1902 Encyclopedia > United States > The Appalachian System

United States
(Part 15)


Part 15. The Appalachian System

The Appalachian ranges all belong to an ancient system of uplift or disturbance, and have not been invaded by volcanic materials of recent date, presenting in both these respects a most marked contrast to the Cordilleran system. There are volcanic rocks along portions of the eastern slope of the Appalachians; but these eruptive dikes and overflows are not of Tertiary and post-Tertiary but of Mesozoic age.

The name Appalachian is used as designating the entire complex of ranges, valleys, and tablelands in and upon which is situated the watershed from which on the north and east the streams descend to the Atlantic, either directly or through the Great Lakes, and on the west and south-west to the Gulf of Mexico, either as tributaries to the Mississippi or flowing directly to the Gulf., As thus defined, the Appalachian region, system, or complex of ranges extends from the promontory of Gaspe, in a mean direction of north-east and south-west, to Alabama, a distance of about 1300 miles, where it disappears under the much more recent geological formations which form a broad belt along the Gulf of Mexico and extend far up the Mississippi valley.

While the Appalachian system, as a whole, is so nearly continuous, as a feature of the topography of the country, that it seems necessary to include it all under one general designation, yet different portions are extremely unlike each other in some of those features which are generally looked upon as essential to the unity of a mountain system.

One very marked and important break at least in the system is that occupied by the Hudson river, and extending up the Mohwak valley to the west, to a connection with the Great Lakes, and up the Champlain valley to the north, to a connection with the St Lawrence river direct. A rise of 152 feet in the sea-level would isolate from the rest of the continent all of New England and that part of Canada lying to the south-east of the St Lawrence, as far as the extremity of Gaspe. A further rise of 278 feet would open a waterway from the Atlantic to be Great Lakes, and leave the mass of the Adirondacks as an island lying adjacent to New England on the east and the Applachian land-mass on the south. We seek in vain for any other break in the Appalachian system as complete as this, and, when we compare the portions of the system lying on each side of this line of division, we recognize the fact that there are essential points in which they differ from each other, and that these differences are greater than any presented by the various portions of the system in its extension to the south-west of the Hudson river break. This north-eastern division of the Appalachians may therefore properly first have its more important topographical and geological features indicated.

Beginning with the division west of Lake Champlain and north of the Mohawk valley – the Adirondack region or mountains – we find, on examination, that this region is not only to a certain extent isolated topographically from the rest of the Applachian ranges, but that it belongs to a geological older system. The rock are all eruptive in the central portion of the mass, and chiefly gabbro and granitic or gneissoid in character. On the exterior, especially on the eastern edge, are deposits of limestone, which are generally believed by geologists to be sedimentary beds, highly metamorphosed, but which, in the opinion of the present writer, are more probably of the nature of chemical precipitates.

The drainage of this region is radial from a central point, but the slope on the east is shorter than on any of the other sides. From Tahawas or Mount Marcy (5344 feet0 the drainage is to the north-east by the Au Sable to Lake Champlain, by the Raquette to the St Lawrence, and by the branches forming the head waters of the Hudson to the south. The dominating line of elevations runs nearly east and west, with high spurs and narrow ridges on the north, of which Whiteface Mountain (4871 feet) is one of the most conspicuous. The region is one of numerous lakes and lake-like expansions of the rivers, so that, with short portages, a large part of it can be visited by boat or canoe. The lake region proper of the Adirondacks lies at an elevation of from 1500 to 2000 feet: - Lake Silver, 1983 feet; Placid, 1950; Saranac (Upper), 1606, (Lower), 1557; Smith’s, 1738; Tupper’s, 1504; Long, 1584; Raquette, 1765; Sandford, 1685; Cranberry, 1570. There are indicating of the Appalachian trend in the north-east south-west, direction of several of the larger lakes; but many others trend nearly north and south. The number of the lakes is the result of the impermeability of the rock, the general uniformity in height of the region, and the broken character of the surface, which is very irregularly covered by large masses of rolled detritus. The work of water is everywhere distinctly visible, and that of ice hardly perceptible.

The mountainous region east of the Hudson in New England is the portion of the system most irregular in topographical features. Two groups of elevations, however, are quite well marked, and have distinctive names-the Green and the White Mountains. These are separated by the Connecticut river, which has a nearly north and south course parallel to the range of the Green Mountains. Nowhere in this latter range is there a continuous uplift forming a long ridge or crest, but there is a gentle swell of the surface on which here and there rise elongated groups of considerably higher summits. In the extreme southwestern corner of Massachusetts rises Bald Peak (2624 feet), and in the north-western corner Graylock or Saddle Mountain (2505 feet). Still farther north, in Vermont, are the culminating points of the Green Mountain range: - Equinox, 3872 feet; Pico, 3935; Camel’s Hump, 4077; Killington, 4221; and Mansfield, 4389 feet. Ascutney, a quite isolated point, near the Connecticut river, has an altitude of 3163 feet.

The Connecticut river makes a very complete separation, in all but the extreme northern portion of its course, between the Green Mountain system and the highlands to the east, which have no collective name, but are in a measure the continuation of the White Mountain range. In Massachusetts this swell of land – for more it can hardly be called – has an elevation of about 1000 feet, the valleys being rarely sunk more than 200 or 300 feet below the general level of the gently undulating higher lands. Occasionally there is a higher point, like Wachusett (2018 feet) or Monadnock (3169 feet). From Monadnock the region east of the Connecticut broadens very much, the coast-line trending rapidly eastward. The country becomes more and more mountainous, but still without continuous ranges. The mountains are grouped around various central points, of which the most important are Moosilauke or Moosehillock (4790 feet), Lafayette (5290), and Washington (6290 feet). The last-named is the highest point in the Applachian system north of North Carolina, and rises nearly 500 feet above all the adjacent summits.

Farther east, in Maine, and in the neighboring portions of Canada, the topography has been little worked out in detail. So far as known, in Maine the irregularity of the range is still greater than it is farther to the south-west. There is in this part of New England no coast-region, but a gradual rise from the seashore towards the interior for about 140 miles, to the divide between the waters running into the Atlantic directly and those tributary to the St Lawrence of forming the head of the St John. This divide, which has a general direction of pretty nearly east ad west, is at an altitude of about 1800 feet at the western edge of Maine, and declines to about 600 feet on its eastern boundary. The southern slope is a very gradual one to the sea, and though broken and rocky is not diversified by any marked ridges or long elevation. The high points rise sometimes nearly isolated, and sometimes in clusters, having little of the ridge character. Ktaadn (Katahdin) is the dominating peak (5215 feet), and it rises in such isolation as to look in the distance like a volcanic cone. That part of Maine lying south of the watershed is drained by streams running nearly southward. Like the Adirondack Wilderness, it is a district of numerous lakes, as might be expected, since it has no rapid descent in any direction, is underlain by impermeable rocks, and has a considerable rainfall.

The general uniformity of character in the New England portion of the Appalachian system will be evident from what has been here stated. This region is marked by comparatively low swells of ground, on which rise groups of higher points, rather irregularly distributed, nowhere reaching the limit of perpetual snow, and nowhere presenting great obstacle to internal communication.

The geological structure of this north-eastern prolongation of the Appalachian system has been as yet only imperfectly made out, a circumstance due in part to the extreme scarcity of fossil remains, and in part also to the fact that the various sedimentary beds have been so metamorphosed as to be distinguishable only with great difficulty from the associated eruptive formations, while even the latter have frequently been themselves so much changed by chemical action, since their appearance at the surface, that it is only by the microscope that their real nature can be made out.

With the exception of a narrow belt of Mesozoic rocks in the Connecticut valley and a small basin of similar age in Woodbury and Southbury, Connecticut, and also with the exception of a very limited set of deposits of late Tertiary age on the eastern boundary of Lake Champlain and on the Atlantic coast, there are, so far as known, no rocks in New England more recent than the Palaeozoic. Tertiary and Cretaceous formations are, however, found covering small areas on some of the islands adjacent to the coast. Along the western sides of Vermont and Massachusetts the rocks are clearly proved by their fossils to be of Lower Silurian age, and their structure has been made out in part. There are faults and synclinals, - limestones and chloritic and talcose slates being the predominating rocks. The dips are chiefly to the eastward, and the rocks are of more recent age as we go east from Lake Champlain, on the east side of which is a large development of the Potsdam sandstone. In and near the Connecticut valley, to the east of the region just noticed, fossils have been found (at Bernardston, Mass.) of late Upper Silurian age (Helderbeg of the New York Survey). The stratigraphical relations of these rocks, however, remain obscure. The same may be said of nearly or quite all of New Hampshire, of eastern Massachusetts, and of a large part of Maine. At one point in New Hampshire (Littleton) fossils have been obtained of the same age as those discovered at Bernadston. In northern Maine, traversing the State in a wide belt running northeast and south-west rocks occur of Upper Silurian and Lower Devonian age, well characterized by fossils, a part of this belt being clearly identical in age with the Oriskany sandstone of the New York Survey. The stratigraphical relations of these rocks are still obscure, and south of this fossiliferous belt is a wide area in which no fossils have yet been found. At one point in Massachusetts (Braintree, near Boston) more than fifty years ago fossils of the lowest Silurian age (Primordial) were found, and there are other indications that the rocks near the coast of New England, from Cape Cod north, are very low down in the fossiliferous series; but in Massachusetts, as well as in New Hampshire and Maine, there is a wide area between the Devonian and Upper Silurian rocks of the Connecticut valley and northern central Maine, of the geological age of which nothing is definitely known, and of which the stratigraphical relations are still very obscure.

To the west and south-west of the Hudson river, in New York, the intricacy and obscurity of the orographic structure and geological age of the Appalachian system begin to be cleared up; but it is not until we reach Pennsylvania that the characteristic features of this range are fully developed. (1) The first of these its, along its south-eastern edge, as we cross the system from south-east to north-west, at right angles to its trend, a series of elevation, at first comparatively unimportant and more or less detached from each other, but gradually, in going in a south-westerly direction, becoming more and more prominent and continuous, until towards the extreme southerly end of the system, it forms the most imposing connected mass of high plateaus and still higher ridges anywhere exhibited in the Appalachian region. This south-easterly division of the system has no single distinguishing appellation. It is called inPennsylvania the South Mountains, in Virginia the Blue Ridge; and in North Carolina and Tennessee it has various names applied to its different portions. (2) The second important feature is the Appalachian region proper of the First Pennsylvania Survey a region of wave-like folds or corrugations not so metamorphosed but that the geological sequence can be distinctly made out, in which orographic disturbances and a peculiar erosion have developed an interesting and intricate topography. (3) The third region, in crossing the chain from south-east to north-west, is that of plateaus, bounded on the south-east by an escarpment to which the name of Alleghany has been frequently given, and by which that portion of the system which lies in Pennsylvania is still almost universally known. These are the three most prominent divisions of the system south-west of the Hudson, and between the first and second there is a pretty well marked depression which is a very conspicuous feature of the topography in Virginia and Tennessee (in Pennsylvania the Kittatinny, in Virginia the Great Valley, and farther south the valley of East Tennessee).

We next come to consider the region occupied by south-eastern New York and northern New Jersey. The Green Mountains are generally considered as being prolonged south-westwardly in the Hudson river highlands and the highland range of New Jersey. This latter range in New Jersey occupies a belt of country somewhat over 20 miles in width on the New York line, but narrows down to less than half that on the Delaware. It includes no long unbroken ridges, the one which comes nearest to having this character being the Green Pond range, about 12 miles long; nor are the subordinate ridges of which it is composed in a line with each other or with their axis parallel to the direction of the main range. The highest point is Rutherford’s Hill (1488 feet). The Kittatinny valley mentioned above is distinctly marked in New Jersey, where is also bears the same name. It is bounded on the north-west by a range called the Shawangunk in New York, the Blue Mountains in New Jersey, and the Kittatinny in Pennsylvania. It lies on the extreme north-western edge of New Jersey, and forms an almost unbroken straight line for about 40 miles within this State, from the Delaware Water Gap to the New York line. The straightness of this ridge and its almost level crest, from 1200 to 1800 feet in height, mark it as belonging to the peculiar topographical belt of the Appalachian system which occupies central Pennsylvania. This belts is distinctly recognizable still farther east, in the vicinity of Catskill and east of he mountains of that name where there is a miniature group of hills, called the Little Mountains, only a mile or two in width, and but a few hundred feet in height, which are made up of rocks of the same geological age as those in the central division of the Pennsylvania Appalachians, and with the same characteristic structure.

The plateau region occupies a large portion of the State of New York. Its northern edge extends along the south side of the Mohawk river, forming a distinctly marked escarpment (the Heidelberg Mountains). Farther west, in central New York, only a few miles from the central depression through which pass the Erie Canal and the great lines of railroad connection Albany with the west, are various heights rising 1000 feet above the surrounding plateau, and from 1600 to 2000 feet above the sea (Fenner Hill, in Madison county, 1862 feet; Ripley Hill, in Onondaga, 1968; Niles, in Cayuga, 1623; Milo Hill, in Yates, 1343; and East Hill, ion Oswego, 2300). This plateau, with its extension to the southwest into Pennsylvania, forms the highlands in which rise the various branches of the Susquehanna, which traverses the entire Appalachian system in a general direction from north-west to south-east.

In south-eastern New York there is a remarkable group of mountains, very conspicuous from the Hudson, and apparently quite isolated as seen from the eastern side, but which, as approached from the west, are recognized as being in intimate connection with the plateau region of central New York. This group is known as the Catskills, of which there are two divisions.- the northern, or Catskills proper, and the southern. The Catskills proper are a massive plateau, enclosed between the Esopus and Catskill creeks – affluent of the Hudson running in a south-easterly direction, nearly parallel with each other, and at a distance of about 25 miles apart. The mountain mass thus enclosed consists essentially of two border chains running parallel with the two streams, and from 10 to 15 miles apart. The highest point of the north-eastern border is the Black Dome, 4002 feet; that of the south-eastern range, Hunter Mountain 4038 feet. The southern group, lying south of the Esopus, the drainage of which on the west and south-west is into the Delaware river, includes Slide Mountain, the highest point of the entire Catskill group (4205 feet).

The Catskill range is, like the plateau region generally, of the Devonian and Lower carboniferous formations. The upper 500 feet of the Slide Mountain is occupied by a cap of the carboniferous conglomerate, the equivalent of the millstone grit, and the nearest approach to the Coal-measures in any part of the New York.

From New Jersey southward the Appalachian system is very easily separated into those divisions which have already been indicated. Its eastern border-the Atlantic slope-is an area of land in rising gradually from the sea towards the interior, to the foot of the Appalachian ranges, broadening out as we follow it southward, and at the same time acquiring a greater elevation before the mountains are reached. This gently rising area is hardly perceptible in New England, but it occupies a considerable portion of the Atlantic States from New Jersey south to Florida. Its altitude at the eastern base of mountains is, in Pennsylvania, only from 100 to 300 feet, - Lancaster and Harrisburg, which are on its western border, being respectively 350 and 320 feet. On James river, in Virginia, it is about 500 feet high (Lynchburg, 529 feet), but at the source of the Catawba it has risen to 1200 feet. This region of comparatively low elevation is geologically, and also to a certain extent topographically, made up of two quite distinct portions. The part nearest the coast is almost flat, or with the gentlest possible slope seaward, and unbroken by any elevations worthy of notice. Beyond this belt, to the west and north-west, is another itself, almost a plain, but more undulating rising more rapidly westward, so as to form almost a tableland at the base of the mountains, and itself diversified, in its western portion, by elevations which in places rise high enough to be called mountains. The belt nearest the shore consists of Tertiary and Cretaceous rocks having a very gentle did seaward. These are first met with, as we proceed southward, on Raritan Bay, where the belt occupied by them is from 20 to 25 miles wide, but on reaching Philadelphia it is found to have acquired a breadth of more than 50. The stratified mass in New Jersey consists of a great number of alternations of sands, marls, and clays, from a third to half the width of the belt being occupied on the surface by the Cretaceous, and the more eastern portion being of Tertiary age. Trenton, near the western edge of this belt, is only 33 feet above the sea-level. These newer formations are of special interest on account of their fossils, and because of their great economic value. This level belt of newer rocks maintains its width through Delaware and Virginia, and attains a width of more than 100 miles in North Carolina and Georgia. Between New Jersey and North Carolina it is deeply intersected by bays, the heads of which approximately mark a change from rocks of recent age to those much lower down in the series, which make up the western portion of the Atlantic slope. This change is also most distinctly marked by an interruption to the navigability of the rivers, and it also manifests itself in the position of the cities of the Atlantic slope, most of which to the south of New York (Trenton, Philadelphia Baltimore, Washington, Richmond, Petersburg, Raleigh, Columbia, Augusta, Milledgeville, and Montgomery) are not on the Atlantic itself, but on or very near this geological break. From Virginia southward the coast is very little indented, and most of the large towns are at a considerable distance from it. In North Carolina the slope of the coast belt-here 100 miles wide – is hardly more than 1 or 2 feet to the mile. It is occupied by nearly horizontal strata of Tertiary, overlain in considerable part by detrital accumulations of still later age, the whole consisting of loose sands, clays, marls, and gravels irregularly piled one aboveanother. Nearly the same may be said of the continuation of this belt through South Carolina and Georgia. In the former State Columbia (between 200 and 300 feet above the sea) marks its western border. In Georgia, at the general level of the country, nearly the whole belt is Tertiary; but the underlying Cretaceous is revealed in various places where the rivers have cut deeper than usual. The heights of the cities are as follows: - Augusta, 130-180 feet; Milledgeville, 310; Macon, 334 feet.

The second or upper belt of the Atlantic slope is in large part made up of rocks which are destitute of fossils, and in regard to which it has not yet been clearly made out whether they are really stratified beds older than the lowest Silurian (Azoic or Archean of Dana), or whether they are highly altered rocks of Palaeozoic age. Over most of its area it has very distinctly the character of a plain. Pennsylvania it is highly cultivated and densely peopled, a "country of rolling hills and gently-sloping vales, with occasional rocky dells of no great depths, and nowhere more than 600 or 700 feet above the seal-level. It is bordered on the north-west, for a portion of its extent, by a low range of elevations, known as the South Mountains, and generally considered to be the northern prolongation of the Blue Ridge of Virginia and the States farther south. The South Mountains enter Pennsylvania at the Delaware, forming a region of irregularly grouped ridges, which occupy a breadth of somewhat less than 10 miles, and which do not rise to an elevation of more than 400 to 500 feet above the valleys. These hills are made up of massive varieties of gneiss, sandstones, - recognized by the Pennsylvania Survey as being of Potsdam age, - and Lower Siluranin limestones. The valleys resting on this latter rock are covered with a highly fertile soil. In Virginia the upper belt of the Atlantic slope broadens out and becomes more and more complicated in its topography. In an official report this region is divided into three portions, called the Middle, Piedmont, and Blue Ridge divisions of the State. The Middle division is said to extend westward from the sea to the foot of the low broken ranges which, under the names of Kitoctin, or Kittoctan, Bull Run Yew, Clark’s South-West, carter’s, Green, Findlay’s, Buffalo, Chandler’s, Smith’s, &c., Mountains and Hills, extend across the State south-west from Fairfax country on the Potomac to Pittysylvania county on the North Carolina line. These broken ranges, which preserve a general parallelism with the Appalachian ranges proper, and form, as it were, the outliers of this system, are designated by Major Hotcjkiss the Atlantic Coast range. This middle country is described as a moderately undulating plain, from 25 to 100 miles wide, and rising from the south-eastern border, where it is from 150 to 200 feet above the sea, to an altitude of from 300 to 500 feet along its north-western edge. It is a succession of low north-east and south-west trending ridges, the valleys between them being sometimes narrow and deep, but the ridges themselves not very prominent. The rocks are metamorphic slates and gneiss, with numerous eruptive masses in the form of dikes, and with many quartz veins, some of which contain considerable gold, although mining has not, on the whole, been successful. The Peidmonth division forms a belt of from 20 to 30 miles in width, and may properly be considered as being the foothill border of the Blue Ridge itself. There is a marked tendency to the formation of a continuous valley between the broken ridges already noticed as forming the so-called Coast range and the Blue Ridge proper. In this valley lie Culpeper (400-500 feet), Fairfax (382), Charlottesville (450), Lynchburg (650), and other towns. This foothill region is described as exceedingly intricate. The coast range is succeeded, in the west, by numberless valleys of all imaginable forms, which extend across to, and far into, the Blue Ridge, to which, in point f fact, they topographical belong. Portions of the Piedmonth country, however, form quite extensive plains.

The Blue Ridge with its belt of foot-hills- the Piedmont region- forms a conspicuous feature of the topography of Virginia and the States farther south. The Potomac breaks through it at Harper’s Ferry, at an elevation of 242 feet, the mountains adjacent rising about 1200 feet higher. The passes, locally known as "gaps," are numerous, and several of them are traversed by railroads. The James river intersects the Blue Ridge 706 feet above the sea. The elevation of this range is considerable, even in its northern portion,-Mount Marshall, near Front Royal and Manassas Gap, being about 3370 feet. The heights as well as the breadth of the range increased rapidly as the southern line of Virginia is approached, - the Peaks of Otter, in Bedford county, near Buford’s Gap, rising to 4000 feet, and Balsam Mountain, just at the North Carolina line, to 5700 feet. Here the Blue Ridge has already begun to expand into that wide and high plateau, occupying the western portion of North Carolina, in which are found the highest points of the entire Appalachian system. This elevated region is formed by a broadening out and bifurcation of the Blue Ridge, which begins near Christiansburg (2012 feet), opposite the point where the New river changes its course from a direction parallel with that of the Appalachian ranges to one at right angles to this, and breaks through that part of the system which lies north-west of the Great Valley, flowing in that direction to the Ohio. This plateau rises in North Carolina to an average height of 2500 feet, white portions of its are over 3500. It is about 150 miles in length, with a width varying from 15 to 50 miles and averaging about 30, and reaches its highest altitude (3500-4000 feet) at its narrowest part. The plateau is bordered by broken ranges; that on the south-east still continues to be called Blue Ridge; the more or less continuous line of elevations in the south-west has various names – Unaka, Smoky, Bald, and Iron being among the number. Between these exterior ridges run various spurs, with many points over 6000 feet, the culminating one being the Black Dome (6707 feet). The northern portion of this high region is drained by the head waters of the New river, but the principal drainage of the most elevated parts is to the north-west, from the plateau, through gaps in the western ridges, to the Tennessee.

The geology of the Blue Ridge division of the Appalachian system is obscure and difficult. Most of the rocks are highly crystalline, but whether or Palaeozoic or Azoic age is as yet undecided. These crystalline rocks are more or less intersected by ancient eruptive masses, the range and extent of which are uncertain. Flanking the Blue Ridge on the west side, and involved in the disturbances of the strata by which it has been built up, are sandstones and limestones which in Pennsylvania have been recognized as being of Lower Silurian age. These limestones seem to become more arenaceous farther south, and also to become unfossiliferous. It may be assumed, however, that the range in general is made up of rocks not newer than Lower Silurian.

To the west and north-west of the Blue Ridge division of the Appalachian system lies the Great Valley. Its north-western limit in Pennsylvania is the Kittatinny Mountain, which separates it from the mountain district lying adjacent to it on that side by a very regular natural wall. The entire length of the valley in that State is about 165 miles, and its width between 10 and 11 miles. Throughout its whole extent it presents a gently undulating surface, approximating to a level plain, with here and there a belt of low hills. In Virginia the Great Valley is a very important feature, having a length of a little over 300 miles, and a quite uniform width of about 20. The mountains on its north-west side (the Kittatiny) are known by a variety of names, their northern portion being designated on some maps as the Great North Mountains. A small portion of this valley is also included within the limits of West Virginia. The drainage of the Great Valley is complicated. The north-eastern portion is the beautiful and fertile valley (about 140 miles in length) of the Shenandoah, drained by two parallel branches of that river,- a well-marked double range, 50 miles in length, dividing the Great Valley longitudinally. Through this range the northern branch of the Shenanadoah breaks, turning at right angles to its former course and uniting with the southern branch at Manassas Gap, below which, towards the Potomac, the valley is but slightly broken by hills. South of that portion of the Great Valley drained by the Shenandoah is a region about 50 miles in length, in which are the head waters of the James. The various branches of this river, coming from north-west and south, unite at the western base of the Blue Ridge, and there break through it. The remaining portion of the valley belongs partly to the Roanoke and aprtly to the New or Kanawha and to the Holston. The rise of the Great Valley to the south-west is very marked, the point where the Shenndoah enters the Potomac being only 240 feet above the sea, while the head of the head of the New river is in a region ranging from 2500 to 3000 feet. According to the official report, "the aspect of this region is singularly pleasant. The great width of the valley, the singular coloring and wavy but hold outline of the Blue Ridge, the long uniform lines of the Kittatinny Mountains and the high knobs that rise up behind them in the distance, the detached ranges that often extend for many miles in this valley, like huge lines of fortifications- all these for the outline, filled up with park-like forests, well-cultivated farms, built towns, and threaded by bright and abounding rivers, make this a charming and inviting region.

The next division of the Appalachians, which may be called the middle belt, is perhaps the most interesting and peculiar although not the most persistent portion of the system. It is not until Pennsylvania is reached that it becomes important. Its character of this division is thus indicated by H. D. Rogers in the report of the First Geological Survey of that State; _ "It is a complex chain of long, narrow, very level mountain ridges, separated by long, narrow, parallel valleys. These ridges sometimes end abruptly in swelling knobs and sometimes taper off in long slender points. Their slopes are singularly uniform, being in many cases unvaried by ravine or gully for many miles; in other instances they are trenched at equal intervals with great regularity. Their crests are fort the most part sharp, and they preserve an extraordinarily equable elevation, being only here and there interrupted by notches or gaps, which sometimes descend to the water-level, so as to give passage to the rivers. The whole range is the combined result of an elevation of the strata in long, slender, parallel ridges, wavelike in form, and of excessive erosion of them by water; and the present configuration of the surface is one which demonstrates that a remarkable, and as yet little understood, series of geological events has been concerned in their formation. The ridges, which are but remnants of the eroded strata, are variously arranged in groups with long narrow crests, some of which preserve a remarkable straightness for great distances, while others bend with a prolonged and regular sweep. In many instances two narrow contiguous parallel mountain crests unite at their extremities, and enclose a narrow oval valley, which with its sharp mountain sides bears not unfrequently a marked resemblance to a long slender sharp-pointed canoe." The system of ranges thus described crosses northwestern Maryland, and is largely developed in Virginia, with characters in many respects resembling those which it displays farther north. It is a region of long, narrow, parallel valleys, separated by narrow, straight, and quite elevated ridges, of which no one rises greatly above the others. The number of these diminishes as we proceed in a south-westerly direction, and the belt narrows in proportion. The drainage on the extreme eastern borer is into the Great Valley. The interior valleys in the northern half of the belt are traversed streams flowing into the Potomac; the southern half is mostly drained by branches of New river. In some cases the waters flow towards a central depression in the valley, and then break through the enclosing range. The rocks are Silurian, Devonian, and Lower Carboniferous. In its north-eastern extension this division includes the anthracite region of Pennsylvania. The ridges by which the Appalachian belt proper is traversed are the result of a series of flexures of the strata, along numerous axes of elevation and depression, not complicated in Pennsylvania by extensive dislocations of the crust, or faults, either longitudinal or transverse, but gradually becoming so as we proceed towards the south-wet. It is a curious fact that, in following in a south-westerly direction the Appalchian belt proper, we find that it disappears or merges in the Great Valley, which in Tennessee occupies the entire space between the Blue Ridge and the Alleghany plateau, there called Cumberland tableland, and is fully 40 miles in width. The rocks which underlie the Great Valley are of the same geological age as those of which the Appalachian belt is composed farther north, but more closely compressed together, and complicated by great longitudinal faults, the whole area being comparatively depressed one, and not broken by marked ridges. The true Appalchian belt is therefore limited to Pennsylvania, Virginia and a very narrow space in Maryland, and here the system has its greater width and most intricate and interesting topographical features, but not its highest elevations, which occur north and south of this portion, in regions of greater and more irregular disturbance, complicated by metamorphic changes and irregular intrusions of eruptive material on a grand scale, making the task of unraveling the geological structure extremely difficult.

The most western member of the Appalachian system- the plateau-is the one of which the geology is most easily made out, and, while its eastern borer is an important topographical feature it merges so gradually in the great central or Mississippi valley, that any definite of its limits in that direction is quite impossible. The position and elevation of this plateau region in New York have been already indicated. Farther south this tableland occupies the western portion of Pennsylvania, nearly all West Virginia, a part of Kentucky and also of Tennessee, in which latter State it is called the Cumberland tableland, or the Cumberland Mountains, since it here presents itself exceptionally with abrupt edges on the west, as well as one the east, but it is narrowed down to a width of not more than 30 or 40 miles in the northern portion of the State and of much less in the southern. The bold escarpment with which the plateau faces the east in Pennsylvania is known as the Alleghany Mountains. It is continued in Virginia, but with much less distinctness. It is from this tableland that the waters of the Susquehanna descend to the Atlantic, crossing the entire Appalachian system in its course, while with the New river the condition of things is reversed, since this stream heads on the eastern edge of the range and flows across it in the opposite direction from that of the Susquehanna.

Since the dip of the strata in southern New York and western Pennsylvania is generally to the southward, newer rocks occupy the surface as we proceed in that direction. The Coal-measure appear soon after the line of division of these two States is passed, and it is largely with rocks of this age that the tableland is covered through the whole of its southern extension. In fact the Appalachian coalfield, as it is called, presents an almost continuous mass of coal-bearing strata, extending from northern Pennsylvania to Alabama. A part of this field, however, notably in Ohio, reaches far beyond the topographical limits of the Appalachian region.

The Appalachian tableland is, even in Pennsylvania, not entirely destitute of marked topographical features. The axes which characterize the system farther east are not wanting, but the strata are raised and depressed by gentle undulations, and not broken by precipitous ridges. Much intricacy is given to the topography, in a small way, by the streams cutting down into the soft rocks.

Before leaving the Appalachian region it will be desirable to add a few words on the belt of Mesozoic rocks occurring on the Atlantic slope, which, although not forming a prominent topographical feature, are of much geological and palaeontological interest. This belt consists chiefly of sandstones of reddish-brown color, with which are associated shales, and occasionally, especially in the lower portion, coarser materials- conglomerates, - which are sometimes well rounded by water, but in places almost breccia-like in character. These rocks are first seen, on the north-east in New Brunswick, in Nova Scotia, and on Prince Edward Island. In New England they are limited to the valley of the Connecticut river, with a small parallel area a little to the west of this in the towns of Southbury and Woodbury, Connecticut. The Connecticut valley Mesozoic area is about 150 miles in length, with a maximum breadth of about 14. The largest belt, however, is that extending from the west side of the Hudson river, along the south-eastern side of the South Mountains and Blue Ridge, through New Jersey, Pennsylvania, and Maryland, to about the center of Virginia, having a maximum width of about 30 miles and a length of somewhat over 300. There are other smaller areas of the same rock in Virginia and in North Carolina, - that of the last-named State extending a short distance into South Carolina. Associated with this sandstone is a considerable amount of igneous rock, which occurs in the form of dikes and overflows, which, as the sandstone has been worn away by erosive agencies, occasionally stand out quite conspicuously, although nowhere reaching an elevation of more than a few hundred feet. Some well-known and much visited localities, such as Mount Tom and Mount Holyoke in Massachussetts, the hanging Hills and East and West Rocks in Connecticut, and the Palisades in New York, are of this character. The fossils which the sandstones contain are not numerous, but are of much interest, and the geological age assigned to this formation by most palaeontologists is the Triassic. In several localities, however, great numbers of footprints of animals occur, which were long considered to be those of birds, but are now known to belong-in considerable part, at least – to the Reptilia, some of which had certain features allying them to birds. The paucity of fossil remains, other than footprints, found in these rocks has rendered the working out of their true relations a matter of considerable difficulty. The latest investigations of Prof. Fontaine show that the Mesozoic areas of Virginia are separable into two quite distinct groups, an older and a newer, the floras of the two being quite different. It is in the older Mesozoic of Virginia, and in the most easterly area, near Richmond, that the coal occurs which was the first worked in the United States. The stratigraphical relations of the Mesozoic sandstones are difficult of comprehension, and have been the occasion of much discussion.

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