4 Mr. Hopkins on the Structure of the 



these escarpments at Folkstone and Wissant, as well as those at Beachy Head and 

 the southern point of the Bas Boulonnais. Thus connected, the English and the 

 French districts, with the intervening portion of the Channel, would form a tract 

 which may be described generally as an elongated oval, but having a curvilinear 

 instead of a rectilinear axis. Its length is about 150 miles, and its greatest breadth 

 about 40 miles. 



Before I proceed to the particular description of phaenomena, it may be desirable 

 to explain the precise sense in which I have used certain expressions in this paper. 

 There are frequent instances in the Wealden district in which the section of a 

 longitudinal elevation is such as represented in the annexed diagram, the beds 

 dipping (and in many cases with great rapidity) in one direction, but preserving a 



sensible horizontality in the opposite one. This is obviously not an anticlinal 

 arrangement, nor can the line from which the descending dip commences be termed 

 with propriety an anticlinal line. I have called it a line of flexure, finding it almost 

 essential to employ some distinctive term to denote it. All anticlinal and synclinal 

 lines, lines of flexure, of fault, &c., I have frequently designated by the general 

 term of lines of elevation. 



I shall now commence my description with an account of the central range of 

 the Wealden district, consisting almost entirely of Hastings Sand. 



Hastings Anticlinal Line. — A well-defined ridge, forming the most striking fea- 

 ture in this part of the district, runs from Battle to the north of Hastings. The 

 Hastings anticlinal line may be traced with great precision from within a mile of 

 Battle to the coast. It appears to lie just on the northern side of the summit of 

 the ridge, and runs in a straight line to meet the coast at a point south-east of 

 Fairlight church. The northern side is the best defined, owing to the rapid dip of 

 the beds on that side, which in some places is not less than 50° or 60° in a direc- 

 tion perpendicular to that of the ridge. On the southern side the average dip, 

 though considerable, is not nearly so great. The point where this line meets the 

 coast is well defined in the splendid natural section which the cliffs afford. It 

 should be observed, however, that the general direction of the coast makes an 

 angle of about 45° with that of the anticlinal line, and therefore makes about the 

 same angle with the line of greatest dip, so that the apparent dip of the beds in 

 the cliff" is much less than their real dip. It is not however very great, and is 

 much more regular than in the neighbourhood of Battle. I could not trace the 



