1895.] 
F. A. Shillingford —On the Kusi River. 
21 
Calcutta Bore-hole. 
larger scale on the lands flanking the Hugll, which river itself wonld 
then—as the Ganges—probably shift about into adjacent channels. 
Another interesting question now crops up from this state of affairs. 
We have all read of the celebrated Calcutta Bore-hole, a boring in 
search of pure water carried to a depth of 
481 feet, or about 460 feet below mean sea 
level, at Fort William, in 1835. At a depth of 25 feet a carbonaceous 
sandy clay was met with, which gradually passed into a bed of peat at 
30 feet, or about 10 feet below mean tide level. 1 This peat bed has 
since been found in all excavations in and around Calcutta at depths 
varying from 20 to 30 feet, and it is admitted by Geologists that there 
is little doubt that this was an ancient land surface, as wood and roots 
of the sundri tree (heritiera littoralis ) and other vegetable remains 
occur in the peat. Now it seems not unlikely that the present surface 
of the ground, in suitable localities, after such a catastrophe as above 
surmised, would present to future generations such a stratum as the 
first peat bed encountered in the Calcutta Bore-hole. It might be brought 
forward as an argument against this theory that the peat occurs at, 
or a few feet below, mean tide level, but we must remember that the 
rank vegetation from which the peat had its origin must have grown in 
soft low-lying grounds, such as the Sundri trees grow in now, and in a 
flooded state of the country the extra pressure resulting from the higher 
level of water and silt deposits, with loose semi-fluid quicksands, some 
30 feet in thickness, as encountered in the Bore-hole underlying the peat 
at no great depth, would be sufficient to settle the peat-bed a few feet 
below water level, especially as the whole country would be saturated 
with flood waters. In fact it seems probable that a general settling down 
of all the alluvial strata along the seaboard would be the natural result 
of such a condition of things. It would be extremely important and 
Old Course of the interesting to know when the main Ganges, in 
Bhagirathi. past times, last flowed through the Diamond 
Harbour Estuary. The native tradition is that the original Bhagirathi 
formerly flowed into the Estuary through the opening now occupied by 
the Rupnarain, and Fergusson 2 thinks the tradition is right, and as 
above quoted, he also considers that the main Ganges deflected into the 
Padma channel “ at some recent time.” In the map of Bengal, pub¬ 
lished in the “ Da Asia ” of the Portuguese 
historian, De Barros, during the latter half of 
De Barros’ Map. 
1 Jour. As. Soc. Beng., IX., 686 (1840), also Geology of India, R O. Oldham, 
1893, page 432. 
2 Qnar. Jour. Geo. Soc., London ; Yol. XIX., page 340. 
