258 Geology of the Neilyherries. [No. 12, new series. 



valley streams progress towards their confluences, large rivers in 

 the low country, the constant action of the running waters under- 

 mines the rocky sides of their channels, and the banks in the 

 sequel give way and fall into the current. The comminuted de- 

 bris of the syenite rocks of the Neilgherries, in the shape of sand 

 carried into the ocean, bears along with it bones and remains of 

 animals now existing, both terrestrial and fluvial ; and in after 

 ages some future geologist will perhaps examine petrified fishes, 

 and other marine animals, along with fresh water shells, vegeta- 

 bles, and perhaps the remains of his fellow-man, in an indurated 

 sand-stone formation, now in progress at the bottom of the ocean, 

 which once composed the materials of the Neilgherry Hills : that 

 is, supposing the ocean bed shall have been upheaved while the 

 present continents subsided, in completion of another of those 

 oscillatory movements that have wrought so many changes in the 

 face of our planet, but on a scale of greater magnitude, and in a 

 space of longer duration than that I have previously alluded to. 



The last deluge that visited the Neilgherries has left behind 

 it a thin stratum of gravel, now occupying a position between the 

 vegetable soil and the surface of the clay below it. This gravel 

 has been confounded by some with the decomposing surface of the 

 older rocks. The same flood likewise excavated in the action of 

 its eddies, many of those hollows seen in the sides of the Hills. 



Subterranean springs undermining superstrata, have produced 

 instances of the geological phenomena known as " Landslips," 

 the most conspicuous being the well known avalanche. The 

 same element has contributed to wear down precipices by remov- 

 ing the entire fagade, which in its descent has highly polish- 

 ed the parent mass behind it. In one instance I have observed 

 the fagade leaning against the base of the rock from the face of 

 which it has slid. 



Atmospheric agency has largely contributed to wear down the 

 surface of the Neilgherries. The shape of many of the low round- 

 ed hills is referable to it, the syenite having exfoliated in con- 

 centric layers from their summits. In the course of my examina- 

 tions of the effects of decomposition upon rocks in this locality, I 



