35 ° 
Superficial Gravels and Clays. [July, 
I have described the main features of my theory in several 
papers published in this Journal and in the “Journal of the 
Geological Society, and I shall now seek to apply it more 
particularly to the deposits described in this paper. To 
render the subje(5t as clear as possible I have drawn up the 
preceding tabular statement, showing the relation that the 
deposits of the Thames Valley bear to the Glacial period. 
F. Lower Brick-Earths. Older Mammalian Fauna. — The 
Lower Brick-Earths are only represented in the Brentford 
district by the small undisturbed patch that I found opposite 
Flora Villas, and by more or less drifted remains of the 
older mammalian fauna. They are more fully developed in 
the lower part of the Thames Valley at Erith, Crayford, 
Ilford, and Grays Thurrock. The depositions of these 
brick-earths in the south-eastern counties was preceded by 
a land surface represented in the rootlet beds of Kessing- 
land, Hasborough, and Runton. 
The fauna found in the deposits is closely related to the 
still older Cromer Forest-bed, by the occurrence of Elephas 
priscus , E. antiquus, Rhinoceros megarhinus, R. hemitcechus, and 
Cervis dama, var. Clactoniensis , amongst the mammals, and 
C.fluminalis and Hydrobia marginata amongst the mollusks. 
R. etruscus, another Cromer Forest .species, has been found in 
beds, apparently of the same age as our Lower-Brick earths, 
in the valley of the Rhine, along with Elephas antiquus. 
In the Thames Valley there are few deposits of this age 
that were not more or less affebted by the cataclysm that 
spread out the middle sands and gravels. The small patch 
found opposite Flora Villas at Brentford, some of the lowest 
beds in the Lea Valley at Clapton, and the Grays Thur- 
rock brick-earths are the only instances I know of where 
the sands appear to be quite undisturbed. The mammalian 
beds at Ilford, Crayford, and Erith are, I think, all slightly 
drifted, and contain some admixture of remains belonging 
to a later date. 
Before the Atlantic ice reached the north-west coast of 
Scotland, the Straits of Dover do not appear to have been 
cut through, and the German Ocean only communicated 
with the Atlantic northward. By the arrival of the ice 
from the north-westward on the coast of Scotland, the water 
of the German Ocean area was dammed back, and rose 
until it flowed across the neck of land joining England to 
the Continent. A lake was thus formed draining to the 
southward, which was gradually lowered by the cutting 
through of the Straits of Dover. 
