ESSAYS 3i5 



Upheaval. A glance at the conditions, under which this island is supposed to 

 have existed, will show that this position is quite untenable. All the strata, from 

 the Hastings Beds to the Chalk, bear witness that a series of undulatory move- 

 ments of the sea-level took place during their deposition, with a general balance 

 in favour of greater and greater submergence. This is part of a world-wide series 

 of changes, which, by the time the Chalk was deposited, produced all over this 

 area, and for miles beyond it, a sea of considerable depth, and evidently far 

 removed from any land surface ; and it may be affirmed, without fear of con- 

 tradiction, that it is impossible for an island to have existed within a few miles of 

 the present escarpments without some of its sands and clays being washed down 

 into the Chalk and thereby altering its composition. 



It is, however, only fair to say that Major Marriott has privately informed me 

 that an island is not essential to his hypothesis, and that a submerged bank will 

 serve as well. But even with this important modification the theory is open to the 

 general objection that the Weald does not stand alone, and that there are many 

 other anticlines from which, as most of us believe, the Chalk has been removed. 

 It is these that form, by analogy, one of the prima facie obstacles in the way of the 

 planation hypothesis ; but they are even more formidable to the submerged bank. 

 In the south we have the Isles of Wight and Purbeck, in which the Chalk attains 

 a thickness of 1800 ft. or more, and at times stands almost vertical ; so that, on 

 any hypothesis, vast quantities must have been removed ; and further north we 

 find the series of Vales of Pewsey, Ham, and Kingsclere, of which the two last 

 are of very minute dimensions. Now, either the' Chalk once covered these anti- 

 clines, or it did not : if the former, we must admit a removal of it on such a vast 

 scale as to undermine the very foundations of Major Marriott's Wealden theory ; 

 if the latter, then he must show us how a submerged bank is to be fitted into the 

 tiny Vales of Ham and Kingsclere, the Greensand inliers of which are only four 

 and five miles long respectively. 



But the real test of all such theories is not so much their prima facie 

 probability, as the degree to which they explain existing facts ; so we will pass 

 on to consider those features which Major Marriott regards as proofs of his 

 hypothesis (p. 592). 



(1) "The absence in the area of the Weald of flints, the product of the chalk, 

 except in the neighbourhood of the escarpments." From further remarks on 

 p. 598 it would seem doubtful whether Major Marriott was aware that both 

 Ramsey and Topley had noted this distribution and accepted it as evidence in 

 favour of planation. As figs. 2 and 3 show, both theories reduce the amount of 

 Chalk to be removed by subaerial forces to a mere wedge, the thick part of which 

 corresponds with the escarpment, while the width depends in the one case (fig. 2) 

 on the gradient of the hypothetical bank, and in the other (fig. 3) on the angle 

 formed by the dip of the strata with the marine plain, or, in other words, on the 

 amount to which the strata were tilted before planation. In the latter case 

 the Lower Chalk rests conformably on the Upper Greensand throughout, and, as 

 shown in the diagram, the wedge may not even yet be so completely removed 

 as to expose the full thickness of the Chalk ; but on Major Marriott's theory there 

 is unconformity all across the floor of the wedge, and therefore the whole of it 

 would have to be removed before existing relations of the strata could be estab- 

 lished. But if, as he supposes, the surface of the Chalk has undergone little or 

 no erosion, then the full thickness of it (600 — 1000 ft.) should be exposed at the 

 escarpment, where, as a matter of fact, we seldom find more than half this 

 amount. 



