a large lake was formed, and much property and many lives destroyed.

The effects of this dreadful calamity may in some measure be imagined when it is known, that although Iceland did not, at that time contain more than fifty thousand inhabitants, there perished nine thousand human beings by this single eruption, making nearly one in five of the whole population. Part of them were destroyed by the burning lava itself, some by drowning, others by noxious vapors which the lava emitted, and others in consequence of the famine, caused by the showers of ashes which covered a great proportion of the island, and destroyed the vegetation. The fish also, on which the inhabitants depended, in a great measure, for food, entirely deserted the

coast.

The quantity of lava which Skaptar Jokul emitted during this eruption, was greater than is recorded of any other volcano. The two principal branches or streams of lava, flowed chiefly in different directions. The length of the smallest was forty miles, and of the other fifty miles. The breadth of that branch which filled the Skapta, was from twelve to fifteen miles, and the other about seven miles. The ordinary depth of each was about 100 feet, but in narrow defiles it was more than 600 feet deep, and in many places from 200 to 300.

Allowing that the united breadth of this vast lava stream was 20 miles, and the whole length 90 miles, then this mountain, at a single eruption, threw out a quantity of lava which covered a surface of 1800 square miles, an area equal to the fourth part of the State of Connecticut, and nearly one half the size of Rhode Island.

When it is considered that the depth of the whole might average 150 feet, we may go into calculations concerning the quantity of matter thrown out, but we can have no conception of the force required to elevate such a stream of melted rock through the crust of the earth.

Eruption of Jorullo, in 1759. Jorullo is situated in the interior of Mexico, about 100 miles from the nearest sea. This mountain, as already stated, affords the only known instance of a volcano, at a distance from some ocean. also affords an instance of the production of a new volcanic mountain, within the memory of man.

It

In June, 1759, subterranean sounds of an alarming kind were heard by the inhabitants of this district, and these were followed by earthquakes, which succeeded each other for two months. In the month of September, flames were seen to issue from fissures in the ground, and from the same place, red hot rocks were thrown to an immense height. Soon after, six volcanic cones were formed of lava and the fragments of rock, thrown up from the earth, in the same neighborhood. The least of these was three hundred feet in height. In the midst of these cones, rose Jorullo, which was formed in the same manner, and soon rose to the height of 1600 feet by the accumulation of lava and fragments of rock. The small cones ceasing their action, Jorullo became the great outlet of volcanic matter, and continued to emit lava and large fragments of primitive rock, for many months. Jorullo has continued to emit flames ever since its formation.

Volcano of Sumbawa. Sumbawa is one of the Molucca Islands; and the mountain from which occurred, on some accounts, the most extraordinary volcanic eruption of which any accounts have been recorded, is called Tomboro.

This eruption commenced on the 5th of April, 1815, but was most terrific on the 11th and 12th of that month, nor did it cease entirely, until sometime in the following July. The explosions so much resembled the firing of heavy cannon at a distance, that the people of many vessels at sea, supposed there was a great naval engagement within hearing, but could not imagine what nations were engaged.

The commanders of some ships, and of several English forts, gave orders to prepare for battle, though they were several hundred miles distant from the mountain. At Sumatra, these tremendous explosions were distinctly heard, though not nearer than 900 miles from Tomboro. They were also heard at Ternate, in the opposite direction from Sumatra, at the distance of 720 miles from the mountain.

So immense in quantity was the fall of ashes, that at Bima, forty miles from the mountain, the roof of the English Resident's house was crushed by the weight, and many other houses in the same town were rendered uninhabitable from the same cause. At Java, 300 miles distant, the air was so full of ashes, that from this cause at mid-day, it is said the darkness was so profound, that nothing like it

had ever before been experienced, during the most stormy night.

Along the coast of Sumbawa, the sea was covered with floating lava, intermixed with trees and timber, so that it was difficult for vessels to sail through the mass. Some captains, though at a long distance at sea, mistook this mass for land, and sent out their boats in order to ascertain ́the safety of their situations. The sea, on this and the neighboring coasts, rose suddenly to the height of twelve feet, in the form of immense waves, and as they retired, swept away trees, timber, and houses, with their inhabitants. All the vessels lying near the shore were torn from their anchorings, and cast upon the land. Violent whirlwinds carried into the air men, horses, cattle, trees, and whatever else was in the vicinity of the mountain. Large trees were torn up by the roots, and carried into the sea. But the most calamitous part of the account still remains; for such were the tremendous effects of the burning lava; the overflowing of the sea; the fall of houses; and the violence of the whirlwind, that out of 12,000 inhabitants on this island, only twenty-six individuals escaped with their lives, all the rest being destroyed in one way or another.

The whole island was completely covered with ashes, or other volcanic matter. In some places, the bottom of the sea was so elevated, as to make shoals, where there was deep water before; and in others, the land sunk down, and was overflown by the sea.

The details of this awful calamity were collected, and published by Sir Stamford Raffles, then Governor of Java, who required all the residents in the various districts under his authority, to send him a statement of the circumstances which fell under their several observations.-See Raffles' Hist. of Java; and Brande's Quart. Jour. vol. i.

EARTHQUAKES.

Having thus given a short history of a sufficient num ber of volcanic eruptions, to acquaint the geological student with the phenomena, and of the tremendous as well as calamitous effects of these mighty agents, we will next refer to the subject of earthquakes, as resulting from the

same cause.

Earthquake of Calabria. "Of the numerous earthquakes," says Mr. Lyell, “which have occurred in different parts of the globe, during the last 100 years, that of Calabria, in 1783, is the only one of which the geologist can be said to have such a circumstantial account, as to enable him fully to appreciate the changes which this cause is capable of producing in the lapse of ages. The shocks be gan in February, 1783, and lasted nearly four years, to the end of 1786." The importance of the earthquake in question, arises from the circumstance, that Calabria is the only spot hitherto visited, both during and after the convulsions, by men possessing sufficient leisure, zeal, and scientific information, to enable them to collect and describe with accuracy, the physical facts which throw light on geological questions-Lyell, vol. i. p. 412.

Authors who witnessed the phenomena of these convulsions, are quite numerous. Among them, it is said that Pignataro, a physician, who resided at the centre of the earthquakes, and who kept a register of the number and force of the shocks, is among the most correct.

The

Royal Academy of Naples, also sent a commission from their own body to Calabria, accompanied by artists, with instructions to describe and illustrate by drawings, the ef fects of these terrible convulsions; and Sir William Hamilton, who surveyed this district before the shocks had ceased, has added many facts not recorded by others. Our limits will, however, allow only a very brief summary of the facts, from these several sources.

The subterranean concussions were felt beyond the confines of Sicily; but if the city of Oppido, in Calabria, be taken as the centre, a circle around it, whose radius is twenty-two miles, would include the space which suffered the greatest calamities. Within this circle, all the towns and villages were almost entirely destroyed.

The first shock, which took place on the 5th of February, 1783, threw down, in the space of two minutes, a greater part of the houses, within the whole space above described. The convulsive motion of the earth, is said to have resembled the rolling of the sea, and that in many instances, it produced swimming of the head, like sea-sickness. This rolling of the surface, like the billows of the sea, was like that which would have been produced by the agitation of a vast mass of liquid matter under the ground.

In some walls which were shattered, the separate stones

were parted from the mortar so as to leave an exact mould where they had rested, as though the stone had been care. fully raised from its bed in a perpendicular direction; but in other instances, the mortar was ground to powder between the stones, as though they had been made to revolve on each other.

It was found that the swelling, or wave-like motions, and those which were called vorticose, or whirling, often produced the most singular and unaccountable effects. Thus, in some streets, in the town of Monteleone, every house was thrown down, except one, and in some other streets, all except two or three; and these were left uninjured, though differing in no respects from the others.

In many cities all the most solid edifices were prostrated, while those which were slightly built, escaped; but, in others, it was precisely the reverse, the massive buildings being the only ones that remained standing. Fig. 6.

But, perhaps, the most singular effect was that produced on a pair of obelisks, at the convent of St. Bruno, where the different stones composing these monuments, were moved on each other, in a manner altogether unaccountable, unless, indeed, it can be supposed that .he earth, where each stood, underwent a rapid gyratory motion. The shock which shook the convent, is said to have been of that kind which writers describe by the term vorticose, or whirling. The annexed cut, fig. 6, will convey an idea of these effects.