348 Super fetal Gravels and Clays. [July? 
Seine, and the Thames, may have assisted in the production 
of some of the gravel-beds.* 
I am so much indebted to the suggestive papers on the 
superficial deposits, by Mr. Tylor, that I regret that I can- 
not accept his theory as satisfactory. The gravels and clays 
of the lower slopes do not differ from those of the higher 
ones, and it is not probable that rain-wash would produce 
the same effects as a flooded river. The faCt that the glacial 
deposits at Finchley remain intaCt nearly to the level of the 
present brooks shows that they have not been exposed to 
the aCtion of any extraordinary denuding agents, and floods 
and rain-wash that did not remove them could not spread 
out great sheets of gravel lower down the valley. The 
gorging of rivers by ice is doubtless a true cause of great 
floods, but water so dammed back could not reach to the 
levels we require, and would only deposit silt, and not 
spread out gravels. The theory also offers no explanation 
of the close similarity in the succession of the glacial and 
the valley deposits, nor of the resemblance of the Middle 
Glacial Sands and Gravels to the subangular gravels of the 
valleys. 
The theory that I offer in the place of these is in complete 
harmony with both the physical and the palaeontological 
evidence. It asks for no other agency than that concerned 
in the outspread of the glacial beds, and explains the simi- 
larity of those to the valley deposits by recognising in the 
latter the representatives of the glacial clays and gravels of 
the hills. It offers no opposition to the evidence of the 
comparatively short time that has elapsed since the Glacial 
period, as it admits the pre-glacial age of the southern 
valleys as well as that of the northern ones. It does not 
require us to believe that in the one case the configuration 
of the country has been completely changed, whilst in the 
other it has remained unaltered. It affords an explanation 
of the disappearance of many large animals that formerly 
abounded in Northern and Central Europe, and accounts 
for the multitude of their remains at a particular horizon. 
A new light is thrown by it on the cause of the present dis- 
tribution of animals and plants. The strongly-marked 
break that exists between the times of palaeolithic and neo- 
lithic man finds in it a solution, and the traditions of a great 
deluge a foundation. 
* Quart. Journ. Geol. Soc., vol. xxv., p. 10, and Geol. Mag., 1875, p. 437. 
