although a considerable number of experiments have been made on this difficult subject, there remains much more to be done before satisfactory results can be offered. It is however certain, that great quantities of solid matter are transported by running streams; and with respect to lakes and ponds there can be no doubt, but they are gradually. filling up, and that if the same causes continue which we have described, all these bodies of water will finally be re-placed by dry land.

But there can be no possible estimate made of the time required for such an event, since the quantity of solid matter which streams transport, must be constantly decreasing in proportion as lakes and ponds approach the level of the country in which they are. In a flat country therefore, a lake may remain for centuries without any appreciable elevation of its bottom.

The great depth of some lakes at the present day, when these circumstances are considered, is a good proof of the newness of the present order of things on the earth, and consequently of the truth of the Mosaic history of its creation.

With respect to the level of the sea, it has been shown that no change has taken place in the Baltic, and we may also state at this place, that it will be seen hereafter, that the remains of Roman buildings show that the Mediterranean sea has not changed its level for the last 2000 years. We may therefore conclude, that either the quantity of matter carried into the sea has made no appreciable difference with its general level, or that as much solid matter is thrown on the land at one place as is carried into it in another.

DESTRUCTION OF ROCKS.

The causes now described which have produced changes on the surface of the earth, are chiefly such as transport loose materials from one place to another. But there is another cause of change, which although noticed in the first part of this article, must be more particularly described. This is the destruction of rocks.

"If in contemplating," says Dr. Macculloch, "the towering peaks, and the solid precipices of an alpine region, braving the fury of the elements and the floods of winter,

56

FALL OF MOUNT GRENIER.

the spectator is at first impressed with the character of strength and solidity, which nature here seems to have conferred on her works, it requires but a moment's reflection, to show that every thing around him bears the marks of ruin and decay. Here he learns to withhold his regret at the perishable nature of all human labors,—at the fall of the strong tower, and the solid pyramid, when he sees that the most massive rocks, those mountains which seem calculated for eternal duration, bear alike the marks of vicissitude and the traces of ruin."

"In these great revolutions, however, other agents must co-operate; and the first here to be considered is the power of frost. Expanding as it freezes, the water which has entered the fissures acts with irresistible force, and detaches those enormous masses, which in the seasons of winter and spring, daily fall from the mountains. Greenland, it is said that these effects often take place with a noise emulating thunder; but if less conspicuous, they are sufficiently common in all alpine regions that are subject to the extreme vicissitudes of heat and cold."Geology, Vol. i. p. 248.

In

To this cause in a great measure is to be attributed the ruin of sea cliffs, which on some coasts present such striking and singular appearances. The constant action of the ocean lashing the inferior parts of these cliffs, also produces its effects, and is often the cause of large masses being precipitated into the water. The perpetual rubbing of the smaller stones against the larger, on the borders of the sea, is another cause which in the course of time produces considerable effects; and hence all such stones have lost their angles and become completely smooth and rounded.

Fall of Mount Grenier. The fall of a part of Mount Grenier, one of the calcareous mountains of Savoy, illustrates the effects of frost, and the gradual undermining of rocks by torrents. Mount Grenier is upwards of 4000 feet high, and rises abruptly above the plain on which it stands. The top, or cap, is an immense mass of limestone, 600 feet thick, below which are strata of a softer kind, and it is to the decay of the latter that the fall is attributed, the cap being undermined by the gradual erosion and removal of the under strata. The fall took place in the year 1248. The larger masses, says Mr. Bakewell,

evidently came from the upper, or highest part of the mountain, and the velocity they acquired by the fall must have been at least 300 feet per second, before they reached the ground. As these immense masses struck obliquely against the base of the mountain, they thus acquired a projectile force which spread them far into the plain. These masses were in such quantity, and were projected to such distances, as to cover nine square miles of surface, and to entirely bury five parishes, together with the town and church of St. Andre. In the course of years the rains, or currents of water from dissolving snow, have furrowed channels between the larger masses of stone, and washing away part of the loose earth, have left an immense number of conical hills still remaining. So deep

and vast was the mass of ruins which covered the town of St. Andre, and the other parishes, that except a small bronze statue, no individual article belonging to any of them has been found to this day--Bakewell's Geology.

Fall of Rocks from the Alps. A part of a mountain near Servos, belonging to the Alpine range, and on the road to Chamouny, fell down in the year 1751. This continued several days, mass after mass being precipitated, while an immense volume of dust, the consequence of friction, by the sliding of the rocks on each other, rose so high, and was so dense as to have been seen at the distance of twenty-five miles. A succession of reports, like the firing of heavy cannon, announced the fall of these masses day and night. The aggregate amount thus precipitated was estimated by Donati at 3,000,000 of cubic fathoms, or fifteen millions of cubic feet, a quantity sulicient to form a large hill.

DESTROYING EFFECTS OF THE SEA.

Mr. Lyell has adduced many instances of the power of sea waves to move large masses of solid rock. In the Shetland Isles this effect has been quite surprising. In 1818, during a storm, a mass of granite, nine feet by six, was thrown by the waves up a declivity to the distance of 150 feet; and, in the winter of 1802, a mass of rock

eight feet by seven, and five feet thick, was moved to the distance of ninety feet, by the same force.

The reader who remembers the immense power which velocity gives a sea wave, as above illustrated, will be at no loss to comprehend why the strongest ships are sometimes reduced to fragments in a few minutes; nor will he wonder at the destroying effects which a wide ocean must produce on a coast, which is not guarded by a strong barrier of solid rocks.

Destruction of the Village of Mathers. The village of Mathers, on the east coast of Scotland, was destroyed by an inroad of the sea, in 1795. This town was guarded by a barrier of limestone rock next the shore; but during a storm the waves of the ocean broke through this barrier, and in one night destroyed and swept away the whole village. The sea penetrated 150 yards inland, where it has maintained its ground ever since.

Eastern Coasts of England. The eastern coasts of England are constantly suffering from the inroads of the sea. On the old maps of Yorkshire, many spots are marked as the sites of towns which are now sand banks in the ocean. A greater or less portion of the coasts of Norfolk and Suffolk are every year swallowed up by the sea. The town of Sherringham, on this coast, exhibits a melancholy proof of this fact. With respect to this town, Mr. Lyell states, that at one point there is now a depth of water of 25 feet, (sufficient to float a frigate) where only 48 years ago, there stood a cliff fifty feet high, with houses upon it. Further to the south are cliffs more than 200 feet high; more or less of which are every year precipita ted into the ocean, in consequence of being undermined by the waves. The whole site of the ancient town of Cromer now forms a part of the bed of the German ocean, the inhabitants having gradually pulled down their houses and removed inland as the sea encroached upon them; and, from their present situation, they are in danger of being dislodged by the same cause. From this neighborhood, in the year 1822, a mass of earth and rocks was precipitated into the sea, to the extent of twelve acres, the cliffs being 250 feet high; and on the same coast, three ancient villages, several manors, and large portions of a

number of parishes have, from the same cause, gradually disappeared, and been replaced by the ocean.

Since the time of Edward the Confessor, as appears by the records, the sea-coast town of Dunwich has lost in succession, a monastery at one time; at another, several churches; at another, 400 houses; and, subsequently, another church; the town hall and jail, together with many other buildings, all precipitated into the sea.

These are given as specimens of the devastating effects of the sea in different parts of the world, and, by which, it appears that if on the one hand, large tracts of coast are forming, and encroaching upon the ocean in one part of the world, as in the Baltic, and on the coasts of Italy, so on the other hand, the sea is encroaching on the land in other parts, probably to an equal extent.

In many instances, inundations from the sea, have been the means of effecting, not only great changes in the surface of the earth, in a short period of time, but also of destroying vast numbers of human beings. On the coast of Holland these disasters have been peculiarly destructive, as well as on the coast opposite.

A considerable peninsula which lay between Groningen and East Friesland, and was thickly inhabited, was partly overwhelmed in 1277, and a considerable portion of the land carried away, with many houses and inhabitants. During the fifteenth century, other portions were destroyed by the same cause, and a part of the town of Forum, a place of considerable size, was swept away. In 1507, not only the remainder of Forum was engulphed, in spite of the erection of dams, but also several market towns, villages and monasteries, were entirely destroyed, together with their inhabitants.

Further to the north, anciently lay the district of North Friesland. This was a peninsula; but in 1240, the sea destroyed the land next the coast, and thus formed an island called Northstrand. This island was originally of considerable extent, but the sea, from time to time, swept away small portions of it, until the inhabitants became so concentrated, that when the island was only four geographical miles in circumference, their number was still nine thousand. At last, on the night of the 11th of October, 1634, a flood from the sea swept over the whole island, and destroyed at once a great proportion of the inhabitants, all the houses, churches and cattle, carrying away