covering a dish of quicksilver with sand or soil, and then giving the vessel a slight agitation.

The connection between volcanoes and earthquakes has been so generally observed, that no one at the present day denies that their causes must be the same. Earthquakes precede volcanoes, and when a wave of the lava reaches an aperture, there happens an eruption, and the earthquakes are diminished in force, or cease entirely, because the internal pressure is thus relieved.

In proof of this connection, the elevation of all new islands, and the formation of all new volcanoes, and most commonly the eruptions of old ones are preceded by, or accompanied with earthquakes, especially where the latter have sometime lain dormant. The elevation of Sabrina, of the Aleutian Island, of Monte Nuovo, and the formation of Jorullo, together with what is generally known of Vesuvius and Etna, are examples.

It is true that, in some instances, earthquakes happen, both at great distances from volcanoes, and in their vicinities without any eruption. But, when this is the case, the most calamitous consequences are produced, because the confined matter which causes the earthquakes cannot escape. This was the case, as already noticed, with respect to the earthquakes of Calabria, which destroyed 60,000 people, there being no eruption either of Etna or Vesuvius. It is probable that this was prevented, by the masses of cooled lava, by which these apertures were clogged. The great earthquake of Lisbon was also unattended by volcanic eruptions.

When the shocks commenced which ended in the elevation of Monte Nuovo, it was expected, of course, that an eruption of Vesuvius would ensue, but instead of this, after the earthquake had continued with great force for twenty-four hours, the earth opened with a tremendous noise, and, throwing out blocks of lava, pumice and ashes, formed that mountain in 1538. Vesuvius, with a single slight exception, had remained dormant from 1306, and shewed no signs of commotion during the elevation of Monte Nuovo. Now, had there been less resistance at the crater of Vesuvius, than there was on the plain, there would have been an eruption; and no new mountain would have been formed. But Vesuvius continued torpid until 1631, during which period Etna was peculiarly active, suffering frequent and terrible eruptions. This cir

cumstance affords a strong argument in favor of a subterranean communication between these two mountains, Etna occasionally serving as an outlet for the elastic fluids, and lava, a part of which would otherwise be emitted at Vesuvius, and, perhaps, the latter in its turn, answering the same purpose during the torpid state of the former.

Again, the earthquake of Lisbon, as already stated, was felt in all parts of Europe, and also in Africa, and South America, as well as by ships sailing in the intermediate seas. Now it cannot be reasonably supposed, that a subterranean convulsion could be communicated by the mere vibration of the earth, to the distance of so many thousand miles, and especially from one side of the Atlantic to the other, under the ocean. If there existed no other evidence than this, of an interior fluctuating medium below the crust of the earth, it would be more philosophical, as well as reasonable, to infer that such an one did exist, than to believe that the earth was capable of transmitting a vibratory motion, however strong, to the distance of one fourth of its circumference.

Finally, another proof of the existence of an immense mass of igneous matter under the surface of the earth, is the quantity of lava emitted by some volcanoes. Many instances might be adduced, but we will here only refer to that of Skaptar Jokul, in 1783, an account of which has been given. There the quantity of lava covered a surface equal to ninety miles long, and twenty broad, making an area equal to 1800 square miles. The depth or thickness was generally about 100 feet, but, in some places, to a considerable extent, 600 feet deep. Perhaps, therefore, it would not be an over estimate to call the average depth 150 feet. This quantity, if consolidated, would by calculation have formed a massive globe, of about six miles in diameter.

Now if the matter of this eruption came from the immediate vicinity of the mountain, it is plain that the strata under it for six miles in extent must have been thrown upon the surface, and a cavity produced of a proportionate size; but this is highly improbable, if not absolutely impossible, from the very nature of the case, because if we suppose a cavity, or definite space whence the lava proceeded, we must also suppose it constantly full of igneous matter, at least in the neighborhood of the aperture, otherwise it would not have flowed from the crater. For,

we cannot believe that in a cavity of such dimensions, steam, or any other elastic body could have operated in such a manner as to throw out all, or the greatest part of its contents.

From all we have adduced on this subject, we cannot but conclude, that the phenomena of earthquakes and volcanoes, indicate the existence of an ocean of melted lava, constantly existing at an unknown depth under the surface of the earth, and that these phenomena may, in most of their varieties, be accounted for by such a hypothesis, and by no other which has yet been proposed. It is, therefore, reasonable to infer that such a mass of igneous matter does actually exist.

ELEVATION OF CONTINENTS FROM THE SEA.

The occurrence of sea shells, and the remains of marine animals, at a distance from any existing ocean, is a fact of common observation. Some of these remains are deeply buried in solid strata, while others are found in alluvia near the surface. We have noticed in the preliminary part of this work, that such remains excited the attention of the earliest geological observers, and that for want of a more philosophical mode of accounting for these phenomena, they were then considered, not real shells, but the products of plastic nature.

A great proportion of Italy is covered by an alluvial soil, containing sea shells, and occasionally the remains of quadrupeds, both of living and extinct species, such as the elephant, hippopotamus, rhinoceros, mastodon, &c. In this country, in the states of New-York, of Ohio, and indeed throughout the great valley of the Mississippi, fossil shells are found; and, as in Italy, there occurs alsó the remains of ancient quadrupeds.

The theory, long since suggested, that the great lakes of North America, are the deeper beds of an inland sea, which once covered a great extent of land, a part of which is now dry, has undoubtedly many circumstances in its favor, and indeed may be considered as a well founded geological fact. In this instance, if, as some geologists suppose, this ancient sea has been drained by the bursting of some barrier, it is a circumstance which will account for

the appearance of shells not situated higher than the bed of the former sea. But it is believed that in many places, marine organic remains are found, much more elevated than any reasonable hypothesis could have placed the bed of the former sea. The situations of these cannot, therefore, be accounted for on the supposition that they were left by the retiring waters.

In Italy, besides the more common marine remains of shells and small fish, there are found the bones of whales and dolphins, and sometimes entire skeletons of these fish occur at the elevation of 1200 feet above the sea.

The bones of whales, thus found, are in a high state of preservation, and are often encrusted with oyster shells, a good proof that they have not been transported, and that the sea for a long time remained over them, after they had been denuded of their flesh.

But it will be seen by the following extract from Cuvier, that such appearances are much more common than has been supposed.

"The lowest and most level lands," "when says he, 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 almost every where 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 every part 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 encrusted by the hardest stones, which they penetrate in all directions. Every part of the world, both the hemispheres, all continents, all islands of any considerable extent, exhibit the same phenomena. They have, therefore, lived in the sea, and have been deposited by the sea; the sea therefore, must have existed in the places where it has left them."

When we find in many parts of the world, stratified rocks, forming the summits of the highest mountains, ele. vated many thousands of feet above the level of the sea,

and when we suppose that the objects we are contemplating, were once covered by water, we are strongly impressed with the changes which the relative levels of the water and land must have undergone. And when we find the remains of shell fish embedded in these strata, we cannot hesitate to admit that these rocks have once been cov

ered by the ocean. When, lastly, we observe that those

beds, which must once have been horizontal, are now vertical; that they are inclined, broken, bent and dislocated in innumerable ways, we are forcibly led to conclude that their present distance from the sea has been accompanied by violent alterations in the form of the surface; and that it has been produced by the action of enormous powers.— Macculloch, vol. i. p. 86.

Allowing that these strata have once been under the sea, and which, from the circumstances, is proved beyond all doubt or controversy, the question to be examined, is, whether the ocean has retired to a lower level, or whether the land, by some enormous force, has not been elevated above the water.

The phenomena of shells in strata, were once attributed to the Mosaic deluge, but we need not at the present day, employ arguments to show the impossibility of such an origin. 150 days was too short a period to have produced such effects.

It has been ascertained that some of the Peruvian mountains contain sea shells, at an elevation of fourteen thousand feet above the level of the sea; and that the nature of the strata in which they are contained, is such as to show that these mountains must for a long period have been submerged. Hence it is plain that no hypothesis connected with the deluge, can explain this fact.

Now if the sea has retired in a gradual manner, from such a height, within a period of five or six thousand years, its level ought now, at this rate of depression, to be at least four thousand feet lower than it was two thousand years ago; but facts, with respect to the Baltic and the the Mediterranean, tend to prove, that since the Christian era, the ocean has not changed its level, in any appreciable degree.

There is therefore, not the least probability, or even possibility, that marine organic remains situated above the sea, or imbedded in strata at a distance from it, can be accounted for by any supposition connected with the depres sion of the waters of the ocean.