" Northern Province.—Coral Formation.—But the principal scene of the most
recent formations is the extreme north of the island, with the
adjoining peninsula of Jaffna. Here the coral rocks abound far above
high-water mark, and extend across the island where the land has been
gradually upraised from the eastern to the western shore. The
fortifications of Jaffna were built by the Dutch, from blocks of
breccia quarried far from the sea, and still exhibit, in their worn
surface, the outline of the shells and corallines of which they mainly
consist. The roads, in the absence of more solid substances, are
metalled with the same material; as the only other rock which occurs is
a description of loose conglomerate, similar to that at Adam's Bridge
and Mannar.
"
The phenomenon of the gradual upheaval of these strata is sufficiently
attested by the position in which they appear, and their altitude above
high-water mark; but, in close contiguity with them, an equally
striking evidence presents itself in the fact that, at various points
of the western coast, between the island of Manaar and Karativoe, the
natives, in addition to fishing for chank shells* in the sea, dig them
up in large quantities from beneath the soil on the adjacent shores, in
which they are deeply imbedded.f
"
The sand, which covers a vast extent of the peninsula of Jaffna, and in
which the coconut and palmyra-palm grow freely, has been carried by the
currents from the coast of India, and either flung upon the northern
beach in the winter months, or driven into the lake during the
south-west monsoon, and thence washed on shore by the ripple, and
distributed by the wind.
"
The arable soil of Jaffna is generally of a deep red colour, from
admixture of iron, and, being largely composed of lime from the
comminuted coral, it is susceptible of the highest cultivation, and
produces crops of great luxuriance. This tillage is carried on
exclusively by irrigation from innumerable wells, into which the water
rises fresh through the madrepore and sand; there being no streams in
the districts, unless those percolations can be so called which make
their way under-ground, and rise through the sands on the margin of the
sea at low water."
Tennent
talks of the subterranean water rising fresh through the coral, but we
submit that much of the good effect of the numerous irrigation wells by
means of which the Jaffna Peninsula is cultivated like a garden, is due
to the fertilizing salts of lime brought up in the ola baskets with the
irrigation water.—We trust the information we have thus brought
together may be useful to our correspondent and others, but a regular
scientific survey of and report on our rocks and minerals is a
desideratum still to be supplied. For instance, the received opinion
is^ founded on the fact that there are no lakes amongst the mountains
of Ceylon that none ever existed. We hold strongly, contra, that the
Plain of Nuwara Eliya is the bed of an ancient lake whence, when the
barriers were worn away or broken up, the waters escaped into Uva on
the eastern side; into Dimbula on the western. There are other similar
localities amidst our mountains, and the valley of Maturata is so
narrow and its sides so steep that it resembles the formations called
canyons, down which rivers tumble over sheer precipices into the
Yosemite valley in California. We cannot help thinking that captured
water, long retained but finally breaking the barriers which confined
it, has had something to do with this formation and similar ones in our
Ceylon mountain system.
While
we are writing a specimen of rock is brought to us taken at a depth of
70 feet, from the borings which are going on at Mannar, with the hope
of finding a perennial supply of water at that truly penal station,
where, what
* Tarbindla rapa, formerly known as Valuta gravis, used by the people of India to be sawn into bangles ant anklets.
t
In 1845 an antique iron anchor was fouud under the soil at the
north-western paint of Jaffna, of such size aud weights as to show that
it must have belonged to a ship of much greater tonnage than any which
the depth of water would permit to navigate the channel at the present
day.
