248 C. E. De Ranee — Deposition of Cretaceous Strata. 



East Compton and Winterbome Abbas, being partly brougbt up by 

 faults. The escarpment of the Chalk, with the Upper Greensand at its • 

 base, runs almost continuously from Eggardon, by Askerswell, Long 

 Bredy, Little Bredy, to Abbotsbury Common, where it terminates 

 against a large fault running East, which brings up the Oolites, as 

 shown on the Geological Survey Map, Sheet 17. The fault, how- 

 ever, runs along the higher part of the Chalk escarpment for its 

 greater portion, and the top of Greensands appears from Bincombe to 

 Poxwell. Southward and westward of this fault the Oolites strike 

 nearly East and "West, and the beds are often repeated by " strike 

 faults " running in the same direction, which are evidently of Post- 

 Cretaceous age. In the tract between Abbotsbury and Weymouth 

 Bay the repetition of the beds is due to several W.N.W. anticlinal 

 and synclinal rolls, the tops of which appear to have been worn into 

 one uniform plain of marine denudation, sloping from the W.N.W., 

 on the surface of which the Upper Greensand vs^as deposited. West- 

 ward from Burton Bradstock the Oolites and Lias dip steadily to the 

 south-east, bringing up higher and higher beds, on the eroded edges 

 of which rests the Upper Greensand, which further inland is sur- 

 mounted by the Chalk. In addition to the East and West faults 

 traversing the Oolites, there are a great number of faults running 

 about N. 30 E., which cut off and are evidently of later date than the 

 former system. 



The subsidence in the strata before the deposition of the Cretaceous, 

 pointed out by the anticlinal and synclinal rolls in the Oolitic strata, 

 if commencing at an era when the whole of the west of England 

 stood well above the sea-level, would oifer exactly the conditions as 

 the curved surface of the ground sunk beneath the waves to produce 

 a plain of marine denudation, which Professor Eamsay has demon- 

 strated must be the invariable result " when a country is gradually 

 sinking, and the rate of waste by the waves on the shore (as it were 

 slowly entering into the country) be proportionate to the rate of 

 sinking." ^ 



The direction and inclination of such plains of ancient date will 

 have been more or less modified, by curvature caused by subsequent 

 subsidences, and by faults the result of more recent elevations. And 

 even now modern plains may have been locally modified in direction 

 by the strata attacked by the waves not having been always de- 

 posited horizontally, but inclined at small angles around islands of 

 older rock left by still older denudations, or brought up by faults 

 and flexions. Thus in the south of England Mr. Prestwich, F.K.S., 

 in his address to the Geological Society on resigning the President's 

 chair, describes the great ridge of Palseozoic rocks which is believed 

 to pass beneath the Secondary rocks from the Ehine to South Wales, 

 connecting tlie old rocks of the Ardennes with those of the Mendips, 

 bringing up Coal-measures in detached basins on its northern flanks, 

 and probably also on the south, as is believed by Mi". Godwin-Austen, 

 who worked out the question in 1856. 



From these facts it is clear that in advancing from Lulworth to 



1 Physical Geology and Geography of Great Britain. Fourth Edition. 



