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Show 180 OLDRR PLIOCENE PERfOO. [Ch. XIII. . of the local derangements movements have given nse to some f 1' I 1 11 in this formation, parti.c u1 a i· l Y where masses Mo sod Ill1 c 1a dc • • cr Thus, between un es ey an Pierce as It were, the crab. . · d · 1 Trimm' inO'ham we see t h e app·e arances exhibi.t e m t 1e accom- · • 0 . N 41) The chalk, of which the strata are Panymg view ( o. · b hi.r rhly m. clm. ed, or vei· tI' Ca] ' proJi ects in a promontory, ecause 0 it offers more resi• stance t 0 the action of. the waves than the terti.a ry beds wh I' c 11 , on b °t h sides ' constitute. the w.h ole of the cliff. T 11 e I1 e1. g1 1 t of tlle soft craOo' strata Immediately. above the chal k I·S , 1·1 1 t hI' S p ]ace ' about 130 feet. Those whiCh are m· contact (s ee t 11 e woo d-cut) are inclined at an angle of 4. 5", and appear mm .e dI'S turbed than in other parts of the• chffs, as 1' f t h ey 11 au.1 b ee· n displaced by the movement by wluch the chalk was protruded. Very similar appearances are exhibited by the northernmost of the three protuberances of chalk, o~ which a front ~icw is gi·V en m· tl 1e an nexed diagram · . It occupies a, space of. about 100 yards along the shore, and proJects a~out 60 yards m advance of the general line of cliff. One of 1ts edges, at c, rests upon No.42. Nortltern protuberance ofchalll, T•·irnminglwm. a ", ',11 a ll c w1' tl1 n·1 11 t s. c. Laminaleu blue clay. b: Gravel, of broken and half-rounded flints. d. Sand and yellow loam. the blne clay beds of the crag, in such a manner as to imply that the mass had been undermined when the crag w~s deposited, unless we suppose, as some 11 ave done ' that th1s chalk is a great detached mass enve1 o pecl bY crao(1'. For, Ch. XIII.] CRAG. H:H as one of the 'Needles', or insulated rocks of chalk, which projected 120 feet above high water-mark, at the western extremity of the Isle of Wight, fell into the sea in 1772 *, so a pinnacle of chalk may have been precipitated into the tertiary sea, at a point where some strata of the crag had previously accumulated. 'l'he beds of flint and chalk in the above diagram appear nearly horizontal, but they are in fact highly inclined inwards towards the cliff. The rapid waste of the Norfolk coast might soon enable us to understand the true position of this mass, if observations and drawings are made from time to time of the appearances which present themselves. Perhaps it may be necessary to suppose, that subterranean movements were in progress during the deposition of the crag, and the extraordinary dislocations of the beds, in some places, which in others are perfectly regular and horizontal, may be most easily accounted for by introducing an alternate rise and depression of the bed of the sea, such as we know to be usually attendant on a series of subterranean convulsions. Several of the contortions may also have been produced by lateral movements. Passage of ma'rine crag into alluvium.-By supposing the adjoining lands to have participated in this movement, we may explain the origin of those masses of an alluvial character which . contain the detritus of many rocks, the bones of land animals and of drift timber, which were evidently swept down into the sea. 'l,he Jand-floods which accompany earthquakes are, as we have seen, capable of transporting such materials to great distances i', and, as part of these alluviums must be left somewhere upon the land, we may expect to find, on exploring the interior, a gradual passage from the terrestrial alluvium to that which was carried down into the sea, and which alternates with marine beds. The fossil quadrupeds imbedded in the crag appear to be the same as those of a great part of the alluviums of the interior • Dodsley's Aunua.l llrgister, val. xv. p. 140. t Vol. i. clwp. 25. |