40 PROCEEDINGS OF THE SCIENTIFIC ASSOCIATION, 
where abound, probably of existing species, but in some 
instances they are of larger development than their con- 
geners of the present day. Differences of ages among the 
shells unmistakably occur too — their casts are frequent in 
the higher elevations, while others, found in lower localities, 
retain vividly their colors, thus further confirming the be- 
lief of a gradual production or growth of the island through 
separate and remote periods of elevation. The coralline 
formation superimposed on the Scotland series of chalk 
elays and sandstones, is evidently of a more recent age 
than the latter. 
The Scotland formation , one of the Tertiaries — but which 
is yet undetermined — presents a very different aspect to 
the preceding ; being a mountainous region in miniature, 
hence its name. It inclines to the Eastward in bold and 
often rugged outlines of ridge and hill with parallel valleys 
and plains intervening, while its broken and often highly 
contorted strata bearing upon their surface massive and 
scattered boulders of the coral rock disrupted from the cliffs 
_ above, attest to the suddenness and violence of the action 
from beneath b^ which it has been lifted up from the sea 
and carried with it the broken fragments from the upper 
heights of the coralline formation. The series of rocks of 
which it consists is very different from the other formation. 
Strata of chalky matter, having 94 per cent of carbonate 
of lime (the chalk) — - of siliceous sandstones of various 
hues, these alternating in some places with clay iron-stone 
— deep beds of dark and colored clays — seams of bitumi- 
nous coal ( ITanjacTc ) chiefly compose what originally was 
the bed of the sea. Iron ore, Gypsum in its crystallized 
form of selenite, pyrites, calc-tufa, and other mineral sub- 
stances are frequently found either on the surface or im- 
bedded in the strata. Several mineral springs exist, and 
