DISRUPTION OP THE STRATA. 
351 
terially changed the physical geography of the 
south-east of England, and the contiguous parts of 
the continent, and occasioned the vertical position 
of the strata in the Isle of Wight and Hampshire.* 
These alterations in the suidace of the country, 
must, too, have been attended with great changes 
in the hydrograjihy of Hampshire, Surrey, Kent, 
and Sussex ; the waters residting from the drainage 
of the land, and which, before tlie existence of the 
transverse fractures, jirobably flowed through the 
longitudinal valleys towards the east, would be 
thrown into different channels, and find their way to 
tlie ocean by the existing river courses, t Traces of 
these revolutions remain in the boulders and su- 
jierficial loam and gravel, which occupy the valleys 
and low elevations of the south-east of England. 
Subsequently to these last-mentioned changes 
the surface of tlie country appears to have under- 
♦ In other parts of Europe we have also proofs of great vicissitudes 
of land and sea, and oscillations of level since the commencement of 
the tertiary period, and that earthquakes have taken place by which 
the land has not only been lifted from above the waters, but to an ele- 
vation of several thousand feet above the level of the sea. Thus the 
Alps have acquired an additional altitude of from 2000 to 4000 feet ; 
and the Apennines owe a great part of their height, from 1000 to 2000 
feet, to subterranean convulsions which have happened within the 
same epoch. Vide Principles of Geology, vol. ii. p. 308. In Mr. Bake- 
well’s Travels in the Tarentaise, and various Parts of the Grecian and 
Perinine Alps (2 vols. 8vo. Longman and Co. 1823), the reader 
will find many highly interesting remarks on the physical structure of 
the Alps, and the elevatory movements which they have sustained ; as 
well as on the extinct volcanoes of central France. The Pyrenees 
have accjuired the whole of their present altitude, which in Mount 
Perdu exceeds 11,000 feet, since the origin of some of the newest 
members of our secondary formations. 
f The Cliff Hills, near Lewes, afibrd an interesting example of the 
manner in which a large proportion of the chalk valleys have been 
