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time the narrative of the historian was almost exclusively confined to the number of human beings who perished, the number of cities laid in ruins, the value of property destroyed, or certain atmospheric appearances which dazzled or terrified the observers. The creation of a new lake, the engulfing of a city, or the raising of a new island, are sometimes, it is true, adverted to, as being too obvious, or of too much geographical interest, to be passed over in silence. But no researches were made expressly with a view of ascertaining the amount of depression or elevation of the ground, or any particular alterations in the relative position of sea and land; and very little distinction was made between the raising of soil by volcanic ejections, and the upheaving of it by forces acting from below. The same remark applies to a very large proportion of modern accounts; and how much reason we have to regret this deficiency of information appears from this, that in every instance where a spirit of scientific inquiry has animated the eye-witnesses of these events, facts calculated to throw light on former modifications of the earth's structure are recorded. Phenomena attending earthquakes.—As I shall confine myself almost entirely, in the following notice of earthquakes, to the changes brought about by them in the configuration of the earth's crust, I may mention, generally, some accompaniments of these terrible events which are almost uniformly commemorated in history, that it may be unnecessary to advert to them again. Irregularities in the seasons preceding or following the shocks; sudden gusts of wind, interrupted by dead calms; violent rains at unusual seasons, or in countries where such phenomena are almost unknown; a reddening of the sun's disk, and a haziness in the air, often continued for months; an evolution of electric matter, or of inflammable gas from the soil, with sulphureous and mephitic vapours; noises underground, like the running of carriages, or the discharge of artillery, or distant thunder; animals uttering cries of distress, and evincing extraordinary alarm, being more sensitive than men of the slightest movement; a sensation like sea-sickness, and a dizziness in the head, experienced by men: these, and other phenomena, which are still more remotely connected with our present subject as geologists, have recurred again and again at distant ages, and in all parts of the globe. I shall now begin the enumeration of earthquakes with the latest authentic narratives, and so carry back the survey retrospectively, that I may bring before the reader, in the first place, the minute and circumstantial details of modern times, and thus enable him, by observing the extraordinary amount of change within the last 150 years, to perceive how great must be the deficiency in the meagre annals of earlier eras.



Chili, 1835.—The latest earthquake by which the position of solid land is known to have been permanently altered, is that which occurred in South America, on the 20th of February, 1835. It was felt at all places between Copiapo and Chiloe, from north to south, and from Mendoza to Juan Fernandez, from east to west. “Wessels,” says Mr. Caldcleugh, “navigating the Pacific, within 100 miles of the coast, experienced the shock with considerable force.”f Conception, Talcahuano, Chillan, and other towns were thrown down. From the account of Captain Fitz Roy, R. N., who was then employed in surveying the coast, we learn that after the shock the sea retired in the bay of Conception, and the vessels grounded, even those which had been lying in seven fathoms water; all the shoals were visible, and soon afterwards a wave rushed in and then retreated, and was followed by two other waves. The vertical height of these waves does not appear to have been much greater than from sixteen to twenty feet, although they rose to much greater heights when they broke upon a sloping beach.

According to Mr. Caldcleugh, a great number of the volcanos of the Chilian Andes were in a state of unusual activity, both during the shocks and for some time preceding and after the convulsion, and lava was seen to flow from the crater of Osorno. (See Map. Fig. 41, p. 376.) The island of Juan Fernandez, distant 360 miles from Chili, was violently shaken at the same time, and devastated by a great wave. Flames rose there from the sea about a mile from the shore, and illumined the whole island during the night, although it was afterwards ascertained that there was a depth of sixty-nine fathoms water in the spot where the flames had appeared.t

“At Conception,” says Captain FitzRoy, “the earth opened and closed rapidly in numerous places. The direction of the cracks was not uniform, though generally from south-east to north-west. The earth was not quiet for three days after the great shock, and more than three hun

* Since the publication of the first edition of this work, numerous accounts of recent earthquakes have been published; but as they do not illustrate any new principle, I cannot insert them all, as they would enlarge too much the size of my work. Among the most violent may be mentioned those of March, 1829, near Alicant in Murcia—that of Sept. 1827, at Lahore, East Indies—of Jan. 15, 1832, which destroyed Foligno, in Italy,–June 24, 1830, in China, in Tayming, North of Houan—March 9, 1830, in the Caucasus at Kislier—April 1833, Manilla–1833, Isle of Lissa in Adriatic, and Opus. Von Hoff has published, from time to time, in Poggendorf's Annalen, lists of the earthquakes which have happened since 1821 ; and, by consulting these, the reader will perceive that every month is signalized by one or many convulsions in some part of the globe.

# Phil. Trans., 1836, p. 21. At Ibid. p. 25.

Vol. I.-2 X

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dred shocks were counted between the 20th of February and the 4th of March. The loose earth of the valley of the Biobio was everywhere parted from the solid rocks which bound the plain, there being an opening between them from an inch to a foot in width. “For some days after the 20th of February, the sea at Talcahuano,” says Captain Fitz Roy, “did not rise to the usual marks by four or five feet vertically. When walking on the shore, even at high water, beds of dead muscles, numerous chitons, and limpets, and withered sea-weed, still adhering, though lifeless, to the rocks on which they had lived, everywhere met the eye.” But this difference in the relative level of the land and sea gradually diminished, till in the middle of April the water rose again to within two feet of the former high water mark. It might be supposed that these changes of level merely indicated a temporary disturbance in the set of the currents or in the height of the tides at Talcahuano; but on considering what occurred in the neighbouring island of Santa Maria, Captain FitzRoy concluded that the land had been raised four of five feet in February, and that it had returned in April to within two or three feet of its former level. Santa Maria, the island just alluded to, is about seven miles long and two broad, and about twenty-five miles south-west of Conception. (See Map, Fig. 42.) The phenomena observed there are most important. “It appeared,” says Captain Fitz Roy, who visited Santa Maria twice, the first time at the end of March, and afterwards in the beginning of April, “that the southern extremity of the island had been raised eight feet, the middle nine, and the northern end upwards of ten feet. On steep rocks, where vertical measures could be correctly taken, beds of dead muscles were found ten feet above high water mark. One foot lower than the highest bed of muscles, a few limpets and chitons were seen adhering to the rock where they had grown. Two feet lower than the same, dead muscles, chitons, and limpets were abundant.” “An extensive rocky flat lies around the northern parts of Santa Maria. Before the earthquake this flat was covered by the sea, some projecting rocks only showing themselves. Now, the whole flat is exposed, and square acres of it are covered with dead shell-fish, the stench arising from which is abominable. By this elevation of the land the southern port of Santa Maria has been almost destroyed—little shelter remaining there, and very bad landing.” The surrounding sea is also stated to have become shallower in exactly the same proportion as the land had risen; the soundings having diminished a fathom and a-half everywhere around the island. At Tubal, also, to the south-east of Santa Maria, the land was raised six feet, at Mocha two feet, but no elevation could be ascertained at Waldivia, northward of Conception. Ischia, 1828.-On the 2d of February the whole island of Ischia was shaken by an earthquake, and in the October following I sound all the houses in Casamicciol still without their roofs. On the sides of a ravine between that town and Forio, I saw masses of greenish tuff, which had been thrown down. The hot-spring of Rita, which was nearest the centre of the movement, was ascertained by M. Covelli to have increased in temperature, showing, as he observes, that the explosion took place below the reservoirs which heat the thermal waters.” Bogota, 1827.-On the 16th of November, 1827, the plain of Bogota was convulsed by an earthquake, and a great number of towns were thrown down. Torrents of rain swelled the Magdalena, sweeping along vast quantities of mud and other substances, which emitted a sulphureous vapour and destroyed the fish. Popayan, which is distant two hundred geographical miles S. S. W. of Bogota, suffered greatly. Wide crevices appeared in the road of Guanacas, leaving no doubt that the whole of the Cordilleras sustained a powerful shock. Other fissures opened near Costa, in the plains of Bogota, into which the river Tunza immediately began to flow.f It is worthy of remark, that in all such cases the ancient gravel bed of a river is deserted, and a new one formed at a lower level; so that a want of relation in the position of alluvial beds to the existing water-courses may be no test of the high antiquity of such deposits, at least in countries habitually convulsed by earthquakes. Extraordinary

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