360 Remarks on the Geology of Tavoy. 



which seems to be its continuation down the coast is a dif- 

 ferent formation ; being wholly composed where I have crossed 

 it, of gneiss, with red sandstone on its western side near the 

 base. That this is the old red is probable from other consi- 

 derations besides its relative position, for where the range 

 is continued down within the limits of Mergui, its summit in 

 one location is said to be covered with tracks of various ani- 

 mals in the rock,* and " similar forms," says Mr. Murchison, 

 " are found in numberless portions of the old red sandstone, 

 imitating in their outline horse-shoes, rings, almonds, &c." 



In the intervening valley are seen several different strata of 

 slate rocks, and occasionally isolated masses of mural lime- 

 stone, rising in one instance at least several hundred feet 

 high, and abounding in cylindrical pits of a few feet in diame- 

 ter, but of an unknown depth ; resembling wells sunk in the 

 rocks by art. They probably correspond to the cavities exist- 

 ing in the limestone of Wales, which Murchison says, " taper 

 downwards to depths of 30 or 40 feet, and apparently termi- 

 nate in vertical tubes. As they occur at or near points of the 

 greatest dislocation of the strata, may we not be allowed to 

 speculate upon their having formerly been the spiracles by 

 which certain gases were evolved, during those periods when 

 earthquakes produced the adjoining elevations and depres- 

 sions of the strata." Tin is found at different points through- 

 out the whole length of this valley, but usually on its eastern 

 border, and in no great quantities ; though I have seen traces 

 of former works one or two days travel above Kaleoung, as 

 well as on Talaing-yurva river, some twenty miles north of 

 Tavoy, and the natives say it is found at Young-byouk, and 

 at the head waters of Palouk river, which is within the juris- 



* These marks are produced probably by decomposition and weather- 

 ing of the surface. The conjecture regarding the nature of the rock is 

 probably correct. Its relative position on the one side to primitive 

 rocks, and on the other to slate clay containing impressions of coal 

 plants are in favour of the accuracy of the author's view. — Ed. 



