352 Superficial Gravels and Clays. [July, 
near Guildford.* In these the nearly perfect skeleton of a 
mammoth was found. Remains of trees occurred, rooted 
in the underlying Neocomian clay, the whole being overlaid 
by the subangular valley gravels. 
To this period belongs most of the flint implements of 
the Thames Valley gravels. When found in the gravels 
they are mostly worn by rolling, but at Adton in the deposit, 
described by Colonel Lane Fox, below the gravel they were 
quite unrolled just as Mr. Godwin Austen found the unin- 
jured bones of the mammoth in a similar situation at Pease 
Marsh. 
The localities where the flint-implements occur in most 
abundance are just such as might have been chosen by 
palaeolithic man if the configuration of the country was 
then the same as it is now. Perhaps the most conspicuous 
instance of this is the Milford Hill Station near Salisbury. 
Milford Hill is described by Dr. Blackmore as forming a 
buttress between the two valleys of the Bourne and 
the Avon above their junction. It is separated from 
the main tradt of high land behind by a transverse 
valley, thirty feet in depth, so that it forms an isolated hill. f 
Such a position was an admirable one for a rude tribe de- 
pendent for their living on hunting and fishing; giving them 
the command of two valleys, and being easily defended 
from attack. In our own distridt it is noticeable that the 
implements are found in greatest abundance in situations 
presenting somewhat similar features. Thus at and near 
Mill Hill at Adton numerous flint-implements have been 
discovered in the lower part of the gravel. Mill Hill lies 
between Adton Brook and Bollow Brook, and to the south, 
slopes rapidly down towards the low flat bordering the 
Thames. The locality in Gunnersbury Park, where Mr. 
Crooke obtained many implements, is on the crest of a 
similar slope, and immediately to the east of another small 
brook. In such situations palaeolithic man might easily 
secure himself from the great wild beasts that frequented 
the lower ground near the river ; he held a position of 
defence with regard to other tribes, and the brooks in the 
vicinity would probably be frequented by many of the 
smaller animals the objedts of his chase. Mr. Crooke found 
numerous semi-fpssilised pieces of wood along with flint 
implements in the gravel on the east side of Bollow Brook, 
and it seems not unlikely that these were the remains of a 
stockade that had surrounded the old palaeolithic station. 
* Quart. Journ. Geol. Soc., vol. xi., p. 112. 
f Ibid., vol. xxi., p. 250. 
