AUSTEN — TERTIARY DEPOSITS OF THE SUSSEX COAST. 67 



Dunnose, 792 feet. " Concerning these downs, a singular circum- 

 stance is remarked by the inhabitants of Chale. Dunnose is now 

 about 100 feet above the line of Week Down, " yet old persons affirm 

 that within their remembrance Shanklin Down was barely visible 

 from St. Catherine's;" and that '*old men have told them they 

 knew the time when Shanklin Down could not be seen from Chale 

 Down, but only from the top of the beacon*." 



I examined carefully the whole of the low tract which extends 

 from the sluice at the upper end of Brading Harbour, in order to 

 ascertain whether this e^'idence of depression was confirmed. This 

 tract is now so low that a depression of a few feet would insulate the 

 whole parish of Yaverland ; as it is, the sea is excluded on the side 

 of Sandown Bay by groins, which serve to collect a great shingle- 

 bank. The sluice at Brading, by which the water of the Yar escapes, 

 shows a fall of about 8 feet, which will give 10 feet at most for the 

 elevation of Sandham Levels above low-water. Had there ever been 

 a greater amount of depression at this place, deposits like those of 

 Brading Harbour would be found over it ; that such do not occur is 

 evident from the materials thrown out in forming the deep water- 

 courses. On the other hand, the roots of trees are not uncommon, 

 as if it had at some time been a wooded tract. It would therefore 

 seem that the Sandham Levels now occupy a lower level, with refer- 

 ence to present sea, than they have ever done before. 



4. Pagham Harbour and its neighhovrhood. — In Bracklesham 

 Bay, and off the entrance into Pagham Harbour, at extreme low- 

 water, estuarine deposits, with shells in their positions of life, are 

 to be seen. Taken by themselves, these beds would not indicate 

 change, inasmuch as they might possibly be the remains of certain 

 depressed or estuarine areas at a time before the coast had been cut 

 back to its present outline. Within the area of Pagham Harbour, 

 however, there are sections which show a change like that to be 

 observed at Portsmouth (p. 6.5). A silt-deposit, with bands of 

 Cardium edide, Scrobicularia piperata, sm.d Mactra solida, overlies an 

 old terrestrial surface with trees, which are rooted in the uppermost 

 of a series of beds which must have been part of a marginal sea- 

 zone. According to this section (fig. 6, p. 68) there have been, first, a 

 movement of elevation of beds into subaerial conditions, then a long 

 period of terrestrial surface, and finally a subsidence, followed by the 

 accumulation of estuarine mud (fig. 6, i), which corresponds with 

 the lower deposit (fig. 5, 4) in the Portsmouth section. 



At Felpham, east of Bognor, the order is precisely the samef. 

 The old terrestrial surface at these places indicates depression ; but 

 the overlying deposits show that the area in which they were formed 

 was permanently submerged, whereas it is only very partially so at 

 present ; there has therefore been a movement of elevation. 



In the fourteenth century mention is made of a sudden irruption 

 of the sea on the Selsea coast, and the consequent loss of 2700 acres ; 

 that this was brought about by subsidence, and not by the gradual 



* Worsley (1781), quoted by Englefield, Isle of Wight, &c., p. 44. 

 t See Dixon, Foss. Geol. Suss. p. 31. 



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