O? THE TENASSERIM PROVINCES. 387 
containing a large proportion of hornblende. These blocks 
correspond in their general features with similar masses 
found on the main shore. 
The direction of the ranges of the insular hills is parallel 
to that of the hill ranges on the main land, nearly N. and 
S. ; and the stratified rocks observe the same angle of dip 
and conformity of position as their congeners on the shore 
where littoral sections are found;—it may thence be con¬ 
cluded, that the same subterranean forces which erected the 
chain of mountains dividing the Peninsula, must have operated 
at the same period to produce the hid ranges of the Islands* 
Connected with this subject it has been remarked, that granite 
which forms the prominent feature in the formation of the 
Islands, with an altitude, as in the instance of Double Island, 
of only 97 feet, is said to be rarely found either in the me¬ 
diate or main ranges of the Coast which approach to the 
height in some instances of 5,000 feet. 
Various speculations have been entertained and as many 
theories advanced on the subject of laterite formations; the 
fact however of their being found more generally in conjunc¬ 
tion with rocks of the primary order, and superimposed on 
granite or gneiss, affords a basis upon which to ground 
a system of observation that may tend to elucidate the 
subject, and as this Coast offers peculiar facilities for such 
observation, from the general prevalence of the rock in 
question, I shall here state the result of a series of observa¬ 
tions, which have been prosecuted to that end. 
The minute examination of the rock specimens from the 
Islands with which the laterite is associated, as well as those 
from the main shore, exhibits a slightly varying relation to 
to each other in their unstratified granitic character, less so 
however in the gneiss where the mica and hornblende occut 
in the same lamina ; in the former, especially in that forming 
veins in the schistose rocks, the hornblende and felspar 
predominate. Such in fact may be said to be the character of 
the whole of the granitic masses found on the Islands, with 
the exception of those disseminated masses in which the pre¬ 
sence of quartz, in large aggregated crystals, gives the rock a 
decidedly porphyritic character. This is the principal form 
of igneous rock of which Double Island -is composed, the 
ingredient , being quartz in laminae forming cuboHal masses 
with glassy felspar and hornblende, both large grained ^and 
irregular, hence it may be termed a sienitic porphyry. The 
atmospheric action upon both hornblende and felspar, 
owing to the large portion of oxide of iron in the for- 
