If the structure of that part of North America between the deep gulfs of Mexico and those which compose Iludson's hay and Davis' straits was care fully and scientifically examined, it would be very probably found, that the Appalachian system of mountains is not confined to the United States, nor limited to the extent usually assigned to it on even our best maps. But, as correctly known, this system appears to rise in lateral chains, and to form the base of an immense continental protuberance, elon gated from southwest to northeast, and maintain ing a course in general accordance with that of the adjacent Atlantic coast. On the southwest, towards the gulf of Mexico, the Appalachian chains rise imperceptibly from the general level of the coun try; but it is a common and great error to suppose these mountains to be confounded with the hills. Though at the extremes, and particularly at that of the southwest, the Appalachian chains sink gradu ally; these chains arc every where, if at all visible, utterly distinct from those remains of abrasion by water, called hills. If we suppose the whole Appa lachian region to have once formed a gradual and regular protuberance, without any valley or hill, and then suppose this parabolic surface exposed to the action of water, hills and valleys must be the necessary production; but this, nor any ordinary known operation of nature, by the agency of water, will tend to form a mountain. The action of water may, and no doubt does, by wearing away and dis placing the soil, expose mountain masses. This latter operation is yet in progress, as may he seen by a cursory survey; but the effect is very different from what would be requisite to form a mountain.
A long and careful examination of the rivers en tirely round the Appalachian region, first suggested to the writer a suspicion that the mountains which compose the nucleus of this system were deeply laid in the earth, and that what is in common language called " the mountains," were only prominent ridges emerging from the surface. The Chippewayan re gion I have never had means to examine, but from analogy am inclined to the induction, that there also, if examined, the laws of structure would be found similar to those which regulated the Appa lachian system. With these preliminary remarks, we proceed to a general physical view.
It has already been remarked, that the United States comprised four vast inclined planes. Per haps the natural structure would be more easily and more correctly comprehended by regarding this great physical region as comprising the two distinct mountain systems; the Appalachian on the east, and Chippewayan on the west, and then view the adjacent and dependent slopes or inclined planes as only parts of the mountain systems.
The Appalachian system, as defined on the gene ral maps of the United States, is divided into two great sections by the tide vale of Hudson's river. This very remarkable natural water separation has induced many to consider the two mountain regions on each side, as distinct systems, but we shall soon sec adequate element to demonstrate the connexion, although. the Atlantic tides are rolled through the
gaps which intervene. The Hudson forms, how ever, a demarcation altogether sufficient to warrant its adoption in classifying the natural features of the United States, and to justify separating, in our description, the Appalachian system into two sec tions, that of the southwest, and that of northeast.
The southwestern section rises very prominent from the Hudson valley, at two distant points. At the distance of very nearly one degree of latitude north from the outlet of the Hudson into the At lantic ocean, and between N. Lat. 41° 20', and 41' 30' the tides are borne into the interior of the con tinent between enormous walls of native rock, rising to from 1200 to 1500 feet above the high water level. To the primitive mariners who dis cerned the Hudson, this passage, now appropriate ly called the Highlands, must have appeared on a distant view, as an impassable barrier, in place of an opening to the concealed regions beyond. But clearing this narrow, and deep vale, the distant ridges of mountains seem to lie scattered on the far distance, until advancing about one degree of latitude farther north, the masses again rise to be tween 3000 and 3500 feet. This very striking group now called the Catskill, or Catsberg chain, discharging the Delaware river to the southwest and the Schoharie river to the north, seem, when first viewed ascending the Hudson, as if the chains at their bases rose from the stream, though at the nearest ten miles distant. The oceanic level of the Hudson gives full elevation of view and raises the peaks of the Catsbergs to no imposing height. Amongst the objects brought before the voyager for the first time up the Hudson the mountains ar rest far most attention. Those parts of the north east section of the Appalachian system are seen distinctly, but on the edge of the horizon, whilst the Highlands and Catshergs protrude their masses into the very presence of the observer.
If we assume the extreme of the southern side of the Highlands, and the northern of the Cats bergs, as the breadth, the Appalachian system con tiguous to the channel of the Hudson is something about 90 miles wide. A line, however, parallel to the Hudson, cuts the system rather obliquely. but even when traversed at right angles from High lands, the system is upwards of 80 nudes wide.
From the Hudson valley the chains, in no place clearly defined, range nearly southwestward into the basin of the Delaware, hut with diminished height. Before we advance farther with the gene ral description, we may pause to remove, by stating a few facts, a very general error as respects the connexion of the rivers with the mountains of the United States.