25 
The breccia, ironstone, and lignite were also ‘‘ natives, and to the manor 
born;” but not so the granite, quartz, and blocks of Silurian slate. 
Whence came they? Sir Charles Lyell suggested from Normandy and 
Brittany, brought hither by ice-action, when our old beach was laved 
by the Glacial sea. Nor was this at all improbable, when facts taught us 
that the eastern portion of the English Channel had subsided, since the 
great Pachyderm period, when those mammals browsed where the sea 
now rolled its waves. The whole area to the east of this, which 
had now an average depth of from 25 to 30 fathoms, was then dry 
land, while this coast-line from France to England was the highway 
along which pebbles of the paleozoic and plutonic rocks slowly tra- 
velled, till they found a resting-place in our old sea beach. 
Since the commencement of the Tertiary epoch the South Downs 
had been continually sinking beneath and rising above the waves of 
their creative mother. These oscillations were not caused by violent 
cataclysms, but by that scarcely visible process still in operation along 
our coast line. This was clearly illustrated in the Isle of Wight, the 
northern portion of which had been gradually sinking for a century 
past, and yet the sea level was the same as when Fielding 
on his voyage to Lisbon landed at Ryde a century ago, for he 
described that place as being inaccessible by sea, except at high 
water, as the tide left a vast extent of mud, too soft to bear the 
lightest weight. This mud-bank was now covered with a stratum of 
sand many feet thick, especially to the east of Ryde, which, however, 
at low water was not bare to a greater extent than was the former mud- 
bank. This clearly proved a subsidence along that part of the coast: 
and that the Solent was sinking and receiving similar deposits as did the 
Wealden Estuary, in times of old, when it sank to the depth of 1,600, 
if not 2,000 feet ! Yet, strange to say, the southern portion of the 
Garden Isle, from Duannose to St. Catherine, had, during the same 
period, been visibly rising! These facts illustrated the upheaval and 
submergence of our Downs during the Post-Pliocene epoch. 
