28 



Brief note* on the Geology SfC. of Nancowry harbour. [No. 1, 



in Nancowry haven, on the Camorta and Nancowry shores. At the 

 western entrance, there are great beds of conglomerate, some al- 

 most vertical, striking N. W.— S. E. 



3rd. — Gabbro and Serpentinous rocks, well seen on the highlands 

 east and west of the village of Alta Koang on Nancowry. 



The coral rocks together with the sea drift form the soil in which 

 the cocoa-nuts and vegetables cultivated by the natives grow and 

 thrive. 



The magnesian claystones, on disentegration, form a soil incapa- 

 ble of supporting more than a crop of grass. In the valleys where 

 this formation occurs, the accumulating of vegetable matter &c. 

 brought down by the streams, has proved sufficient in many cases 

 to support a jungle of large trees. But in the hot house climate of 

 the Nicobars, the poverty of the soil is so great, that the tops of 

 some of the hills are perfectly bare, or are only able to support a 

 fern, Gleichenia dichotoma. The presence of a conglomerate bed 

 has the effect, by the decomposition of its contained pebbles of 

 igneous rocks, of locally improving the character of the soil. 



The igneous rocks, Gabbro and Diorites, produce a much better 

 soil which is capable of supporting a dense jungle. 



To the variability in the fertility of the soil which is thus ex- 

 plained is due the peculiarity of the scenery at Nancowry. 



In the southern Nicobars, according to all accounts, and certainly 

 in the Andamans, the greater uniformity is due to less variability 

 in the character of the soils, derived from the rocks forming those 

 islands. 



As to the economic resources of the rocks, they cannot be esti- 

 mated at a high rate. The coal of the southern islands is evident- 

 ly similar to that of the Andamans, being simply derived from 

 fragments of drift wood and forming little strings and nests in the 

 sandstones in which it is imbedded. Dr. Rink discusses the pos" 

 sibility of gold being found in the igneous rocks. No trace of it has, 

 however, been found. It is extremely improbable that the Nicoba- 

 rians know its value. 



Both Dr. E i n k and Dr. Hochstetter obtained small traces 

 of copper in the igneous rocks. This fact could not, however, be 

 used as a proof of its occurrence in large quantities, though it might 

 justify a closer and more extended examination of the locality. 



