GEOLOGICAL CHANGES OF THE EARTH.
There are more things in heaven and earth
Than are dreamt of in our philosophy.—Shakspeare.
The variety of fossil substances, many of them marine productions, which are found in mountains remote from the sea, are undeniable proofs that the earth’s surface has undergone considerable changes, some of which indicate an alteration of climate not easily to be explained. The remains of animals inhabiting hot countries, and the marine productions of hot climates, which are frequently found in high northern latitudes, lead to a suspicion that the earth’s axis was at a very remote period differently inclined from what it is at present. The tropics now extend twenty-three degrees and a half on each side the equator; but if they were extended to forty-five degrees, then the arctic circle and the tropics would coincide, and thence would arise inconceivable variations in the productions and phenomena of the earth. All this would form an amusing speculation to a person possessed of a terrestrial globe, who might tie a thread round it to represent the tropics at forty-five degrees of elevation.
By the gradual operation of the sea and of rivers, the face of the globe has, in the course of ages, undergone very material changes. The former has encroached in particular parts, and retired from others; and the mouths of large rivers, running through low countries, have often been variously modified, by a deposition and transfer of the matter washed down from the land. At Havre, the sea undermines the steep coast; while it recedes at Dunkirk, where the shore is flat. In Holland the Zuyder Zee was probably formed, in the middle ages, by continual irruptions of the sea, where only the small lake Flevo had before existed. The mouths of the Rhine have been considerably altered, as well in their dimensions as in their directions. The mud, as it is deposited by large rivers, generally causes a delta, or a triangular piece of land, to grow out into the sea. Thus the mouth of the Mississippi is said to have advanced above fifty miles since the discovery of America. The island called Sandy Hook, at the entrance of the harbor of New York, was formerly a peninsula attached to the main land. The old citizens of New Haven, Connecticut, point out places where once boats, and even small vessels, used to anchor, but which are now at quite a distance from the water and covered with the dwellings of the inhabitants. Most of the large rivers of the United States are more or less changing their banks, and the places of their channels, from year to year. The sea, within the space of forty years, has retired more than a mile from Rosetta, in Egypt; and the mouths of the Arno, and of the Rhone, consist in a great measure of new land.
The Javanese have a tradition, that in former times the islands of Sumatra, Java, Bali and Sumbawa, were united, and afterward separated into nine different parts. They add, that when three thousand rainy seasons shall have passed away, they will be united. In the Mediterranean, geological phenomena evince, that the island of Malta, and that of Gozo, its dependency, now separated by a wide channel, and the intermediate small island of Cumino, formed, together with the latter, a single island. By the encroachments of the sea, and the subsidence of some parts of the land, the islands of Scilly, the aboriginal inhabitants of which carried on a considerable trade in tin with the Phenicians, Greeks and Romans, are now little more than barren rocks, with small patches of earth interspersed in the hollows. Strabo describes the Phenicians as having been so jealous of their lucrative traffic with these islands, that they ran a vessel purposely on shore, and risked the lives of the crew, rather than have it made known to the Romans. The land within which these tin mines were worked, must now be sunk, and buried beneath the sea. On the shifting of the sands between the islands, walls and ruins are frequently seen; the difference of level, since these walls or fences were made, to prevent the encroachments of the sea, being estimated at sixteen feet. There is little doubt but that there must have been a subsidence of the land, followed by a sudden inundation. This, indeed, seems to be confirmed by tradition, there being a strong persuasion in the western parts of Cornwall, that there formerly existed a large country between the Land’s-end and the islands of Scilly, now laid many fathoms under water. Although there are no positive evidences of such an ancient connection between the main land and these islands, still it is extremely probable, that the cause of the inundation which destroyed the greater part of them, may have reached the Cornish shores, there being several proofs of a subsidence of the land in Mount’s bay. The principal anchoring place, which was called a lake, is now a haven, or open harbor; and the mount, from its Cornish name, signifying the gray rock in a wood, must have formerly stood in a wood, but is now at full tide half a mile in the sea.
Examples of a similar kind, relative to every known country, might be multiplied. One of the most considerable inundations to be met with in history, is that which happened in the reign of Henry I. and which overflowed the estates of Earl Goodwin, forming the banks called the Goodwin or Godwin sands. In the year 1546, a similar irruption of the sea destroyed a hundred thousand persons in the territory of Dort, in the United Provinces, and a still greater number round Dollart. In Friezland and Zealand more than three hundred villages were overwhelmed; and their remains are still visible, on a clear day, at the bottom of the water. The Baltic sea has, by slow degrees, covered a large part of Pomerania; and, among others, overwhelmed the famous port of Vineta. The Norwegian sea has formed several little islands from the main land, and still daily advances on the continent. The German sea has advanced on the shores of Holland, near Catt, to such a degree, that the ruins of an ancient citadel of the Romans, formerly built on that coast, are now under water. The country surrounding the isle of Ely was, in the time of Bede, about a thousand years ago, one of the most delightful and highly cultivated spots in Great Britain: it was overwhelmed, and remained for several centuries under the water, until at length, the sea, by a caprice similar to the one which had prompted its invasions, abandoned the earth, but without the latter being able to recover its primitive state, that of one of the most fertile valleys in the world.
On the other hand, the sea has in many instances, deserted the land; and by the deposition of its sediment in some places, and the accumulation of its sands in others, has also formed new lands. In this manner the isle of Oxney, near Romney marsh, was produced. In France, the town of Aigues Mortes, which was a seaport in the time of Louis IX., is now removed more than four miles from the sea. Psalmodi, also in that kingdom, was an island in the year 815, and is now upward of six miles within the land. In Italy, a considerable portion of land has been gained at the mouth of the river Arno; and Ravenna, which once stood by the sea-side, is now between four and five miles from it. Every part of Holland seems to be a conquest from the sea, and to have been rescued, in a manner, from its bosom. The industry of man, however, in the formation of dikes, is here to be brought into account; for the surface of the earth, in that country, is for the greater part below the surface of the sea.
Three-fifths of the surface of the globe are covered by the sea, the average depth of which has been estimated at from five to ten miles. Demonstrative proofs exist in Great Britain, and in various parts of the world, that great changes have taken place in the relative positions of the present continents with the ocean, which, in former ages, rolled its waves over the summits of our present elevated mountains. To illustrate this subject, and before these proofs are entered on, in the consideration of the geological phenomena named extraneous fossils, it will be proper to introduce the pleasing and truly philosophical view of the successive changes the earth has undergone, contained in Sir Richard Phillips’s Morning Walk to Kew. In passing near the banks of the Thames, Sir Richard was led, in two several places, to introduce the following observations and reflections on this highly curious and interesting subject. They apply the principles and facts of geology in a way in which they may be applied to any river, and indicate how much we are daily surrounded by the wonders of creation, the process of which, as Sir Richard observes, is never ceasing. In passing over the alluvial flat of Barnes common, he introduces the following thoughts, which are given in very nearly his own language.
“On this common, nature still appears to be in a primeval and unfinished state. The entire flat from the high ground to the Thames, is evidently a mere fresh-water formation, of comparatively modern date, created out of the rocky ruins which the rains, in a series of ages, have washed from the high grounds, and further augmented by the decay of local vegetation. The adjacent high lands, being elevated above the action of the fresh water, were no doubt marine formations, created by the flowing of the sea during the long period when the earth was last in its perihelion during our summer months; which was probably thousands of years since. The flat, or freshwater formation, on which I was walking, still only approaches its completion; and the desiccated soil has not yet fully defined the boundaries of the river. At spring-tides, particularly when the line of the moon’s apsides coincides with the syzygies, or when the ascending node is in the vernal equinox, or after heavy rains, the river still overflows its banks, and indicates its originally extended site under ordinary circumstances.
“The state of transition also appears in marshes, bogs and ponds, which, but for the interference of man, would, many ages ago, have been filled up with decayed forests and the remains of undisturbed vegetation. Rivers thus become agents of the never-ceasing creation, and a means of giving greater equality to the face of the land. The sea as it retired, either abruptly from some situations, or gradually from others, left dry land, consisting of downs and swelling hills, disposed in all the variety which would be consequential on a succession of floods and ebbs during several thousand years. These downs, acted upon by rain, were mechanically, or in solution, carried off by the water to the lowest levels, the elevations being thereby depressed, and the valleys proportionally raised. The low lands became, of course, the channels through which the rains returned to the sea, and the successive deposits on their sides, hardened by the wind and sun, have in five or six thousand years, created such tracts of alluvial soil, as those which now present themselves in contiguity with most rivers. The soil, thus assembled and compounded, is similar in its nature to the rocks and hills whence it was washed; but, having been so pulverized, and so divided by solution, it forms the finest medium for the secretion of all vegetable principles, and hence the banks of the rivers are the favorite residences of man. Should the channel constantly narrow itself more and more, till it becomes choked in its course, or at its outlet, then, for a time, lakes would be formed, which, in like manner, would narrow themselves and disappear. New channels would then be formed, or the rain would so diffuse itself over the surface, that the fall and the evaporation would balance each other.
“Such are the unceasing works of creation, constantly taking place on the exterior surface of the earth; where, though less evident to the senses and experience of man, matter apparently inert is in as progressive a state of change, from the operation of unceasing and immutable causes, as in the visible generations of the animal and vegetable kingdoms. Thus water, wind and heat, the energies of which never cease to be exerted, are constantly producing new combinations, changes and creations; which, if they accord with the harmony of the whole, are fit and ‘good;’ but, if discordant, are speedily re-organized or extinguished by contrary and opposing powers. In a word, whatever is, is fit; and whatever is not fit, is not, or soon ceases to be! Such seems to be the governing principle of Nature, the key of all her mysteries, the primary law of creation! All things are the proximate effects of a balance of immutable powers; those powers are results of a primordial cause; while that cause is inscrutable and incomprehensible to creatures possessing but a relative being, who live only in time and space, and who feel and act merely by the impulse of limited senses and powers.”
And, again, the same writer introduces the following apposite remarks on this very interesting subject.
“As I approached a sequestered mansion-house, and the other buildings connected with it, I crossed a corner of the meadow toward an angle formed by a rude inlet of the Thames, which was running smoothly toward the sea, at the rate of four miles an hour. The tide unites here with the ordinary current, and running a few miles above this place, exhibits twice a day the finely reduced edge of that physical balance-wheel, or oscillating fluid-pendulum, which creates the earth’s centrifugal power, and varies the center of its forces. In viewing the beautiful process of nature, presented by a majestic river, we cease to wonder that priestcraft has often succeeded in teaching nations to consider rivers of divine origin, and as proximate living emblems of omnipotence. Ignorance, whose constant error is to look only to the last term of every series of causes, and which charges impiety on all who venture to ascend one term higher, and atheism on all who dare to explore several terms, (though every series implies a first term,) would easily be persuaded by a crafty priesthood to consider a beneficent river as a tangible branch of the Godhead. But we now know that the waters which flow down a river, are but a portion of the rains and snows which, having fallen near its source, are returning to the ocean, there to rise again and re-perform the same circle of vapors, clouds, rains and rivers. What a process of fertilization, and how still more luxuriant would have been this vicinity, if man had not leveled the trees, and carried away the crops of vegetation. What a place of shelter would thus have been afforded to tribes of amphibiæ, whose accumulated remains often surprise geologists, though necessarily consequent on the fall of crops of vegetation on each other, near undisturbed banks of rivers. Happily, in Britain, our coal-pits, or mineralized forests, have supplied the place of our living woods; or man, regardless of the fitness of all the parts to the perfection of every natural result, might here, as in other long-peopled countries, ignorantly have thwarted the course of nature by cutting down the timber, which, acting on the electricity of the clouds, affects their destiny, and causes them to fall in fertilizing showers. Such has been the fate of all the countries famous in antiquity. Persia, Syria, Arabia, parts of Turkey, and the Barbary coast, have been rendered arid deserts by this inadvertency. The clouds from the Western ocean would long since have passed over England without disturbance from the conducting power of leaves of trees, or blades of grass, if our coal-works had not saved our natural conductors; while the Thames, the agent of so much abundance and of so much wealth, might, in that case, have become a shallow brook, like the once equally famed Jordan, Granicus, or Ilyssus.
“I now descended toward a rude space near the river, which appeared to be in the state in which the occasional overflowings and gradual retrocession of the river had left it. It was one of those wastes which the lord of the manor had not yet enabled some industrious cultivator to disguise; and in large tracts of which Great Britain still exhibits the surface of the earth in the pristine state in which it was left by the secondary causes that have given it form. The Thames, doubtless, in a remote age, covered the entire site; but it is the tendency of rivers to narrow themselves, by promoting prolific vegetable creations on their consequently increasing and encroaching banks, though the various degrees of fall produce every variety of currents, and, consequently, every variety of banks, in their devious course. In due time, the course of the river becomes choked where a flat succeeds a rapid, and the detained waters then form lakes in the interior. These lakes likewise generate encroaching banks, which finally fill up their basins, when new rivers are formed on higher levels. These in their turn, become interrupted, and repetitions of the former circle of causes produce one class of those elevations of land above the level of the sea, which have so much puzzled geologists. The only condition which a surface of dry land requires to increase and raise itself, is the absence of salt water, consequent on which is an accumulation of vegetable and animal remains. The Thames has not latterly been allowed to produce its natural effects, because for two thousand years the banks have been inhabited by man, who unable to appreciate the general laws by which the phenomena of the earth are produced, has sedulously kept open the course of the river, and prevented the formation of interior lakes. The Caspian sea, and all similar inland seas and lakes, were, for the most part, formed from the choking up of rivers which once constituted their outlets. If the course of nature be not interrupted by the misdirected industry of man, the gradual desiccation of all such collections of water will, in due time, produce land of higher levels on their sites. In like manner, the great lakes of North America, if the St. Lawrence be not sedulously kept open, will in the course of ages, be filled up by the gradual encroachment of their banks, and the raising of their bottoms with strata of vegetable and animal remains. New rivers would then flow over these increased elevations, and the ultimate effect would be to raise that part of the continent of North America several hundred feet above its present level. Even the very place on which I stand was, according to Webster, once a vast basin, extending from the Nore to near Reading, but now filled up with vegetable and animal remains; and the illustrious Cuvier has discovered a similar basin round the site of Paris. These once were Caspians, created by the choking and final disappearance of some mighty rivers; they have been filled up by gradual encroachments, and now the Thames and the Seine flow over them; but these, if left to themselves, will, in their turn, generate new lakes or basins, and the successive recurrence of a similar series of causes will continue to produce similar effects, till interrupted by superior causes.
“This situation was so sequestered, and therefore so favorable to contemplation, that I could not avoid indulging myself. What, then, are those superior causes, I exclaimed, which will interrupt this series of natural operations to which man is indebted for the enchanting visions of hill and dale, and for the elysium of beauty and plenty in which he finds himself? Alas! facts prove that all things are transitory, and that change of condition is the constant and necessary result of that motion which is the chief instrument of eternal causation, but which, in causing all phenomena, wears out existing organizations while it is generating new ones. In the motions of the earth as a planet, doubtless are to be discovered the superior causes which convert seas into continents, and continents into seas. These sublime changes are occasioned by the progress of the perihelion point of the earth’s orbit through the ecliptic, which passes from extreme northern to extreme southern declination, and vice versa, every ten thousand, four hundred and fifty years; and the maxima of the central forces in the perihelion occasion the waters to accumulate alternately upon either hemisphere. During ten thousand, four hundred and fifty years, the sea is therefore gradually retiring and encroaching in both hemispheres: hence all the varieties of marine appearances and accumulations of marine remains in particular situations; and hence the successions of layers or strata, one upon another, of marine and earthly remains. It is evident, from observation of those strata, that the periodical changes have occurred at least three times; or in other words, it appears that the site on which I now stand has been three times covered by the ocean, and three times has afforded an asylum for vegetables and animals! How sublime, how interesting, how affecting is such a contemplation! How transitory, therefore, must be the local arrangements of man, and how puerile the study of the science miscalled antiquities! How foolish the pride which vaunts itself on splendid buildings and costly mausoleums! How vain the ostentation of large estates, of extensive boundaries, and of great empires! All, all will, in due time, be swept away and defaced by the unsparing ocean; and, if recorded in the frail memorials of human science, will be spoken of like the lost Atlantis, and remembered only as a philosophical dream!”
Such are the speculations of Phillips, containing many things highly interesting and instructive; though, with our advanced knowledge of geology, we involuntarily smile at his “periods” of “ten thousand, four hundred and fifty years,” knowing, as we now do, that some of the great changes of which he speaks must have occupied the long ages of the earth’s chaotic state, before God, by his word, formed it again to life and order and beauty. The merest tyro in science now knows, that in the great facts of geology God as truly speaks by his works, as in the book of revelation he speaks by his word; and though we are far more liable to misunderstand and misinterpret the former than the latter, yet rightly understood there is no discrepancy between the two, but both speak the same language of truth. In the very structure of the earth itself, we have the evidence of the changes it has passed through. The wonderful wrecks of a former state of nature, preserved, like ancient medals or marbles in the ruins of an extinct empire, tell of the progress of the earth in past ages, and teach us that many of the changes which Phillips would refer to comparatively modern times, belong to a period far back of the creation of our first parents, when our planet, though existing, had not as yet been prepared for the habitation of mankind. We will not, however, dwell on these points; but merely allude to them, referring our readers to any of the elementary treatises on geology, where they may find the full details of facts, and also the various theories which reconcile these facts with the statements of the Mosaic history.