56 REPORT — 1851. 



fibre was fresh and tough, and could be cut v.ith an axe or saw, to which it yielded with 

 considerable difficulty. It was of a reddish colour, like that which mahogany assumes 

 when steeped in water ; in the great majority of cases it was reduced to a black, pulpy 

 state, like charcoal or the decayed timber found on our sea shores at home. This, 

 when exposed for a few weeks to the aii-, became hard and brittle, and broke with a 

 bright resinous fracture and lustre, something like that betwixt lignite and jet. When 

 exposed to damp, it in many cases became covered with a greenish-white efflorescence 

 of sulphate of iron, a substance produced in such abundance in the lignite formation 

 near Quilon that it is collected and sold as a mordant to the dyers. The tree-roots 

 referred to were everywhere perforated with holes, the work of worms or some other 

 borer; these varied from a quarter of an inch to an inch in diameter; they are almost 

 invariably lined with beautiful incrustations of carbonate of lime, from the thickness 

 of an egg-shell to that of a crown-piece ; these incrustations are composed of a mul- 

 titude of distinct layers, and form tubes of the most fantastic appearance, varying 

 from a few inches to some feet in length, but so brittle that it is seldom that more 

 than half a foot can be taken out entire. Until the present year the arrangement here 

 described was only observable in two or three localities. In consequence of the cut- 

 tings of the railway and town drain, together with the deepening of nearly all our old 

 wells and the excavation of numberless new ones, during the present season excellent 

 opportunities have presented themselves of inquiring further into the matter, and the 

 result has been that over nearly a third of the island of Bombay, or with a few excep- 

 tions, wherever the shell, gravel and concrete fyrm the material at the surface, blue 

 clay with mangrove roots, in all respects similar to those described, are found beneath. 

 Captain Fulljames appears to have found nearly the same arrangement at Gogo in 

 the Gulf of Cambay, and the same thing, so far as I can judge, is described by Capt. 

 Vicary* as visible at Kurrachee. I have in my possession the grinders and jaw-bone 

 of an elephant dug out of a well a little way above Kurrachee, from about 20 feet 

 under the surface of the ground, probably from the same formation. There are in all 

 likelihood numberless examples of the same appearances all along our coast if they 

 were inquired after. At present we only find the mangrove growing in shallow and 

 sheltered spots where mud is freely^ deposited, and we cannot expect its remains to 

 prevail over a larger area than that at present occupied by the living plant. There 

 seems to me no means whatever of explaining the appearance of the deposit of shells 

 and gravel, which from their appearance are manifestly the result of quiet aqueous 

 deposition and not of wind-drift, above tree-roots obviously iti sihi, except b}' the hy- 

 pothesis that these latter, after having obtained their present size, sunk with the soil 

 on which they grew beneath the level of the sea to such a depth as to permit the mass 

 which now covers them to accumulate. From the excavations lately made on the 

 Esplanade, Bombay, it would appear probable that the descent which gave rise to 

 this was a sudden one. In the bottom of a well 12 feet deep, just as the rock was 

 reached, coral such as that now prevailing on our shores was found in abundance; it 

 was perfectly iminjured, every pore and fibre remaining as entire as when the zoo- 

 phyte lived in it. The same species of coral now found on our .^^hores never forms a 

 rock; when it attains the size of a cubic foot or so the zoophyte dies; the coral is im- 

 mediately thereafter detached from the rock, and in a short time rounded or ground 

 to powder by the surge ; the least exposure to abrasion or impact from any hard sub- 

 stance proves fatal to the texture of a substance so delicate. The proofs of an up- 

 heaval subsequent to the subsidence are plentiful. 



It seems to me impossible to explain the production of river deltas on the usual 

 hypothesis of a deposit of silt from running water, and that mud such as that which 

 constitutes them is never thrown down except when the water which suspends it has 

 been permitted to remain for a considerable period in a state of repose. By what 

 means can it be imagined that the Deltas of the Ganges, Indus or Nile, should ever 

 be enabled to attain a level high above the reach of the highest inundations, if 

 the relative levels of land and water had at the time of their formation been as at 

 present? Assume that these rivers discharged their waters into a long shallow estuary 

 of tlie sea, the bottom of which afterwards became elevated by upheaval, and the 

 ■whole matter is simple. At Madras, from the powder-mills to Enmore, and so for 

 many miles up and down the coast, fragments of bone, oyster-shells, land and sea- 



* London Geological Transactions. 



