Murchisoris Silurian System. 21 



these deposits, since Dr. Daubeny has shewn that in many 

 of these saline sources there is an admixture of iodine, a 

 principle which is confined to the sea and its productions. 

 This argument is not, however, to be considered decisive, 

 but only as forming a portion of cumulative evidence, which 

 taken in conjunction with that of the remains occurring in 

 the deposits of this age on the continent, fortifies the con- 

 clusion, that our saliferous marls are of marine origin; for it 

 might be said, that iodine and chloride of sodium have been 

 derived in the first instance from the interior of the earth, 

 and that the ocean may have owed its saltness to beds of 

 rock-salt, as well as that rock-salt owes its origin to the 

 evaporation of sea-water." Notwithstanding the difficulty of 

 establishing the identity in remote quarters of the world, 

 of rocks so vaguely characterised as the saliferous marls, yet 

 when we have coal measures affording a certain fixed point, 

 or land mark to guide us, we cannot be very far out in fixing 

 upon the green marls, or often friable sandstone, which 

 extend along the lower ridges of many parts of the great 

 Himalayan chain, immediately adjoining the plains of Hindus- 

 tan, as the Indian equivalent of the beds in question. Along 

 the southern side of Assam we have the same rocks as well 

 as brine springs, and an earthy limestone, probably equi- 

 valent to the English Lias. On the face of the Cherra 

 mountain, the green marl rests unconformably on Old Red 

 Sandstone, (or that on which the coal formation rests), and 

 gives support to the deposits of sand in which the marine 

 remains are contained. It is here by no means destitute of 

 fossils as in other localities ; on the contrary, we found in it 

 six species of univalve shells, a small species of Echinus and 

 a large spined Cidaris. In a note which we made on the 

 characters of a fragment of rock brought away from a sub- 

 merged reef near Arracan, by the hull of a ship which 

 struck upon it, we pointed out the resemblance between its 

 appearance and that of the green conglomerates in question.* 



* Journ. Beng. As. Soc. 1838, p. 936. 



