The Isle of Man is naturally divided into two distinct portions, as dissimilar in their general appearance as in their structure; the southern, and by far the larger part, consisting of an irregular group of mountainous land, and the northern, presenting an alluvial tract, for the most part flat, and in many places so level as to admit with difficulty of a sufficient drainage for the purposes of agriculture. The characters of the shores correspond, as might be expected, with that of the surface. The principal masses have thus slid into new positions, while many smaller fragments appear still suspended in very act of falling; even the larger, seeming to be often so nicely poised that the hand would almost be thought sufficient to push them from their present situation into the sea that rolls below.
Pleasing scenes, rarely such as can be styled picturesque, occur every where in these sheltered valleys; and when, in the progress of time, wood shall become more predominant, the Isle of Man will, yield little in beauty to those parts of England or Scotland which are not characterized by the striking features of Cumberland and the Highland districts, or the extended magnificence of Kent and Somersetshire.
These distinct characters have doubtless been produced by some difference in the present and former action of the tides on those shores, which it would neither be very easy, nor perhaps very useful, to ascertain. The natural consequence of such a varying action is a variation of the sea-line boundary, which appears however to be of little moment; while, at the same time, it is far too common a phenomenon in similar cases to require particular notice. From Ramsey to Douglas the eastern shore is rocky, with no exception but that of the sandy tract in Douglas bay. The cliffs are generally high and abrupt, and the sea in most instances skirts their bases, seldom allowing. access to the shore for boats, except in the few places where creeks are found at the mouths of the small streams that flow down the eastern declivity of the mountain land.
In a physical view, the phenomenon is however much too common to require any explanation; while it is obviously a slide of no very distant origin, geologically considered. As an historical occurrence, it is of considerable antiquity; and although the distance in point of time cannot be ascertained, its lowest limit is recorded by the existence of a Druidical structure on one of the moved fragments; a chronological index, at least very remote, if not exactly to be assigned.; The narrow and rocky channel which separates the Calf from the main island, with the boisterous tide that runs through it, and the high rocky shores that extend from this point to Brada head, will present much interesting scenery to those who may examine them from below although from above, the points of sight are seldom picturesqiue Hence to Peel, the same character, but with less grandeur, is preserved; after which, lower and less striking rocks, of different aspects, continue with some interruption to skirt the shore till the mountain land terminates in the alluvial tract already described. The castle of Peel, more conspicuous for the extent and variety of its outline, than for the magnitude and style of its buildings, with the picturesque situation of its harbour and town, and the life produced by its shipping, forms an interesting object wherever it is visible in following this line of coast.
The view from the summit of Snaefell is remarked for including the several parts of the British dominions; the ranges of Snowdon and of Cumberland being visible to the eastward and southward, the mountains of Morne, and Fairhead appearing on the west side, and the Mull of Galloway with the elevation of Criffel rising in the northern horizon. From the summit of Snaefell, which is the principal elevation of the Isle of Man, a tolerably accurate idea may be formed of the general distribution of the mountains, and of the relations of the several parts of the group. The forms of the mountains are invariably rounded and tame, as is most frequently the case in the schistose districts of Wales and Cumberland, and the rock is very rarely seen protruding so as to form abrupt faces; never in such a way as to give a rugged outline on the sky. On the north-eastern side of the island, the descent appears indeed more rapid than on the other parts of the group; and the difference is very remarkable if we compare the declivity which lies between Laxey and Ramsey, and includes St. Maughold’s head, with that which descends towards Douglas, Peel, or Castle Town. In consequence of the gentle slope of this elevated land, the mountains are, as might be expected, wet and boggy; a covering of peat, amounting on an average to two feet in depth, appearing to invest most parts of the elevated region.
The positions and directions of hills, and more particularly of those which consist of stratified rocks, whether primary or secondary, and the relations which these bear in their several parts to the original positions of the strata, form an important question in physical geography. The few trees which are to be found in the island, are to be seen chiefly in these valleys; and, thus sheltered, they thrive as well as in other similar situations on the western coasts of England.
From this disposition of the land, the RIVERS of.the Isle of Man are, as might be expected, rather numerous than extensive in their courses. Every small valley produces some stream, discharging itself into the sea or increasing the strength of some neighbouring river. Many of them are consequently too small to require notice, although from the prevailing moisture of the climate, they are rarely dried up. The altitude of the mountain land is sufficient to intercept the track of the clouds during the greater part of the yeare; while its western position and insular situation ensure an almost constant supply of rain.
The principal river of the island rises by numerous branches from the declivities which surround Snaefell, and passing in a tortuous course by Sulby, is discharged into the sea at Ramsey. The Bright river, which joins the Blackwater to form the inlet at Douglas, the rivers of Castletown, of Peel, of Laxey, and the Santon, which marks the boundary of the limestone district on the eastern side, are the next most remarkable streams; but like the smaller, which it is unnecessary indeed even to enumerate, they require no particular description. It is more probable that the alluvium in question has been the result of a general diluvian action, directed from the south towards the north, nearly in the present line of the channel which separates England from Ireland.
Sensible alterations are now taking place in the submarine banks which occupy the western channel between this island and England; and as a new one appears to be in the act of forming, according to the reports of those who navigate these seas, similar actions may have changed the general shape and outline of this alluvial tract from what it originally was, and may hereafter effect in it further alterations. It was with a view to the position of this alluvium, indicating a current to the north-wards, that a doubt was expressed respecting the diluvian origin of the deposits which occupy the interior valleys.
The rivers of this island have little power, and do not appear to have been concerned in effecting the present irregularities, which are more easily referred to the same distant but unknown operations by which the mountains themselves assumed their existing disposition. In a few instances, and perhaps most remarkably at Laxey, from the steepness of the declivity and the rapidity of the water, a quantity of rubbish, forming a beach of rounded pebbles, has been accumulated at the mouths of the streams : but it is generally insignificant in extent; making no permanent addition to the land, and producing no effect in changing the forms of the shores at the exits of the water. The operations of the mountain streams in some situations, and among others in the higher parts of Baldwin valley, upon the mountain alluvia, is rather more remarkable; since they are in these places skirted by the flat terraces of rubbish which so often accompany the course of a river that cuts its way through these accurnulations of loose materials.
These alluvia are found on the lower parts of the slopes of the hills and in the bottoms of the valleys, all over the island. Their origin cannot apparently be traced, either to the present or former action of rivers; since they are equally deep and predominant even where water could never have flowed. Nor is there much evidence of a diluvian origin, a cause, the operations of which are so frequently to be traced in the mountainous parts of Scotland as well as on the great plains of England.
The presence of granite and porphyry in this alluvium, substances scarcely existing in the island, prove that they have been brought from distant points. If even any imaginary former altitude of the present mountains be assumed, the well known laws which predominate with respect to the relative positions of rocks, do not permit us to assign a place for the granite whence the granitic fragments should be derived, had they resulted from the decomposition of former mountains existing in the island.