Octop.er 1 1 1887.] THE TROPICAL AGRICULTURIST. 285 
distance*; and perhaps, as already hinted, the cal- 
careous matter is washed out in process of long time 
by the action of the heavy periodical rains. 
It will be Been that Davy referred the origin 
of the siliceous soil superimposed on the lime- 
stone base, to wind instead of water currents. 
As there is an interval of only 40 miles between 
Point Calimore on the Coromandel Coast and 
Point Pedro in Cey.on, and as the wind currents 
in the north-east monsoon are exceedingly power- 
ful, aerial currents may certainly have done 
their part in supplying Jaffna with soil. — Dr. 
George Gardner was able t > personally visit 
Jaffna : he wrote in 1847, about a third of a 
contury alter Davy had recorded the facts and 
opinions we have quoted, and this is what he 
said of the geology of the Peninsula: — 
Passing over all thoso series of rocks to which the 
nameB of secondary and tortiary haye been given, 
none of winch aro known to exist in Ceylon, _ we 
come to those very modern ones callod post tertiary, 
which are being formed at the present day, and which 
either shew themselves in the shape of elevated ter- 
races of shells, or in a more solid form arising from 
the agglutination of particles of sand and fragments 
of such coralinos and Bhells as still inhabit tbe sur- 
rounding seas. Such elevated shell banks, and such 
rocks are to bo 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 
thoir existence at Gallo and at Belligam. The study 
of these modern formations is of peculiar interest 
to tho Geologist, as they aro fraught with important 
analogies as to tho process of nature in more ancient 
timos. At Jaffna the lower portions of this breccial 
rock is qu.rried for bui ding pu poses. It in com- 
pact in its structure, but abounds in very perfect re- 
mains of Bhells and corals, and in its general struc- 
ture resembles very much • h<j same kind of rock in 
which human reuiHins have b« en found on the north- 
east coast of tho main land of Guadaloupe. Along 
the shores of the lagoon which separates the main 
laud from the peuinsula of Jaffna, and but little ele- 
vated above tho present pea level, the formation of 
this rock may be Been in vauons states of progress 
towards Bolidi deal ion. Sonic specimens which I col- 
lected there consist of nearly an entire rmtss of small 
shells similar to those which are still found abun- 
dantly alive within tlio present tidal r nge, and aro 
In ut i in I examples of tho manner in which those 
lime-stono rockB of the secondary strata which are 
BO full of the rema ns of shells and other marine 
animalB. have been formed. 
Finally we quote from tbe work of Sir EmertOD 
Tennent :— 
The laud bas for ages been slowly rising from the 
sea, and terraces abounding in marine shells imbed- 
ded in agglutinated sand occur in situations lur above 
high-water murk. Ini'iiedintcly iuluud from P iut de 
Qalle, the surface soil resU on a stratum 01 decom- 
posing coral ; and s a shells are found at a consider- 
able distance from tho shore. Further north at 
Madiimpe, between Chilaw and Negombo, the shells 
of pearl oysters and other bivalves are turned up by 
the plough more tlim ten miles from tho sea. 
These recent formations present themselves in a still 
more striking form in the north of the island, the 
greater poition ol which may bo regarded as tbe 
conjoint production of the coral pohpt, and the cur- 
rents, winch tor the greater portion of the year set 
impetuously towards I he south. (Joining laden with 
alluvial matter collected along tho coast ol'Ooronian- 
del, and meeting with obstacles south of Point Oali- 
mere, they have deposited their burthens on the coral 
reefs round Point Pedro ; and these gradually raised 
• There are very many instances of sand being 
carried to n great distance by the wind. On our voyage 
from India, approaching Table Bay, at the OejM of 
Good Hope, the 8. K. wind blowing stroujrly off laud, 
wan no improgiiNted with ■ lubtle nan J, like that of 
Dolft, that it proved very troublesome, oven three and 
four ailes olf the ibore. 
above the sea-level, ond covered deeply by sand drifts, 
hove formed the peninsula of Jaffna and the plains 
that trend westward till they UDite with the narrow 
causeway of Adam's Bridge — itself raised by the same 
agencies, and annually added to by the influences of 
the tides and monsoons. (*) 
On the north-west side of the island, where tha 
currents are ohecked by the obstruction of Adam's 
Bridge, and still water prevails in the Gulf of Manaar, 
these deposits have profusely heaped, and tho low 
sandy plains have been proportionally extended ; 
whilst on tho south and east, where the current 
sweeps unimpeded along the coast, the line of the 
shore is bold and occasionally rocky. 
NoRTHBRN Province. — Coral Formation. — But the 
principal scene of the most recent formations is the 
extreme north of the island, with the adjoining pen- 
insula of Jaffna. Here the coral rocks abound far 
above high-water mark, and extend across the island 
where tho 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 surfaco, 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 Manaar. 
The phenomenon of tho 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, betweon the 
island of Manaar and Karativoe, the natives, in ad- 
dition to fishing for chank shells f in the sea, dig 
them up in large quantities from beneath the soil 
on the adjacent shores, in which they are deeply 
imbedded, j 
The sand, which covers a vast extent of tho pen- 
insula of Jaffna, and in which the coconut and 
palmyra-palm grow freoly, has beon carried by the 
currents from the coast of India, and either flung 
upon tho northern beach in the winter mouths, or 
driven into the lake during the south west monsoon, 
and thence washed on shore by the ripple, and dis- 
tributed 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 pro- 
duces crop? of great luxuriance. This tillage is 
curried on exclusively by irrigation from innumer- 
able 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 msko their way under-ground, and 
rise thorough the sands on the margin of the sea 
at low water. 
Tennent ta ks of the subterranean water rising 
fresh through the coral, but we submit that 
much of the good effect of the numerous irrig- 
ation wells by means of which tho J&ffna Peninsula 
is cultivated like a garden, is due to tho fertilii- 
• The barrier known as Adam's Bridge, which ob- 
structs the navigation of the channel betweeu Ceylon and 
Kainuad, cousisis of severs I parallel ledges of conglo- 
merate and sandstone, hard at the surface, and grow- 
ing coarso and soft as it descends till it rests ou a 
bank of sand, apparently accumulated by the influence 
of tno currents at the change of the monsoons. See 
an Fluty by Captain Steuart on the Paumben Pastagt, 
Colombo, 1837. Heo Vol. II. p. 664 
f y»rfc>W/« mpa, formerly known as Valuta gravit, 
used by the people of India to bo sawn into bangles 
and anklets. 
J In 18-10 an antique iron anchor was found nuder 
the soil nt tho north wi .tern point of Jaffna, of such 
sizo and weights us to show that it must have be- 
longed to a ship of much greater tonnage than any 
which the depth of water would permit to navigate 
the channel at (hs pre««n< day. 
