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Show 386 NEW ISLANDS IN TilE GULF OF SAN'rORIN. trary, they present a hjgh and steep escarpment towards the centre of the inclosed space. The gulf, therefore, is nearly on aU sides environed by precipices; those of Santorin, which form two-thjrds of the circumference, being two leagues in extent, and in some parts three hundred feet high. These rocky cliffs plunge at once into the sea, so that close to the shore soundings are only reached at a depth of ejght hundred feet, and at a little distance farther at a depth of one thousand feet. In the middle of this gulf, the small isle of Hiera, now called Pa1aia Kameni, rose up, 144 years before the Christian era. In 14~7 this isle received new accessions. In 1573 the Little Kameni was raised in the middle of the basin, its elevation being accompanied by the discharge of large quantities of pumice and a great disengagement of vapour. Lastly, in 1707 and 1709 the New · Kameni was formed, which still exhales sulphureous vapours. These isles are formed of rocks of brown trachyte, which has a 1·esinous lustre, and is full of crystals of glassy felspar. Although the birth of New Kameni was attended by an eruption, it is certain that it was upraised from a great depth by earthquakes, and was not a heap of volcanic ejections, nor of lava poured out on the spot. There were shells upon it when it first appeared; and beds of limestone and marine shells are described by several authors as entering, together with igneous rocks, into the structure of other parts of this group. In order, therefore, to explain the formation of such circulat· gulfs, which are common in other archipelagos, Von Buch sup· poses, and Humboldt adopts the same opinion, that. the different beds of lava, pumice, and whatever else may be mterstratified, were first horizontally disposed along the floor of the ocean. An expansive force from below then burst an opening through them, and, acting towards a central point, rai'sed symmetrically on every side all which resisted its action.' so that the uplifted strata were made to dip away on all std.es from the centre outwards, as is usual in volcanic cones, whtle a deep hollow was left in the middle, resembling in all essential particulars an ordinary volcanic crater. . In the first instance we should inform the reader, that this theory is not founded on actual observations of analogous effects produced by the elevating forces of earthquakes, o: the escape of elastic fluid::; in any part of the globe ; for the mfla .. • THEORY OF E L'EVATION CRATERS. 387 twn from below of tl k 0 h ' le roc s m th l . t e eruption of Jorullo , e Pam of Malpais, during proposed, long after that' \\as, ~s before stated, an hypothesis h w l.C h a d mi. t of a very d'ffi eruptiOn ' to account .Jl.'O r appearances f J 1 erent exp1a t' n . . . o orullo, there was no na Ion. estdes, m the case the centre. All our grde at " cra t ei. 0 f e1 e vat1. 0n'' formed in favour of the origin ofm o ern an a1 o gi·e s, t 11 erefore, being in t . cones and crate 1 . l wns, we are entitled t . . rs exc ustve y by entp-b o scruhmze w'tl . t e new hypothesis . and h . . I I no small severity . ' we ave a right t d .s tratlve evidence' that kn own an d ordm. o emand demon- Insufficient to produce tl b ary causes are perfectly B 1e o served ph uch and Humboldt {I . • enomena. Had Voll. . ' or mstance 111 tl extensive travels which d eserve dl y ' rend let hc o. urse . o.f those r~gard to all volcanic operations of hi . er ~lr opmwns, in smgle cone composed exclu . I' f gh .authonty, discovered a . sz ve y o marme o . l . wzthout a fraO'ment of an . . I acustrme strata, centre a gre:t cavity, e:Ciife~=~~ rock ~nt.er.mixed; and in the then we should have b y a pteCipttous escarpment. een compelled t ' the cone and crater-like confiO'ura . a once to concede, that formation, may sometimes h b bon' whatever be its mode of nary volcanic eruptions. ~ ave no reference whatever to ordi- But it is not pretended that on tl a single example of this kind ~an bele ':hole face of the globe, and North America thousands of s p~mted out. In Eurqpe have been examined com d f qu~re leagues of territory been elevated to va:ious h~:ehtso man?e strata, which have thousand feet above the J l gf h' sometimes to more than ten b eve o t e sea so t' · · ta ular masses· in oth . ' me trues m honzontal f ' er cases With eve d f. . rom the horizontal to th . I ry egree o mclmation, W· ithout great de. e vertlca . so rne 1la ve b een moved Iangement, others l b torted, or shattered with th t . lave een rent, con-districts, at others s 11 e u most VIOlence. Sometimes large position. yet, ami:~ t~rea~es, appear to ha:e changed their these rocks have b b' Innumerable accidents to which een su ~ect ne h h form, exactly represent' ' I vcr ave t ey assumed that with a great cavit . tlmg a arge truncated volcanic cone be ] I.e vc that whenYe m 1Ie centre A h ' 0 • re we t en called upon to ver e astlc fluid d . ranean regions burst th I l . s generate m the subter-them in the peculiar roug 1 lorzzontal strata, so as to upheave select, as if from ch . man~er before adverted to, they always OICe, t ose spots of comparatively insignifi- 2C2 |
