1870.] 231 



Notes on the Geology of the Vicinity of Poet Blair, Andaman- 

 Islands, — by Y. Ball, B. A., Geological Survey of India. 

 [Received 3rd March, 1870 j -read 1st June, 1870.] 



My examination of the geology of the Andamans did not extend 

 beyond the immediate neighbourhood of Port Blair. An attack 

 of fever prevented me from availing myself of the opportunities 

 which Col. M a n r Superintendent of the Andamans and Ni- 

 cobars, had kindly promised to afford me for visiting more distant 

 localities, as also from examining the excavations, which required 

 to be drained, where coal had been worked for. 



It is with some hesitation that I offer for publication these notes 

 which for the reason above stated, refer to what is but a small portion 

 of the islands, though it embraces the whole of the area in which the 

 convict settlements are situated. I do so, however, in consideration 

 of the facts that the few geological notices of these islands which 

 have been published are of a general character, and that there has 

 hitherto been no attempt to describe any stratigraphical details. 



It has been shewn by Mr. Eur z* that the principal rocks about 

 Port Blair are sandstones (tertiary). Mr. K u r z ' s specimens en- 

 abled Mr. W. T. B 1 a n f o r d to identify these rocks with those 

 forming a considerable portion of Arracan. 



The Port Blair sandstones are reported to be fossiliferousf and are 

 certainly so to the extent of containing coal. No collection of fossils 

 has been made, consequently the true position and affinities of this 

 formation to those of other countries remain as yet undetermined. J 



It is probable, however, that, as I have pointed out,§ these sand- 

 stones will prove to be of identical age with those of the southern 

 Nicobars. Dr. H o c h s t e 1 1 e r suspects the younger miocene of 

 Java to be represented by the tertiary deposits of the Nicobars, and 

 thus we arrive at the probable age of the Andaman rocks. For the 



* Report on the Vegetation of the Andaman Islands. 



f I observed in the sandstone at the N. E. end of Ross island several speci- 

 mens of a Pecten, a small Cijtherea-like shell and fragments of Oysters, which 

 fossils prove that the deposits are marine, and the aspect of these fossils is 

 undoubtedly a tertiary one. [F. Stoliczka.] 



% J. A. S. B. XXXIX, 1870, p. 27. 



§ See Records of Geological Survey of India, 1869, Part 3, p. 67. 



30 



