[From Isle of Man, Cumming 1848]
Ancient legend of the Isle of Man - allegorical of its early history. - The interest which may be excited by the study of the physical history of a country. - General statement of the physical changes which have passed over the Isle of Man. - Geology not a mere speculative science, but an enunciation of established facts.First view of the Isle of Man. - Erroneous impression as to its size ; how produced. - Its varying appearance as presented at different points of the compass. - This variety produced by the varied action of certain physical causes - The great natural agents which have modified the crust of the earth. - The records of the Palaeozoic period in the Isle of Man. - Great gap between it and the Tertiary, as there developed - The glacial epoch. - The more recent physical changes and present character of the Island.
THE earliest native history of the Isle of Man is of a legendary character. It was thrown into the form of a popular ballad in the sixteenth century 1. It derives the name of the Island from Mannanan-beg-mac-y-Lheirr (little Mannanan son of Lheirr), an ancient king and famous necromancer, who is said to have preserved his kingdom from foreign invasion by the exercise of his magic art. At his bidding, the mountains rocked from their foundation, the sea boiled up from its lowest depths, volcanic fires, with sulphurous vapours and dense columns of smoke shot forth, and thick mists enveloped the Isle in an impenetrable mantle 2.
It may be permitted us, perhaps, to regard this strange legend simply as allegorical of the confusion and obscurity belonging to the early history of the Isle of Man, looming forth from a dark chaos, enveloped in thick mists of uncertainty and error.
There is however a history of the Isle far more ancient than any to which human archives can give access, a history inscribed on stone in ever-enduring characters by the finger of Him that was, and is, and is to come, upon which such darkness and uncertainty does not rest : this is its physical history. And to those who have the patience to study, and some earnest desire to make themselves masters of its various chapters, it will certainly be found by far the most interesting and instructive.
The wonders of necromancy which the legend unfolds have nothing to offer in comparison with the stupendous realities which the geologist is permitted to read out from the book of nature; a volume ample and highly illustrated; a volume, upon which when He looked on the day when it came forth fresh from His hands, and ere yet it was marred and blotted by man's sin, its great Maker pronounced very good.
The antiquary of the world turns to that chapter in its physical history which has reference to the Isle of Man, and he finds testimony given, in language which it is impossible to misunderstand, to the fact that it has been the scene of mighty events ; that it too, small as it may seem, has been (so to speak) the battle-field of the elements; that fire and water, heat and cold, have here met together and exhausted their fury, and have left behind their either entombed under gigantic mounds, or scattered far and wide over its naked surface, the tokens of their power, the fragments of their armour, and the skeletons of their hosts. He can produce evidence from this book to show that at one period the island heaved and tossed to and fro on a sea of molten lava, which poured forth over its surface through the rents formed during a time of convulsion, whilst volcanic ashes darkened the air, or buried, as in a living sepulchre, the inhabitants of the neighbouring seas. He can show that at another period vast waves desolated its fair surface, tearing up in their course the very rocks themselves, and depositing masses of granite on the highest mountain-tops. At one time he reads of a tropical climate with its luxuriant vegetation of lofty palms and towering tree-ferns adorning the land, whilst the sea around teemed with tropical life, the ever-active coral insect filling up the depths with its calcareous and many-coloured secretions, and the delicate nautilus plowing the sunny surface of the waters, and spreading forth its tiny sail to the genial influence of the primæval trade-wind. But time hurries on and hurries away all these fair seasons in its course, and he reads again how arctic storms ravaged the coasts of the lovely isle, whilst an icy ocean girt it round, lashed its promontories and graved its shores with the weight of icebergs.
The geologist beyond doubt brings strange things to our ears, and he has so constant a habit of speaking disrespectful words concerning the age of our parent Earth, that no wonder if many of her dutiful children are offended at his statements, and some should affirm that he is wilfully uttering what he knows to be false.
And yet geology, rightly viewed, is no mere speculative science. It has for its object to discover and, if possible, classify facts, and by the strictest principles of analogy, to trace out the cause in the effect. In this latter branch it may happen that an insufficiency of data shall impart a measure of uncertainty to the argument as to cause; nevertheless these data are individual certainties in the mind of the geologist, and his real object (if sincerely devoted to his science) will henceforward be to search for phænomena additional to those already possessed, and not to discard as useless what he is already assured of, because it will not fully support him in the enunciation of causes which he deems only probable. And it is highly desirable that all who read a book which has to do with the structure of the earth or any part of it, should first of all be assured of the reality of the science on which the geologist is intent, and the soundness of those principles on which he claims the assent of his hearers or readers to the statements which he has to set before them.
I remember with a feeling of melancholy pleasure the first glimpse which I caught of the Isle of Man. It was from the summit of Helvellyn, which, though not the loftiest of the Cumberland mountains, presents views unrivalled by airy of them. By my side stood a friend, an ardent an admirer of nature's beauties as myself, and who, in company with the devoted metropolitan of India, has since had opportunity enough of studying them in all the variety which the three presidencies of that mighty empire unfold, and who, almost alone and on foot, has penetrated into the heart of the Himalayah chain, and contemplated her grander features in the midst of habiliments of snow. The day had been one of storm and cloud, and promising no repayment for the toil of the ascent. All at once the dense canopy which rested on the mountain seemed lifted up, and underneath it the scenery, in an atmosphere cleared by the recent tempest, came forth in its most impressive magnificence for miles around. After dwelling awhile in silent admiration on the sterner beauties of the nearer landscape, our eyes rested on the westerly sea, and there in the glory of a setting sun, floating as it seemed most tranquilly on the bosom of the great deep, lay the Isle of Man.
The peculiar form of the island 3 causes it to lose in apparent magnitude when seen from a distance (especially from the sea) in a greater degree than is produced optically by simply receding from an object. The reason is this : the northern portion of the island is an almost plane area of nearly fifty square miles, of which the greater portion (and that portion more especially which is close upon the northern extremity of the mountain range) is elevated hardly more than sixty feet above the level of the sea. In receding therefore from the island, this area very soon sinks below the horizon, and the length of it is suddenly shortened by six miles when viewed from the south-east or north-west. Again, the more elevated portion shows very different phases as approached from different points. The distant northern view 4 is that of an abrupt pile of mountain rent into chasms, which the nearer approach shows us as lovely glens,- Ravensdale, Sulby Glen, Glenahlyn and Ballure. The western view is an extended mountain chain descending rapidly to the sea on the nearer side, more distinctly precipitous at the south-western extremity, and crossed at right angles by two valleys at Port Erin and Peel, by which the island appears divided into three. The southern view exhibits a gradual slope from the sea-level to the highest points with no distinct valleys or chasms, but occupied by towns, villages, villas, cottages, corn-fields and pastures. The eastern view shows rocky cliffs and bold headlands from 300 to 400 feet high, backed at the distance of seven or eight miles with mountains ranging from 1500 to 2000 feet above the sea, between which and the cliffs the slope is generally easy and clothed with verdant pasture. Now all these various appearances of the same mass, as viewed from different points, are in reality due to certain ancient agencies which it is one of the chief objects of the physical history of the Isle of Man to trace out, to classify and describe. It may be well, for the benefit of non-geologists, to state in this place a few of the leading truths of geology to which constant reference must be made.
There are evidently two prime agents always at work modifying the crust of the globe on which we tread, i. e. water and fire. The former has a constant tendency to lower the more elevated portions, by carrying down particle after particle and mechanically depositing them in the hollows, which would thus become ultimately filled up, and the whole surface of the earth be reduced to a plane; the latter helps to consolidate and harden into rocks 5 the soft materials so deposited, and ofttimes again by the agency of those elastic forces which it generates, to break up and elevate than into hills and mountain chains. It is also pretty clear that whilst some rocks are thus deposited in horizontal layers by the action of water, others by the action of fire are poured forth in a molten or semi-fluid state from the bowels of the earth and over its surface, or having been once molten but cooled down into a solid state beneath the earth, have afterwards been forced upwards through it. Thus it has become convenient to divide rocks into two classes under the names sedimentary or aqueous (that is formed by water), and plutonic or igneous (that is formed by fire) ; it has also been observed that many of the sedimentary rocks have, by the continued action of heat and under great pressure, been altered entirely in their character and condition; to these the name metamorphic is applied.
It has also been determined that the different sedimentary rocks composing the surface of the earth have not been thrown together carelessly and without method, but there is a certain order so fixed and determined, that if in one part of the earth we find a particular rock B lying above another A, then in every other part we may expect to meet with the same arrangement, so that if we found A at the surface it would be useless to dig downwards with the idea that we should meet with B under it. And it has been further observed, that whilst the rock A contains in it the relies of a certain species of animals in great abundance, the rock B contains few or perhaps none of them, but has instead the remains of another species of animal which is wanting in A. Sometimes the difference between the remains of animals found in two contiguous rocks, A and B, is so great as to fix the idea upon our minds that all the animals which were living whilst A was being deposited having become extinct, or the last race of them having been destroyed by sonic sudden catastrophe, those found in B were entirely a new creation, called into existence by the Almighty Lord of life as more adapted to an altered condition of our globe. The study of these different remains (called fossils) belongs to the science called Palaeontology, and a classification of the different rocks composing the earth's crust has been proposed in accordance with certain results obtained by that study.
Thus the oldest series of sedimentary deposits have been grouped together as belonging to the palæozoic period 6. A newer series, containing as it would seem a new creation of animals, it has been proposed to name as belonging to the mesozoic period 7.; and a still more recent class of deposits with another set of organized beings as of the kainozoic period 8.. The last of these is more generally spoken of under the term tertiary or supercretaceous; the last but one corresponds very nearly with the rocks generally classed under the older name secondary; and the third includes the remaining portion, which was formerly known under the terms primary and transition.
The physical history of the Isle of Man, as read from the characters graven on its surface, is after all but a book with its middle portion torn out and its preface a good deal injured 9.
The Palæozoic period, including the Silurian, Devonian and Carboniferous aeras, the dynasties respectively of Trilobites, Cephalaspides and Megalichthys 10, is fairly enough set before us, as respects bulk at least, and there are many deeply interesting chapters in it; but the Silurian portion has been so much knocked about and scorched by being placed in contact with a heated surface, that we have a difficulty in making out the division of the chapters, and can scarcely tell whether we have Upper Silurian only, or Lower Silurian only, or Upper and Lower Silurian together.
There is however no difficulty in distinguishing the Silurian from the Devonian or Old Red Sandstone aera. A great revolution ushered in those ages when the families of Cephalaspis, Pterichthys, Coccosteus and the Holoptychii held the supreme power. The older dynasty was completely upset and broken in pieces, and its hardier members, after being rudely driven. hither and thither and exposed to continued violence, were at length left to shift for themselves and to take their places as they best could in the new order of things,
Not such was the fate of their successors: though the earlier years of their empire seem indeed to have been years of turbulence and confusion, and there is no doubt of their having been a warrior race, yet the close of it, as far as can be gathered from Manx physical history, was of a peaceful character ; and when a new constitution was called for, the sovereignty passed into the family of Megalichthys, either in consequence of failure in the reigning line, or because the altered character of its dominions was unfitted for the display of its peculiar endowments. And thus the Carboniferous aera began. For a lengthened period affairs were conducted with the greatest order and precision. The public records, as they are handed down to us, appear to have been very accurately made and carefully preserved, and we can trace out the events almost of every year in the exact order of their occurrence; and we have a good deal of information upon the peculiar habits and occupations of the different grades of society in a very densely peopled country. It is true that at first there was a little difficulty in arranging the elements of the new constitution, and affairs wore a dark and gloomy aspect. But after a time all settled down quietly, the coarser materials found their proper level, and peace, social order and industry everywhere prevailed.
At length, from some cause or other, evidently deeplyseated but never satisfactorily made out, a violent émeute took place; the entire fabric of society was broken up, and a succession of disturbances so convulsed this portion of the empire, that amidst the confusion caused by the conflicting masses, it is with the utmost difficulty we can trace out the order of succession. And here the great gap in our history occurs, and most unfortunate is it for the present prosperity of the island that it is so. A few stray leaves 11 indicate that just at that time a deposit was being commenced here with an eye to generations yet unborn, which in other portions of the British dominions forms the true capital which has set agoing the manufactures supplying the world; the capital which has made Manchester and Leeds and Birmingham, and the other rapidly-increasing towns of the districts of coal.
We have here no record whatever of the termination of the Palmozoic period, and the whole too of the secondary series is wanting, as well as a large portion of the tertiary. We enter upon the history again merely where it just begins to end, and it is here also as much confused as where it was so suddenly broken off near the close of the Palmozoie period. But it is soon evident what vast changes have taken place in the physical character of the country and its inhabitants in the interval. It was then a land of warmth and sunshine and teeming with the vegetation of the tropics, we come upon it again as a land cold, dreary and desolate, a treeless and barren waste. But another chapter opens, and it speaks of this region as one of lakes and plains; of plains stretching out and uniting it with England, Ireland and Scotland, over which ranged and reigned the mighty Megaceros 12 . And then is ushered in another period, still a period of change, a period of sinkings and risings again, a period when noble forests of oak, elm and pine, clothed the mountain sides and adorned the valleys ant plains, and Mona again became an island. And last of all conies our own æra, in which the woods have disappeared, the lakes one after another have been drained 13, and smiling corn-fields occupy in them' stead, and the reign of the beasts of the field and fishes of the sea has given way to that of him who was created and made to have dominion over all.
1 See Appendix, note A, and prefatory remarks.
2 Chaloner's History of the Isle of Man, 1656, folio, p. 9.
3 See the Plate, " Distant sea-view of the island as approached from the south-east."
4 See the Plate, " View of the mountain range of the Isle of Man from Kirk Andreas."
5 The term rock however is applied geologically to all the materials of the earth's crust, hard or soft.
6 Old-life period.
7 Middle-life period.
8 Newer-life period.
9 In explanation of this statement and the geological phenomena alluded to in the remainder of this chapter, the reader may refer to the concluding chapter of this work, which contains a summary of the geology of the island.
10 See "The Old Red Sandstone," by Hugh Miller.
11 The fossil plants in the Posidonian shale of Poolvash.
12 Generally known under the term Irish Elk; it ought to have been called Manx Elk, or Megaceros Monensis, as the first described specimen was found in the Isle of Man, and the remains are abundant for the size of the island.
13 See Plate IV., Map of the Isle of Man in 1595, performed by Thomas Durham, as given in Camden's 'Britannia' and in Speed's 'Chronicles,'
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