1825.1] 
gentlemen’s researches in the first in- 
stance. 
After passing through the Alluvium 
or vegetable soil (which covers the 
greater part of the surface of the central 
and south-east division of the kingdom), 
we find in many situations beds of 
rounded pebbles, commonly mixed 
with loam or sand, of various degrees 
of thickness: which beds are sup- 
posed to have derived their origin 
from the attrition produced by the 
waters of the deluge; these masses of 
gravel are, however, more prevalent in 
the midland counties (frédm the debries 
of the elder rocks), than in those of the 
south and south-east. 
The Isle of Wight presents, to all ap- 
pearance, the most recent deposite of 
regular strata in the whole kingdom ; 
and (as far as researches have yet gone), 
probably, in the whole surface of the 
globe. On the north side of the island, 
the face of the cliff at Heedon Hill ex- 
hibits, beneath the alluvial soil of the 
surface, a bed of calcareous stone, about 
fifty-five feet thick, containing a variety 
of shells, the species of which are, at 
present, known to exist only in lakes 
or fresh-water rivers. Hence this for- 
mation has been referred, by Mr. Web- 
ster and others, to the deposit or 
growth of the stratum by the accumu- 
lation of these testaceous animals at 
the bottom of some river or lake, There 
exists the strongest internal evidence 
that these beds of shells must have been 
generated in the spot they now occupy ; 
for the delicate structure of the shells, 
and their perfect state of preservation, 
in many parts of the mass, totally pre- 
cludes the idea of their having under- 
gone much friction. 
Immediately subjacent to this follows 
a stratum of thirty-six feet thickness, 
the substance of which approaches very 
near to the character of the crag-rock 
on the coast of Suffolk and Norfolk, 
and contains large masses of fossil 
oysters, and other shell-fish of marine 
origin. 
Next to this marine deposite, is a series 
of beds of sand, marle, and calcareous 
rock, interspersed with argillaceous and 
coally matter. The organic remains in 
these strata, though less considerable 
in quantity, are of greater variety than in 
the superior beds. The thickness of 
this lower fresh-water deposite is about 
sixty feet, at Headon Hill; but it ap- 
pears to be much thinner in Binstead 
quarries, and other parts on the north- 
east side of the island, where it has 
Geology of the Isle of Wight. 
205 
been dug for the purpose of the builder. 
The mansion of Lord H. Seymour, Mr, 
Nash, and other good houses in the 
vicinity of Cowes, are of this calcareous 
stone. Below this stratum, at the foot 
of Headon Hill, succeeds a layer cf 
fine white and yellow sand, ex- 
tending to an unknown depth, being 
covered by shingle. This sand has 
been largely employed for making glass. 
The next stratum, in the series be- 
low the aforementioned beds, is the 
reat argillaceous deposite that fills the 
whole of what is termed the “ chalk 
basin,” in which stands the metropolis, 
the whole of Middlesex, and part of the 
adjacent counties: hence called the 
London clay formation. 
This great stratum varies consider- 
ably in thickness in the neighbourhood 
of the metropolis. According to Mr. 
Phillips, from 77 to 700 feet thick. 
“ The position of the beds of this clay 
is so nearly horizontal, that no perceptible 
difference from that position has been ob- 
served, except in the Isle itself, where this bed 
is nearly vertical.” — Outlines of Geology. 
The vertical section of the blue clay 
here alluded to, forms the hollow in 
the cliffs between the north end of 
Allum Bay and Headon Hill, where it 
measures about 250 feet in width. From 
Allum Bay, the clay proceeds, in a nar~ 
row belt, through the interior of the 
island, near Newport, and emerges at 
White Cliff Bay, on the eastern extre- 
mity, following a course very nearly 
east and. west. 
Beneath the bed of ke1e, or London, 
clay, lie a series of beds of sand, marle 
and coloured clays, denominated, by 
Mr. Conybeere, the “ Plastie Clay For- 
mation ;” from the porcelain clays be- 
ing included in this series, These beds 
which, like the blue clay, lie nearly 
horizontal, in the London basin, have 
been thrown into a vertical position in 
the Isle of Wight, where they form a 
very beautiful and conspicuous object 
in the face of the cliffs at Allum Bay; 
extending upwards of 1,100 feet along 
the shore. When any portion of the 
surface has been recently broken off, 
the sands exhibit a whole range of 
prismatic stratum, more especially when 
illuminated by the rays of the set- 
ting sun. It is, however, remarkable, 
that although this series of plastic 
clay and sand-beds, follow the order of 
the blue clay formation, to which it is 
subjacent, in passing from east to west 
through the island; yet the whole 
has not been subject to the convul-,, 
sion.) 
