42 Prof. BucKLAND and Mr. De la Beche on the 



sand and chalk near Charmouth^ Lyme, and Axminster. But as no such 

 arches exist in the Vale of Weymouth, nor any such continuity of the green- 

 sand strata in the vales of Bredy and Bridport, we cannot but infer that 

 some adequate cause has produced the removal of the vast masses of materials 

 which apparently must once have filled the spaces that are now left void ; and 

 we see no cause adequate to the production of such an effect, except the 

 denuding power of a mass of moving waters ; a power which has removed 

 more than it has left of the entire bulk of nearly all the strata that appear on 

 the surface of this district, excepting the chalk. 



Again, if we look for traces of ruin and violence on the surface along the 

 lines of fault, we find no such indications presented to us ; but however great 

 may have been the dislocation and subterraneous changes of level, the out- 

 lines of the surface are little affected by these changes : thus, our sections 

 PI. II. fig. 1, 2, 3, 4, 5, and 6, affbrd examples of the summits and sides of 

 hills where we should be utterly unconscious, from the external form of the 

 land, that the least derangement or fracture has ever affected the subjacent 

 strata ; the general outlines are regular and rounded, as if no violent move- 

 ments had ever occurred below, and all the ruins and piles of rubbish that 

 must have been produced along the lines of elevation and fracture are swept 

 clean, clear, and smooth away. 



If we traverse the great Ridgeway fault for fifteen miles, from one extre- 

 mity to the other, we see along the whole surface scarcely an indication of its 

 existence. Near Upway we have an obvious example of this fact, at the point 

 where the road from Bridport passes down the chalky escarpment of the 

 Ridgeway through one of those broad and sweeping dry combs which are so 

 common in escarpments of chalk : having descended nearly to the bottom of 

 the hill, where we should expect the outcrop of inferior chalk or greensand, 

 we are surprised to find Portland stone rising to the north, and abutting against 

 the chalk ; yet we see not the slightest change in the outline of the surface on 

 either side of this line of fault, nor is there upon its south side a single remain- 

 ing fragment of all the masses of greensand and chalk that must have been 

 elevated into a new and high position on that side of the fault when the frac- 

 ture took place ; all traces of the enormous ruins that attended this great 

 convulsion have utterly vanished and been swept away ; so that scarcely the 

 residuum of an outlying fragment remains to attest the catastrophe that has 

 taken place : the sloping sides of the combs glide regularly and gently down, 

 as if they had been excavated in one undisturbed and uniform mass of con- 

 tinuous chalk. Nor is this outclearing and total removal of the broken frag- 

 ments peculiar to this comb on the north-west of Upway ; it is equally ap- 



