TEAKSACTIONS OF SECTION C 695 



tends in an E. and W. direction, forming an angle of about 35° with the line of 

 the present cliff towards Flan^borough Head. The old cliff probably extended 

 along the foot of the Wolds in a semicircle past Driffield to the Humber at Ferriby, 

 and the whole of Holderness east of that line was under water. The old chff at 

 its termination seawards is fully 30 feet in height. Its surface is smooth, and the 

 layers of chalk, ranging up to 2 or 3 feet in thickness, are rounded, exhibitmg an 

 appearance similar to a water-washed surface of mountain limestone. The present 

 cliff offers a marked contrast ; its surface, subject to constant denudation and 

 weathering, exhibits a sharp and angular appearance without any of the polished 

 convexity of the old one. The latter character is very suggestive, Mr. Eeid con- 

 siders, of the action of blown sand ; and the presence of a large quantity of fine 

 rounded sand in the section affords corroborative evidence of the correctness of the 

 opinion. 



The section exposed during the excavation is as follows : — 



Boulder clay 



Blown sand 20 feet inches 



Semi-stratified marl sand and chalk wash . 4 „ 6 „ 



Sea-beach of rounded pebbles of chalk . . 4 „ 6 „ 



The thickness of the latter varies with the character of the chalk floor on which 

 it rests. The latter is uneven and occasionally deeply hollowed. The old beach 

 filled up the irregularities to a common level. 



The lowest bed, which rests on a floor of denuded chalk, consists of well- 

 rounded pebbles of chalk, many of them bored by Pholas, and a smaller^ number 

 by Saxicava. Intermixed are a comparatively small number of fragments in a sub- 

 angular condition, which have probably fallen from the cliff above and suffered less 

 from denudation and attrition. It is marked by an entire absence of travelled 

 rocks derived from the glacial clays which at present extend over the whole of the 

 deposits comprising the old beach. The chalk pebbles are piled up under the cliff 

 and gradually thin out as the mass recedes from it. The present beach is composed 

 of similar chalk pebbles, but is readily distinguished from the old one by the presence 

 of large numbers of stones and boulders of older rocks derived from the glacial 

 clays which envelope the cliffs. In addition to the moUusca named above shells 

 of Ostrea, Littorina, and Purpura have been found. 



The next beds in the series are about 40 feet in thickness near the face of the 

 chalk cliff, and extend about the same thickness for a few feet, after which they 

 become attenuated and gradually disappear, giving place to ' blown sand.' The beds 

 are characterised principally Ly alternations of sandy marl and chalk wash, which 

 have been cemented together "by the percolation of water ; fragments of angular 

 chalk frequently occur mixed in the mass. 



The blown sand, which envelopes the beds last mentioned, extends far up the 

 face of the clifl". It is fine, the grains vary little in size, and are well rounded. 

 The sand appears to have been blown against the face of the clifl", and whilst thus 

 having all the angles worn oft' has also been instrumental in reducing the rough 

 angular surface of the chalk to its present smooth and niammilated appearance. 

 The bed of sand, forming, with the beds below, a triangular mass, is enveloped on 

 the side opposite to the clifl' in a mass of stifl" glacial clay, the lower purple 

 boulder clay reaching from the summit of the cliff" to the beach below. The 

 general arrangement indicates a period, probably pre-Glacial, when the area under 

 the old clifl' was raised above the action of the waves, and the presence of land 

 shells, of the genera Pupa and Helix, which have been found preserved in the 

 cemented chalk wash clearly shows this to have been a land surface. The bones of 

 mammals have also been found in considerable abundance in the same beds, as well 

 as those below and in the quicksands above. With the advent of the Glacial era a 

 great part of the sand would doubtless be removed, but that lel't was protected by 

 the cliff, and the ice-sheet passed over it, leaving the whole covered with boulder 

 clay on its retreat. 



The number of animal remains found during the excavation has been both large 

 and important; amongst others the teeth of Ele2)has primigenius, a vertebra, 



