21 
In fact, more than one-third of the land of Europe and the 
Maltese Islands have been formed beneath the sea, and raised 
above it since the Eocene period; for London, Paris, Brussels, 
Bordeaux, Berlin, Vienna, and other towns stand upon strata 
either of Eocene or Miocene age. 
These elevations and other physical changes probably ushered 
in the great and long-continued glacial period, before, during, and 
after which an almost entire change took place in the Fauna and 
Flora, from that of the previous period. To different portions of this 
period belong the numerous remains of the large Mammalia; the 
Elephant, Rhinoceros, Hippopotamus, and other animals found in 
bone caves, freshwater deposits, and superficial gravels of this 
country and of Europe. 
Probably, the re-arrangement of this gravel, its later distri- 
bution filiing up the valleys and low grounds, may be partly due, as 
suggested by Mr. A. Tylor, to a great pluvial period, when large 
quantities of rain fell, exceeding that of Seathwaite, in Cumberland, 
or even of the Khasia Hills, in India (300 inches in a year), which 
not only strongly eroded the strata, but by the force and strength 
of the accumulated streams, excavated the valleys, carried away the 
gravels ; these were distributed over wide areas, of which evidences 
are well seen around Croydon. Situated at the junction of two 
valleys, it partly stands on beds of gravel (containing elephant 
remains), composed of rounded and unrounded flints, belonging to 
different periods. It extends widely over the valley of the 
Thames, and has been itself scooped out. The portions of 
Bagshot sands previously noticed now remaining attest the 
amount of denudation to which the area has been subjected.* 
Such is briefly the evidence derived from the study of the strata 
found around Croydon; they are not: isolated portions simply 
deposited at one time and in this locality ; but fragments of strata 
which haye been formed over very large areas, and under 
very different conditions. First, the warm Cretaceous period 
and the subsequent break; the erosion of the chalk and 
deposition of the marine Thanet sands, with a milder climate. 
The estuarine Woolwich beds, the erosion of a chalk cliff, and the 
formation and dispersion of the Oldhaven and basement beds, with 
their marine Fauna, the depression and change which brought in the 
* Dr. Forbes Watson in noticing Indian rainfall, says ‘‘A striking ‘example of the 
influence of the latter being found in the Khasia Hills in which, during five days, a 
down-pour of 30 inches in each successive periods of 24 hours was measured by Dr. 
Hooker, and in which the yearly rainfall frequently exceeds 600 inches. In such a 
country all the phenomena of the denudation and erosion of mountains, hills, and table 
lands, of the formation of alluvial plains, and the growth of deltas, take place with a 
rapidity and on a scale of magnitude elsewhere unexampled. The study of all these 
processes is important alike to geography and geology, as showing in actual operation 
those very forces, to the long-continued action of which must be ascribed most of the 
geological changes.”—On the Establishment of an Indian Institute, dc. London, 1875. 
See also Mr. Whitaker “On River Drifts,” in the Guide to the Geology of London, 
1875, p. 60.—A. Tylor, Geol. Mag., Sept., 1875, p. 459. 
