282 Mr. P. J. Martin on the Anticliniil Line of 



as before said, in the Geological Transactions of 1845. Mr. 

 Hopkins calls it an " anomalous dislocation/' and thought with 

 me that it was connected with the river fissure. Although I 

 ^escribed and gave a rude figure of this dislocation in the memoir 

 above mentioned, I did not, up to the time of showing it to 

 Mr. Hopkins, tlioroughly understand its true nature and the 

 manner of its production. I will endeavour to make it better 

 understood. In this part of Sussex the river Arun takes its 

 course in a direct line from tlie older strata in the centi-al line of 

 elevation, through the newer strata to the sea; and the gaps in 

 the escarpments of the lower greensand and of the chalk are 

 directly opposed to each other, although ten miles apart, and 

 constitute a remarkable feature in this part of the country. Much 

 study of this long line of transverse fracture has convinced me 

 that it is the result of the compound operation of a slight anti- 

 clinal divergence, and also of a slight change of the general 

 southerly dip. The first is shown in a sand-bank at Stopham 

 Bridge ; the second by the immediate advance, west of the river, 

 of the greensand country two or three miles into the Wealden 

 area, beyond the greensand country on the east. 



It is on the east side or left bank of the river at Pithingden 

 Farm that the extraordinary slope above spoken of occurs. The 

 surface line of the country rises very nearly in the line of dip to 

 about 250 feet above the river, and then drops, generally with 

 a sharp escarpment, into the Weald clay valley below. But 

 as it approaches the river-gorge, and at the angle formed by 

 the intersection of the two lines of longitudinal and transverse 

 escarpment, the hill slopes gently down over a space of about 

 twenty or thirty acres of ground ; and by the disclosures of a 

 hollow way on the side of the hill and of the stone quarry at the 

 top (seen by Mr. Hopkins, as above mentioned), we learn that 

 this slope is formed by the breaking down of the great tabular 

 masses of sandstone, of which all the plateau of the lowest bed 

 of greensand in this line of country is composed. The rents 

 which answer to this uncommon deflection from the ordinary 

 line of dip are to be seen in the stone quarry, in the hollow road 

 aforesaid, and at the top of the hill where the fall commences. 

 For a long time I was inclined to think that this phsenomenon 

 was the result of a sliding down of these stony strata at the 

 moment of the disruption of the river fissure. But this expla- 

 nation was not satisfactory, and gave place to a better, and I 

 doubt not, the true one. 



In consequence of some inquiries of Dr. Fitton, when he was 

 engaged in his exposition of the extension of the Atherfield beds 

 along the greensand escai-pment of the Weald, I was led to dis- 

 cover that in all this line of countiy the representatives of the 



