"Vol. 69.] A PALAEOLITHIC HUMAN SKULL IN SUSSEX. 119 



the brown and red flints and the h'onstone gravel are to he seen 

 ■overlying- the plough-lands in all directions. 



At Piltdown the gravel-bed occurs beneath a few inches of the 

 surface-soil, and varies in thickness from 3 to 5 feet ; it is deposited 

 upon an uneven bottom, consisting of hard yellow sandstone of the 

 Tun bridge Wells Sands (Hastings Beds). It is composed for the 

 most part of dark-brown Wealden ironstone pebbles, but is mixed, 

 to the extent of about a sixth of the mass, with angular brown 

 flints, a large proportion of which are tabular in form. 1 Occasional 

 cherts and quartzite pebbles also occur, but there are no 

 recognizable Eocene pebbles. 2 The flints vary from 6 or 7 inches 

 in length by 3 or 4 inches in width, down to a very fine gravel or 

 sand. Portions of the bed are rather finely stratified, and the 

 materials are usually cemented together by iron oxide, so that a 

 pick is often needed to dislodge portions — more especially at one 

 particular horizon near the base. It is in this last-mentioned 

 vstratum that all the fossil bones and teeth discovered in situ by us 

 have occurred. The stratum is easily distinguished in the appended 

 photograph (PI. XV) by being of the darkest shade and just above 

 the bed-rock. 



The gravel is situated on a well-defined plateau of large area, 

 lying above the 100-foot contour-line, averaging about 120 feet 

 at Piltdown, and lies about 80 feet above the level of the main 

 stream of the Ouse. The river has cut through the plateau, both 

 with its main stream and its principal branch, which is called the 

 Uckfield Paver. 



Speaking generally, the remains of this plateau, of which that at 

 Piltdown is merely a part, can in places be traced along a line 

 drawn through Lindfield, Sheffield Park, Buckham Hill, Uckfield, 

 and Little Horsted and southwards, broadening outwards towards 

 the Chalk Escarpment. In fact, the whole country lying between 

 the base of the Wealden Anticline and the Chalk Escarpment 

 presents the appearance of one large low plateau or former base- 

 level plane dissected by the Ouse and its tributary streams. 



Remnants of the flint-gravels and drifts constantly occur above 

 the 100-foot contour-line, and upon the slopes, down which they 

 a,re trailing towards the river and streams. 



These flint-bearing gravels and drifts have not been mapped or 

 otherwise recorded before in the Ouse Valley, north of the boundary 

 between the Wealden Clay and the Hastings Beds, which runs 

 immediately south of Isfield. Up to the latter point they are 



1 There is a tendency among these tabular flints to weather into a prismatic 

 or polyhedral form. One specimen shows a column 2 inches in length. The 

 prismatic structure is well shown in figs. 2, 6, 7, & 9 of PI. XVII. Most of 

 the nodular flints, formerly existing, appear to have disintegrated. 



2 JJr. J. V. Elsden writes that Tertiary pebbles are found in the Ouse gravels 

 on the south near Lewes. Eocene pebbles occur in a thin bed east of the Race 

 Stand, on the hill above Lewes ; and a similar band is to be seen about 15 feet 

 down the cliff, near the Coastguard Station at Newhaven. See Q. J. G-. S. 

 vol. xliii (1887) pp. 646-47. 



