At the present moment the land is again subsiding and in the same gentle manner.

What was once deemed an encroachment, or rather a rise in the level of the sea, is now well understood to be but the movement of the coast, gently subsiding, this fact is well illustrated by the movement of land in Sweden, which is now, and has been for ages in course of elevation in some places, and depression in others, rising in the northern, and sinking in the southern parts. The proof of this great change, which had long been suspected, was complete upon examining the marks cut upon the rocks by the officers of the pilotage establishment of Sweden. It was found that in the space of fourteen years, the rise had been from four to five inches. The prevalence of marine shells, at some distance in the interior, of the same species as those now living in the neighboring seas, renders in highly probable that this rise has been going on for a long time, in certain portions of that country. The rocks of the coasts of Norway and Sweden, are pricipally gneiss, mica-schist, and quartz, and will retain their particular configuration or appearance unaltered for a long series of years, there seems therefore, but little room for any doubt as to the change of level of the land and sea, determined by the ancient landmarks, the appearance of new shoals, the elevation of the lines cut to mark the height of the water years previous, and the abundant occurrence of marine shells attached to the rocks at the distance of even fifty miles from the sea coast. From some phenomena occurring near Stockholm, it would seem that the land has been depressed and then re-elevated. In the year 1819, in digging a canal at Sodertelje, a place sixteen miles south of Stockholm, for the purpose of uniting Lake Maeler with the Baltic, at a depth of sixty feet, the workmen came upon what appeared to have been a buried fishing-hut, constructed of wood, it was in a state of decomposition, and crumbled away on exposure to the air. On the floor of the hut, which was in better preservation, was a fire-place composed of a ring of stones, within which were found cinders and charred wood, and outside were boughs of fir, still retaining the leaves and bearing the marks of the axe. Besides the hut, several vessels of an antique form were found,

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The

having their timbers fastened together with wooden pegs, instead of nails, indicating their great antiquity. The situation of the hut seems only to be accounted for on the supposition of a change similar to that on the shores of the Bay of Baiæ, first subsiding to a depth of more than 60 feet, and subsequently being re-elevated. Examples of this gradual elevation are by no means rare. coast of Newfoundland, in the neighborhood of Conception Bay, and probably the whole island is rising out of the ocean, at a rate which promises at no very distant period, materially to affect, if not render useless, many of the best harbors on its coast, At Port-de-Grave, a series of observations have been made, which undeniably prove the rapid displacement of the sea-level in the vicinity. Several large flat rocks, over which schooners might pass some thirty or forty years ago with the greatest facility, are now approaching the surface of the water, so that it is scarcely navigable for a skiff. Dr. Jackson describes a deposit of recent shells in clay and mud, with the remains of balani or barnacles, attached to trap rock twenty-six feet above the present high-water mark, on the margin of Lubec Bay in the State of Maine.

Changes like these which we have just described, have been of universal occurrence. Upon this subject Cuvier remarks, "The lowest and most level lands, when penetrated to a great depth, exhibit nothing but horizontal strata, consisting of various substances, almost all of them containing innumerable productions of the sea; similar strata, similar productions, compose the hills, even to a great height. Sometimes the shells are so numerous that they form, of themselves, the entire mass of the stratum. They are everywhere so completely preserved. that even the smallest of them retain their most delicate parts, their slenderest processes, and their finest points. They are found in elevations above the level of the ocean, and in places to which the sea could not now be conveyed by any existing causes. They are not only enveloped in loose sands, but are incrusted by the hardest stones, which they penetrate in all directions." Every part of the world, the continents, as well as all the islands of any considerable extent, exhibits the same phenomena; these animals have, therefore, lived in the sea, and the sea consequently must

have existed in the places where it has left them. Indeed,t ne proofs of elevation and subsidence, are everywhere too palpable to be mistaken. Stratified rocks, or rocks deposited by the agency of water, form the summits of the highest mountains, elevated many thousands of feet above the level of the sea. In these strata, the remains of shells, fishes, and other marine animals are imbedded. When in addition to this, we observe these strata not horizontal, but nearly vertical, we cannot resist the conclusion that they have either been violently upheaved by some tremendous convulsion, or gradually raised by the irresistable agency of a long continued subterranean force. The evidence of disturbance of the strata, afforded by certain marine worms is important, and is an instance of the subservience of the actions of even the meanest of created beings, to the elucidation of truth. It is well known that certain of these worms, inhabiting straight and tubular shells, bore the sand in a vertical direction, as represented in this figure, and if the strata remained undisturbed the

But the shells

direction of the bore would be always vertical. are found in various strata, making various angles with the horizon according to the elevation of the strata, as shown in the figure below, and occasionally, a more recent shell will have the

α

vertical direction as at a, boring the cavity subsequently to the elevation of the strata. Beds of pebbles, once deposited in regular horizontal strata, are found making angles with the horizon, thus witnessing the same fact.

We will now briefly consider some of the most remarkable earthquakes which have occurred within the historic period. We commence with the well known one which nearly destroyed the

EARTHQUAKE IN CALABRIA, 1783.

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city of Messina in 1783. The shocks commenced on the 6th of February, and ended March 28th, though repeated at intervals for a space of four years. The full and interesting accounts of this convulsion, carefully prepared by scientific men, render this earthquake of much more importance to the geologist than many others which have occasioned infinitely more destruction of life and property, but of whose effect in changing the country we are almost entirely ignorant. The concussion of this earthquake was felt over a great part of Sicily, and the whole of Calabria, extending as far as Naples. The centre of the surface which suffered the most, was the small town of Oppido, in the neighborhood of Atramonte, a high, snow-capped peak of the Appenines. From this point, for a distance of twenty-five miles in all directions, nearly all the towns and villages were destroyed, and if we describe a circle with the same centre, having a radius of seventytwo miles, it will include all the country affected by this earthquake. The first shock, February 5th, threw down in the course of two minutes, the greatest part of, the houses in all the cities, towns, and villages, from the western acclivities of the Appenines, (which traverse Calabria from north to south) in upper Calabria, to Messina in Sicily, convulsing the whole country. The granitic chain of mountains was slightly affected by the first shock, but more sensibly by those that followed; the principal shock being propagated with a wave like motion through the tertiary sands, sandstones, and clays, from west to east; and where the line of tertiary rocks joined the granite, the shocks were most severe, probably owing to the interruption of the undulatory movements of the softer strata by the harder granite, which prevented the passage of the shocks to the countries on the opposite sides of the mountain range. About 200 towns and villages were destroyed, more than one hundred hills slid down, fell together and damming up rivers, formed lakes. The quay at Messina sank down fourteen inches below the level of the sea. Deep fissures were caused at several places, and many subsidences, and upraisings of the ground took place, and the general features of the country were so altered that they could scarcely be recognized. Thus in a very short space of time the whole country was as

much changed as though it had been exposed to common influences a thousand years, and over 100,000 persons were destroyed. The movement of the ground was not only horizontal, but vorticose, at some places. This was shown by the partial turning of the stones of two obelisks at the convent of St. Bruno, in the small town called Stefano.del Bosco, as exhibited in the wood cut below. The position of the stones was changed nine inches without their falling.

The most destructive and tremendous earthquake on record, is that which overthrew Lisbon in 1775. The first shock was on the morning of November 1st, about half past nine, when, without any other warning than a noise like thunder, heard underground, the foundations of this ill-fated city were violently shaken, and many of the principal edifices fell to the ground in an instant. Then with scarcely a perceptible pause, the rumbling noise changed into a quick rattling sound, resembling that of a wagon driven violently over the stones, this shock threw down every house, church, convent, and public building; overwhelming the miserable population with the ruins; it continued about six minutes. It is said by those who witnessed the effects of this earthquake, that the bed of the river Tagus appeared dry in many places, and boats sailing on the river were struck violently