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Show Y NEW CONES TIIROW~ 'UP. 382 THlRT ' fi t nts or of a storm whtch was f h laces by ery orrc ' h h d ing o ot er p 'f . t the inhabitants, as t ey a equally new and ternlyi~g o ntry before. On the 10th of k one in t 1eir cou . never nown i h hill was thrown up, whiCh, on t1 e same January, 1731, a~ g ck a ain into its own crater: fiery day' precipitated Itself bfa 'tg t the sea. On the 3rd of k f 1 a flowed rom I o . M h broo s o av Others were thrown up m arc ' February a new cone arose. Numerous other volcanic and poured forth la~a-;~:.::tin succession, till at last t~eir cones were subsequent yb th' ty In June, 1731, durmg number amoun ted to a . out Ir · · h 11 the banks and shores m t e a renewal of the eru~tlionds, ~ere covered with dying fish, western part of . the lS an of which had never b e1e ore b een of different specles, some f m the sea with loud deto- S k and flame arose ro ' . . seen. mo e df 1 commotions lasted without mter-nations. These drea . u and a great emigration of the ruption for five successtve years, inhabitants became necessary. s Von Buch was assured As to the height of thde nflew ~ohn.e g' St Catalina lay buried 1 tan ouns m · that the former y gr~a 1 . h . d he observes, that the most under hills 400 feet m l.eig t ' .~~00 feet above its base, and elevated cone of the senes ~~~at several others were nearly as 1378 feet above the sea, an ll <Yed in one line, about two Th ents were a arrano d high. e new v d . a direction nearly east an geographical miles long, an b.;~ f Von Buch's conjecture, west. If we admit the proba ; ~y o f an open cleft, it seems that these vents opened alongh.t le ui::e:ranean fissure was only t ppose that t IS s h nt necessary o su ' he surface by degrees, or that t e re prolonged upwards to t. 11 the case with fissures caused was narrow at first, as IS usua 1 y . fl. ids might escape from by earthquakes. Lava and e asthiC u s least resistance, till . th rent where t ere wa d th some pomt on e . bstructed by ejections an . e the first aperture becommg o. fi es burst open in successiOn, consolidation of lava, ot~~r or~ c Von Buch found that along the line of the ongmal ~dsure. hich lava had issued; each crater was 1o wes t on that Sl eh odn wa nd were w.it ho u t an y but some craters were not breac e 'en fissures, out of which lava-streams. In on~ of. th~~;;;:~s~J the thermometer to 145o hot vapours rose, which m bl t the boiling point lower down. Fahrenheit, and was proba y a. t f aqueous vapour, yet they The exhalations seemed to consi~ ocrevices were encrusted on could not be pure steam, for t e VOLCANIC ERUPTlON IN LANCEROTE. 383 either side by siliceous sinter, {an opal-like hydrate of silica, of a white colour,) which extended almost to the middle. This important fact attests the len<Yth of time durin()' which chemi- c b cal processes continue after eruptions, and how open fissures may be :filled up latera11y by mineral matter, sublimed from volcanic exhalations. The lavas of this eruption covered nearly a third of the whole island, often forming on slightly inclined planes great horizontal sheets several square leagues in area, resembling very much the basaltic plateaus of Auvergne. One of the new lavas was observed to contain masses of olivine of an olive-green colour, resembling those which occur in one of the lavas of the Yivarais. Von Buch supposes the great crystals of olivine to have been derived from a previously existing basalt, melted up by the new volcanos, but sufficient data are not furnished for warranting such a conjecture. The older rocks of the island consist, in a great measure, of that kind of basaltic lava called dolerite, sometimes columnar, and of common basalt and amygdaloid. Some recent lavas assumed, on entering the sea, a prismatic form, and so much resembled the older lavas of the Canaries, that the only geological distinction which Von Buch appears to have been able to draw between them was, that they did not alternate with conglomerates, like the ancient basalts. Some modern writers have endeavoured to discover in· the abundance of these conglomerates, a proof of the dissimilarity of the volcanic action in ancient and modern times; but this character is more probably attributable to the difference between sub~ marine operations and those on the land. All the blocks and imperfectly rounded fragments of lava, transported, during the intervals of eruption by rivers and torrents, into the adjoining sea, or torn by the continued action of the waves from cliffs which are undermined, must accumulate in stratified breccias and conglomerates, and be covered again and again by other lavas. '!'his is now taking place on the shores of Sicily, between Catania and Trezza, where the sea breaks down and covers the shore with blocks and pebbles of the modem lavas of Etna; and on parts of the coast' of Ischia, where numerous currents of trachyte are in like manner undermined in lofty precipices. So often then as an island is raised in a volcanic |