16 Mr. Hopkins on the Structure of the 



Midhurst Line of Flexure. — A line exactly similar to the one just described, and 

 sufficiently well defined, passes by Sellham and Midhurst to Trotton Common. A 

 north and south section, however, across this line differs from the above section in 

 the absence of the anticlinal disposition of the beds there represented at (A). The 

 beds rise to the line of flexure (B) directly from the chalk. 



This line ranges exactly with the Pulborough line. They both appear to me to 

 belong in fact to the same line, as represented in the map. Mr. Martin however 

 appears to think, that what I have termed the Midhurst line is a continuation of 

 the Greenhurst anticlinal line, which he supposes to take a north-westerly direction 

 from the point where I have considered it to terndnate, nearly in the direction of 

 the river, to Sellham. There cannot, 1 conceive, be any very positive evidence of 

 the junction of these two lines, and therefore I have preferred the view above 

 given respecting them. The difference however between this view and Mr. Mar- 

 tin's is of no importance whatever, 



Lewes Anticlinal Line. — In the chfFs and chalk-pits north-west of Lewes, and in 

 those north-east of it on the opposite side of the river, the upper chalk with flints 

 dips with a rapidity which would, at a comparatively short distance to the south, 

 carry the upper beds of the chalk down to the level of the bed of the river, whereas 

 the chalk hills in that direction, on the opposite side of the chalk valley in which 

 Kingston and Palmer are situated, are nearly as high as the escarpment north-west 

 of Lewes. There must necessarily therefore be either a fault, or a rise of the beds 

 to the north from a synclinal line, by which the chalk about Kingston is brought 

 up to its actual elevation. The complete explanation is given by the natural 

 section on the opposite side of the river near Southerham. The rapid ascent of 

 the beds to the south is there beautifully exhibited. The synclinal line passes into 

 the cliff just about the coombe-like valley (marked in the Ordnance Map) imme- 

 diately north of Southerham, in the insulated chalk hill east of Lewes. It is doubt- 

 less connected with the formation of that valley. The southerly ascent of the beds 

 is seen very distinctly till they meet the valley between the hill just mentioned and 

 the general chalk escarpment on the south of it, where the regular dip to the south 

 is again resumed. The anticlinal line must therefore run along this valley. Mr. 

 Martin has detected farther indications of its continuation to the east, and, for the 

 reason above stated, it is certain that it strikes into the chalk on the west of 

 Lewes. The exact coincidence of the direction of this line with that of the Green- 

 hurst line renders it highly probable that the one is a prolongation of the other*. 



* Dr. Mantell observed these phsenomena in the immediate neighbourhood of Lewes, and has given a 

 section of the chalk chfFs on the east side of the river opposite to the town, in his ' Geology of the South- 

 east of England,' p. 352. 



