1845.] Notes on the South Mahratta Country, fyc. 279 



quartz, granitie, and from the hypogene schists, with a few of cal- 

 cedony ; the sands containing grains of magnetic iron. The boiling point 

 of water at the plateau of sandstone from which the cataract falls, 

 gives 2817 feet above the level of the sea. 



The mean temperature of the place, approximated by Boussin- 

 gault's method, is 78°, which I should think rather too high, as the 

 temperature of a spring close by was only 75°. Temperature of air in 

 the shade at time 78°. 



The mean temperature of Darwar, which stands much lower, is cal- 

 culated by Christie at 75°. 



The head of the fissure, which is elliptical in form, with mural sides 

 of sandstone, has much the appearance of having been cut back, like 

 Niagara, by the abrading action of the water, for the space of about 

 100 yards. Large rocks, with angular unworn surfaces, evidently dislodg- 

 ed from the rocks on the spot are seen in the bed, and on the sides of 

 the river below the deep basin-receptacle of the fallen waters and on 

 its margin. The great hardness and compact structure of the sand- 

 stone above the falls offers great obstacles to their rapid recession. 



The cliffs, however, flanking the right side of the river below, are 

 rent by nearly vertical fissures from summit to base, by one of which 

 I descended to the bed. The direction of two of the largest was about 

 E. S. E. They are crossed nearly at right angles by minor cracks 

 which thus insulate portions of the rock. The bases of these totter- 

 ing pinnacles are often undermined by the action of the water, and the 

 mass tumbles headlong into the stream. 



The sandstone in its lower portions is interstratified with layers of 

 shale, the softness of which facilitates this process of undermining. 

 These shales are of a purplish-brown and yellowish-brown colour, 

 with minute spangles of mica disseminated, and between the laminae 

 contain incrustations of common alum (sulphate of alumina). The 

 alum is earthy and impure, and sometimes has a mammillated surface 

 resembling the alum incrustations in the ferruginous shales cresting 

 the copper mountain near Bellary, It is found in considerable quan- 

 tity in a small cave near the foot of the falls. 



The ripple mark, so often seen on the sandstones of Europe, is 



observed in great distinctness on the tabular surfaces of the cliffs and 



in the exposed layers of the subjacent beds, at least 100 feet below the 



2 R 



