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ME. J. V. ELSDEN ON THE STJPEEFICIAL GEOLOGY OF 



(5=1 



with occasionally a very marked stratification. 

 A similar gravel capping is found on the isolated 

 50 feet contour to the west of Amberley, and 

 again at Houghton, while, within the gorge, the 

 gravels of North and South Stoke, and the 

 mammaliferous gravel at Peppering, 80 feet 

 above the present level of the Arun, have already 

 been sufficiently noticed *. 



At Greatham, on the left bank of the Arun, 

 the gravels differ chiefly from those just described 

 in containing very much less chert. Chert, in 

 fact, as a prominent constituent of the gravel, 

 is confined to the right bank of the river, which is 

 in striking harmony with the difference in com- 

 position and texture of the Greensand beds lying 

 to the west of the river, where a brittle and 

 cherty stone succeeds to the compact argillaceous 

 stone of Pulboroughf. 



Gravel extends all along the left bank of the 

 Arun from Greatham through Rackham to Wig- 

 gonholt and Wickfield Bridge, where two small 

 tributary streams, the Chilt and the Stor, join 

 the main river. Near Wiggonholt Common, on 

 the very edge of the alluvium of the Arun, some 

 pits show the following section : — 2 feet of white 

 sand, with few or no flints, resting on a narrow 

 band, 6 inches in width, of dark sand. Below 

 this are 4 feet of sandy gravel, with small an- 

 gular flints and large lumps of ironstone. On 

 the summit of Wiggonholt Common, at a height 

 of 132 feet above the river, the surface-deposit 

 consists of a thin coating of angular flints, with 

 a little ironstone, but no chert fragments. Traces 

 of rude stratification are seen in this gravel in 

 some of the sections, and the level is nearly 

 the same as the highest gravel of Pi ttle worth 

 Common, on the opposite side of the river. 



The gravels of the Stor, near Hurston, are an 

 instructive example of the denudation effected 

 by this small stream (see fig. 3). On each side 

 of the river beds of gravel occur, extending 

 above the 50 feet contour. There can be no 

 doubt that these are old river- gravels of the 

 Stor. At Redford sections are seen showing 

 about 5 feet of ferruginous sandy gravel with 

 contorted stratification. In the lower parts flints 

 are small and scarce, and the sand is finely 



* Mantell, 'Geology of S.E. England,' p. 41. 

 t Martin, ' Geological Memoir on part of W. Sussex, 

 p. 67, 



