AND GEOLOGY OF THE MALAY PENINSULA. 
125 
ation of these rivers, and the vast accumulations of alluvial matter at 
their mouths evince their undiminished energy in transporting' the de¬ 
tritus of the mountains to the sea. It is evident that the sea formerly 
covered the whole of the broad alluvial plain to the commencement of 
the mountain slopes. At that period perhaps the greatest current was 
on the western side of the Arroas, and across a tract now forming' part 
of Sumatra, and, at all events, the current of the Straits spread over an 
area more than twice the breadth of the present channel. The com¬ 
paratively feeble rivers of the Peninsula would then be aided by the 
gentler tides in filling up the hollows between the ridges and hillocks, 
and extending their alluvion seaward. But with the swifter advance 
of the opposite shore through the operation of the more powerful 
rivers of Sumatra, the tides would increase in force, oppose a resist¬ 
ance to the contraction of their banks, and turn their erosive action 
against them with the more effect the further they encroached. The 
result of tins interaction would be very different on the two hanks. 
On the Sumatra side the balance of accumulation and abrasion would 
be in favour of the land. On the side of the Peninsula it would he 
in favour of the sea. At this stage we conceive the Straits are now 
arrived. How long it lias continued, we have as yet no data on 
which even to build a surmise. 
When in Malacca for a few days in March 1846 we resided in a 
bungalow close to the beach opposite Pulo Upe. From the height 
and appearance of the alluvial plain, which is slowly wasting, we 
think it may be inferred that it is of great antiquity, that, at one 
time, it extended much further into the Strait, and that it is pro¬ 
bably many ages since its coast has ceased to advance and begun to 
retrograde. The appearance of the growing parts of the shore of 
the Strait requires that we assign a former coast line at some dis¬ 
tance seaward, and remaining stationary or advancing during a 
long period, to explain the accumulation of fine day sediment to the 
level at which it is found on the existing coast, and the after ac¬ 
cession of vegetable mould to a considerable thickness. On a sub¬ 
sequent visit to Malacca we were enabled to trace the same line of 
ancient coast, at a point further east, running inland at a slight angle 
