SECTIONAL TRANSACTIONS.— H. 467 



of gravel although they were separated by a distance of 8 yds. The 

 associated animal bones, Elephas antiquus, Rhinoceros, etc., indicate inter- 

 glacial conditions, and the sequence of Acheulean implements recovered 

 brings to light the fact that the Bamfield deposits are earlier than those 

 gravels at a higher base level in Pearson's Pit, Dartford Heath. 



The Barnfield deposits are the infilling of a stranded river 1,400 ft. in 

 width, with a base level of about 73 ft. O.D., whose channel was cut prob- 

 ably in the pre-Boyn Hill Erosion Stage. In it is preserved an ascending 

 sequence of terraces. 



Lower Gravel Aggradation. Clactonian. 



Older Middle Gravel Aggradation. Abbevillian (?) to 



Middle Gravel Erosion Stage. Acheulean. 



Later Middle Gravel Aggradation. Acheulean. 



Upper Loam, and later still. • Acheulean. 

 New Craylands Pit Stage. Twisted ovate. 



The precise position of the Swanscombe skull was at the commencement 

 of the Middle Gravel Erosion Stage, and it was found in the first obhque 

 bank left stranded as the waters became rejuvenated to cut a fresh channel 

 from the surface of the Older Middle Gravels (the habitation level of Swans- 

 combe Main) down through the Lower Loam and Lower Gravels to touch 

 the Thanet Sand at about 73 ft. O.D. 



The depth of the subsequent aggradation from this level 73 ft. O.D. 

 to that of the surface of the deposits at Dartford Heath represents the 

 pre-Boyn Hill status of the Swanscombe skull horizon. 



The still later excavation of the valleys of the Darent and Cray, and of 

 the formation of the descending terraces of the Lower Thames completes 

 the picture of the age of the Swanscombe skull. 



A sub-plenal evolutionary stage of human development is evidenced by 

 the skull, perhaps best shown by the features of the endocranial cast. The 

 cranial capacity is estimated at less than 1,100 cc. (1,065 cc. from the 

 restored endocranial cast A.T.M.). It is considered by the writer that 

 the bone contacts at the antero-inferior and the postero-inferior angles 

 of the parietal bone indicate the sub-plenal stage of the flexion of the cranial 

 base ; that the plane of the foramen magnum looked downwards and 

 backwards ; and that there was a certain amount of proclination of the head. 

 The shortness of the basilar process and the form of the pharyngeal tubercle 

 are distinctly human and non-anthropoid features. 



Prof. W, B. R. King. — The geological evidence (10.30). 



The fact that the Swanscombe skull was found in a deposit which is 

 part of the Boyn Hill or loo-ft. Terrace of the Thames adds greatly to its 

 importance. 



The fluviatile deposits of this terrace are divided into an upper and a 

 lower part, separated by a period of erosion, but both parts yield the same 

 general type of mammalian fauna, which is also found in the Clacton channel 

 at lower levels. 



This is interpreted as showing that the river after depositing the lower 

 gravels cut down and formed the Clacton channel, but later aggraded its 

 bed again to lay down the higher (skull-bearing) gravel. 



The fauna indicates a temperate climate. On the north of the Thames 

 in Essex the gravels of this terrace rest on a spread of boulder clay referred 

 to the Great Chalky or Chalky Jurassic Boulder Clay of the Great Eastern 

 glaciation of East Anglia. At a later date valleys were cut through the 



