9G 
SKETCH OE THE PHYSICAL GEOGRAPHY 
no real plane of division. A much lower level must be sought as 
the true geological basis of Asia. To determine the depth and boun¬ 
daries of this basis, and to distinguish its original limit from that 
which it acquired in after periods, are problems perhaps beyond even 
the science of future generations, involving as they do not only facts 
bidden from all our existing methods of observation, but, in all pro¬ 
bability, a series of changes of such a sort that the newer have tend¬ 
ed to obliterate the vestiges of the older. But that this basis extends 
far to the southward of the mass of the continent is demonstrable. 
In the chain of evidence the Malay Peninsula forms an [important 
link. It is directly united not only geographically but geologically 
with the continental mass, and, through the islands to the south and 
Sumatra on the west, a connection with the rest of the Malayan Ar¬ 
chipelago can be established. 
We have seen that the Peninsula may be considered, when divest¬ 
ed of its alluvial fringes, as one continuous belt of mountains and 
hills separating from the Hindu-Chinese region in latitude 13° 30’ 
N. When we extend our observations to this region we are enabled 
in some measure to understand the law of its origen. At least cer¬ 
tain connections are at once apparent which point directly to such a 
law. We find that the broad tract, stretching to the eastward over 
Siam, Kamboja and Cochin China, with which the Peninsular zone is 
amalgamated, is not an uniform elevated continental mass, in which 
the Peninsula merges, as the Straits of Malacca lapse in the sea of 
Bengal. On the contrary, we find that the Peninsular zone of ele¬ 
vation continues uninterruptedly, the only change being that its west¬ 
ern border becomes a broad fiat sheet of alluvium instead of water, 
and that beyond this alluvial region another elevated zone occurs, 
succeeded by a second tract of alluvium, which again is bounded by 
a third elevated belt. How far to the north these great alluvial 
plains extend, and how much the northern limit of the Malay Penin¬ 
sula has been pushed south by the gradual filling up of the north¬ 
ern part of the Gulf of Siam, we have no authentic knowledge. 
Looking to the size of the Menam, and Mekon or Kamboja river at 
their mouths, and the great length of their courses, we are prepared 
