, the Cape Fear and the Neuse rivers of North Carolina, which all rise on the inland crystalline area, and traverse the coastal quaternary plain before reaching the sea. But unlike these, there must have been, when the old submerged land rose with the Cretaceous cover on its back, numerous small streams whose drainage area lay entirely within the Cretaceous plain. These were simple streams, flowing over a structure of one kind and one age. Their modern homo logues are seen in the Maurice, the Great and Little Egg Harbor and the Wading rivers of southern New Jersey, and I suppose also in various relatively short streams of North Carolina, such as the Lumber, Great Cohera and Moccassin. It cannot be supposed that the original Pequannock-Passaic possessed the large southern branch, which I shall call the upper Passaic, by which Great Swamp is now drained ;f for had this been the case, the divides between the branches of the upper Passaic and the heads of the small streams that now still cross both of the trap ridges, must have long ago been driven to a stable position on the crest line of the inner ridge. The upper Passaic member of the Pequannock-Passaic system must be re garded as a branch of subsequent development, guided by some of the softer Triassic beds when they were reached beneath the Cretaceous cover, and very successful in capturing and diverting other transverse streams that were smaller than its master. For some distance on either side from the Pequannock-Passaic gap in the trap ridges at Patterson, the existing streams are perfectly adjusted to the Triassic structure ; that is, the ridges are persis tent divides, and the lateral subsequent branches of the master flow along the strike of the softer shales and sandstones, except where lately thrown off their courses by glacial drift barriers. This I interpret as meaning that the Pequannock-Passaic master *See terminology suggested by the author. Nat. Geogr. Mag., i, 1889, 218. t It should be recognized that the present round-about drainage of the Great Swamp is a post-glacial feature, determined by the morainic bar rier that crosses the basin from Summit (S) to Morristown (M) : the pre glacial drainage of the southern part of the inner crescent was un doubtedly of a simpler and more direct pattern.