Dec. 1861.] Geology of the Neilgherries. 235 



through it, and against the Syenite imparting to the latter a 

 Schistose character. 



Taking a general view of the subject, I also conceive the chasms 

 and fissures opened in the crust of the earth, were the ducts 

 through which the waters that at different periods deluged it, 

 found their way to the surface. 



It is not impossible, either, that the Siliceous Schist owes its 

 origin to contemporaneous circumstances, being a sediment from 

 the muddy waters that passed through the fissure near the conclu- 

 sion of a cataclyson. 



Further examinations of these Rocks have confirmed the 

 idea of the Trap being more recent than the vein of Schist. 



It may be seen traversing the latter in various directions, con- 

 torting it in a most remarkable manner. In some sections the 

 Trap has the contour of a wedge, confessing it has inserted itself 

 into a fissure. 



Latterly renewing my researches along the ridge below 

 Snowdon,I found the same Trap vein that intersects the Siliceous 

 Schist, bursting through the sequestered bank of one of the horse 

 shoe hollows met with in the acclivity of the ridge. 



Instead of compact Hornblende I found it now under the form 

 of Basalt (compact Felspar and Hornblende aggregated, with bril- 

 liant Crystals of Augite) which when fractured presented very 

 sharp edges. 



Some convulsion subsequent to its projection had split the vein 

 of Basalt into two masses, one of which, fallen against the other 

 rested upon it, forming a natural arch between the two, Schistose, 

 quartz, and Jaspery rocks, were associated with the Basalt, and 

 confusedly blended with it in the mass, confirming my view of the 

 passage of the Trap through the Quartz Schist. 



The surfaces of the Basalt had assumed a puce color in many 

 places. 



Scattered around the base of the vein I observed a few penta- 

 gonal basaltic blocks, mixed with fragments of jasper, Schist 



