Vol. 65.] GEOLOGY OP THE NEIGHBOURHOOD OE SEAEOED. 447 



also indicated by other fossil evidence. Similar results are obtained 

 in several other exposures round the base of the hill, both in 

 Poverty Bottom and on the western face of Mount Pleasant. On 

 the top of the hill another pit shows clearly the zone of Actino- 

 camax quadratus, for Cardiaster pillula, the gibbous form of 

 Echinocorys, and bryozoa occur. A well-marked band of Ecliino- 

 corys occurs in this pit. At a slightly lower level, a pit on the 

 western face is full of conspicuously pyramidate forms of Echino- 

 corys. This is evidently near the top of the Marsujpites-Zone, 

 which clearly runs beneath the summit of the hill near the 200-foot 

 contour on either side, and crosses it towards the north above 

 Denton. Following this band along the western slope of the ridge, 

 and gradually descending in level with the dip of the strata, we 

 come to a small exposure below Rookery Hill, near the house 

 marked ' Foxholes ' on the 6-inch Ordnance map. Here plates of 

 Marsujrites occur at about the 50-foot contour, and confirm the 

 position of this zone on Mount Pleasant. 



Having now secured three separate localities in this area, where 

 the position of the Marsu_pites-Zone is accurately known, the 

 theoretical outcrop can be mapped by the usual graphic method 

 upon a contoured map. By this means the probable position of 

 this zone around Bishops! one village and Norton is at once indi- 

 cated, and the probable strike and dip of the beds are thus found. 

 It remains only to confirm this mapping by further observation in 

 the field. There are several small exposures near Bishopstone 

 village, which thus fall into the zone of Actinocamax quadratus 

 near the base of that horizon. This conclusion is confirmed by the 

 abundant occurrence of Cardiaster pillula, Rliynchonella plicatilis. 

 and gibbous forms of Echinocorys scutatus. 1 A further confirmation 

 is afforded by the fact that the 200-foot strike-line on the graphic 

 diagram, continued eastwards, skirts the ridge of Cradle Hill, and 

 cuts Hindover close to the level where numerous Marsujoites-jAaAes 

 were found. 



It is thus proved that in this area the beds are dipping uni- 

 formly at an angle of 1 in 30, or about 2° towards the south-west, 

 and that they are not here affected either by faults or by flexures of 

 appreciable magnitude. The Marsupites-Zone at Foxholes cottage 

 dips below the alluvium, and is not seen again east of the Ouse 

 Y alley. On the west, however, it was found by Dr. Howe, emerging 

 from beneath the cliff between Old Nore Point and Friar's Bay. 

 The general contour of the country above described is shown in the 

 accompanying diagrams (figs. 2 & 3, p. 448). It remains now to link 

 up this evidence with that furnished by the known exposure in Sea- 

 ford Cliff. Between Hindover and Seaford Head, along the western 

 slope of the Cuckmere Valley, there are very few exposures of any 



1 I have since found direct evidence of the Marsupites-Zone in the valley 

 east of Bishopstone, where a small cutting near the barn yielded brachial 

 ossicles of Marsupites or Uintacrinus (from its position probably the former). 



