met
with in several places along the coast. Thus the greater part of the
Peninsula of Jaffna is formed of them, and I have likewise noticed
their existenee at Galle and at Belligam. The study of these modern
formations are of peculiar interest to the geologist, as they are
fraught with important analogies as to the process of nature in more
ancient times. At Jaffna the lower portions of this breccial rock is
quarried for building purposes. It is compact in its structure, but
abounds in very perfect remains of shells and corals, and in its
general structure resembles very much the same kind of rock in which
human remains have been found on the northeast coast of the main land
of Guadaloupe. Along the shores of the lagoon which separates the main
land from the peninsula of Jaffna, and but little elevated above the
present sea level, the formation of this rock may be seen in various
stales of progress towards solidification. Some specimens which I
collected there consist of nearly an entire mass of small shells
similar to those which are still found abundantly alive within the
present tidal range, and are beautiful examples of the manner in which
those limestone rocks of the secondary strata which so full of the
remains of shells and other marine animals, have been formed. At Galle
a somewhat similxr kind of rock is used for building purposes, but the
shells and corallines of which it is composed are more comminuted. At
one of the places where this rock is worked, situated about a mile from
the sea, and about six or eight feet above its present level, I found
firmly attached to those portions of it which were exposed by the
removal of the alluvial soil which covered them, numerous oyster
shells, exactly similar to those now found alive on rocks at present
washed by the waves of the ocean. At Belligam a large tract of alluvial
land, which at the time I visited that place, in 1844, was planted with
sugar cane, is underlaid by a thick stratum of sea shells and fragments
of corallines, which are more or less firmly agglutinated together; and
I have no doubt that many other parts of the coast offer similar
phenomena.
The
existence of these masses of shells above the present level of the sea,
yields the same evidence of the gradual rise of the island of Ceylon,
that is afforded by similar appearances in other parts of the world,
and from which similar conclusions have been drawn by the moot eminent
geologists of the day. In many places where such rises are slowly but
surely going on, the rate is so imperceptible that but little change
has been observed during* the historical period; where as in others,
such as the Scandinavian peninsula, the rise is as much as three feet
in the course of a century. From all that I have seen I am led to
believe that the whole of that flat sandy country which stretches along
the west coast of Ceylon, as well as that of a similar nature at
Batticaloa, which, except Trincomalee which is rocky, is the only part
of the east coast that I have yet visited, has, at no very recent
geological epoch been gained from the sea by the elevation of the land.
The
conclusions to be deduced from the above slight sketch of the Geology
of the Island are very evident. In the first place, the non-existence
of secondary and tertiary rocks overlying the Gneiss and Dolomite,
prove that from the period of the first elevation of Ceylon above the
level of the ocean, it has not been subjected to the numerous
submersions and upheavals which, it is well ascertained, such countries
as possess them have been liable to; indeed, there is no evidence to
prove that it has even once been covered with water since the time at
which it first became dry land, for nearly the whole of the soil which
covers it, with the exception of the sandy portions along the coast,
and a very thin layer of alluvial matter has been formed from the decay
of the gneiss rocks. Nowhere have I met with traces of diluvial drift,
except, indeed, where it can be traced to the action of streams. In the
second place, the gradual rise of the whole island may be fairly
inferred from the existence of the elevated beaches which I have
alluded to, and I have no doubt that when further attention has been
given to the subject by those who have opportunities for so doing,
still more satisfactory evidence of the fact will be afforded.
