PART 3.] 
Hochsteller, Geology of Nicobars. 
65 
Pulo.Milu was particularly instructive for me, because the dependence of the vegetation 
on the soil and its geological basis could be perfectly well recognised. The vegetation and 
the geological formation of the ground stand in the closest relation to each other, as clearly 
shown by the accompanying sketch plan. The sandstone hills are covered with jungle ; the 
coral (calcareous) ground with high forest trees; the saline, calcareous, sandy ground is occu¬ 
pied by cocoa-palms, and in the fresh water swamp on the declivity of the hill range, which 
resembles in its curve a horse shoe, thrives the finest forest of Pandams which we have seen 
on the Nicobar Islands.—PI. 4, Pig. 5. Plan of the island of Pulo Milu. 1, Sandstone 
with bushy forest; 2, Coral conglomerate, with high tree forest; 3, Coral and shell sand, with 
forest of cocoa-nut trees ; 4, Coast reefs ; 5, Presh water alluvium, with forest of Pandanus. 
PI. 4. Pig. 6, Section of same island on line A. B. Fig. 5. 
We have not visited the coast of Little Nicobar, the mountains of which rise to 1,000 
feet elevation above the sea. 
Kondul —between Little and Great Nicobar,—consists of a billy ridge, 11 nautical 
miles long and f mile broad; its strata strike north-north-west., and dip at 70^towards east. 
The western side is the precipitous one. The strata represent an alternation of more or less 
sandy or clayey beds. The sandstone predominates, yellowish-white, with ferruginous 
reddish-brown particles. The clayey beds partly consist of a greasy plastic clay, partly of a 
crumbling yellowish clay marl, with intercalated thin-bedded sandy slates. The' only organic 
remains which I found were indistinct traces of Alga and small rolled fragments of'coal. 
Great JXicohar . What shall I report of Great Nicobar? With the exception of 
some sandstone hills on the northern coast, and the sandstone ranges on the eastern side of the 
Galathea Bay in the south, I have not seen anything. Great Nicobar, with its moun¬ 
tains rising up to 2,000 feet, is geologically quite a terra incognita. 
A very remarkable earthquake, which is said to have lasted from the 31st of October to 
the 5th December, 1847, on the Nicobar Islands, at which time also earthquakes occurred in 
the middle and western part of Java, is described from the Penang Gazette in Junghuhn’s 
Java (part II, p. 940). On this occasion fire is said to have been seen on one of the 
mountains of Great Nicobar. 
Can the highest mountain of Great, Nicohar he a volcano P Its form is that of a volcano, 
hut as Jungliuhn says that one could land on the southern coast of J ava, wander about many 
days among sandstone and slate rocks, without obtaining through any of the phenomena 
even a trace of the stupendous volcanic nature of Java; in the same way there may be in 
the interior of Great Nicobar, rock-formations hidden, of which one does not got an idea 
along the coast. However, I do not attach any importance to the nunour that fire has been 
seen on Great Nicobar, though the description of the earthquake seems trustworthy, 
as I had myself occasion to observe on Kondul the mountain-slips referred to in the account! 
These few observations, Combined with those of Dr. Kink, give us the following thouc-h 
probably still very imperfect, idea of the geological nature of the Nicobar Islands. 
Among the various geological formations on the Nicobar Islands, three are the most 
important1, An eruptive serpentine and gabbro formation ; 2, Marine deposits, probably 
of a younger tertiary age , consisting of sandstone, slates, clay marls and plastic clay 3, 
Bevent coral reef formations. 
The serpentine .and gabbro formation of the Nicobars is characteristically of an erup- 
Lve nature. The tertiary sandstones, slates and clay-marls appear forcibly broken through; 
“eir strata are partly inclined, partly bent in flat, parallel, wave-like, undulations. These 
rocks are accompanied by coarser and finer breccias composed of angular fragments of these 
same rocks, and they can partly he regarded as friction-breccias, partly as sedimentary 
Intas m which beds of an argillaceous marl are interstratified. The eruption of these plutonio 
masses appears, therefore, to tall in a time when the formation of the marine deposits was 
partially completed, partially still in progress. They broke through, on lines of fracture of which 
the principal strike from south-south-east to north-north-west agrees with the longitudinal ex- 
tension of the islands. On the middle islands, the serpentine and gabbro attain their greatest 
development; on Tillangchong, Terressa, Bompoka, Oamorta and Nancowry they 
lorm bare hill-ranges of from 2,500 feet elevation, and their configuration often marvellously 
