994 Notes, chiefly Geological, across the Penijisula C^o. 156. 



yards in breadth between the laterite and the trap of the plain. There 

 I was unable to discover any veins of maganese either in the latter or 

 the basalt. 



The basalt of this dyke is seen, in the bank of an adjoining nullah, 

 to assume both the globular and columnar structure. 



Valley of denudation. —At the N. E. extremity of the cliffs of Beder 

 an instructive example of a valley of denudation and excavation about 

 a mile in breadth is afforded, of which the following is a Section. 

 It shows at the same time the immediate superposition of the laterite on 

 the overlying trap of the Deccan. {Plate Diagram No. II.) 



A. A. Are cliffs of laterite from 120 feet to 90 feet high once evidently 

 a continuous bed over B. B. B. sheeted trap and amygdaloid, and 

 occupying C. C. The space D. D. hard ferruginous masses of laterite. 

 Though evidently much waterworn and disrupted, they have success- 

 fully maintained their position against the transporting effects of the 

 stream, which not only stripped off the laterite and denuded the sub- 

 jacent trap, but excavated the latter to the depth of many feet having 

 the hard mass Ba. in the centre, and the valley of denudation, and 

 excavation D. D. 



This valley runs E. by S. and over the plain at its eastern extremity 

 are scattered the harder nodular fragments of the stripped laterite 

 mingled with regur, and the recent lateritic alluvium of the adja- 

 cent cliffs. 



Economical uses of the laterite of Beder. — The laterite, particularly 

 its closer varieties, has been largely used in building the city wails ; 

 in the revetements of its ditches, wells &c. and in the construction of 

 the more common cemeteries. The principal edifices, walls, and bas- 

 tions of the fortress are of the trap. The laterite quarries of Beder re- 

 semble those on the coast of Malabar and Canara, but are deeper in 

 consequence of the sectile beds, which are usually preferred, lying deeper 

 below the surface than in Malabar, where the far greater moisture of the 

 atmosphere may have some effect in preserving the moisture and secti- 

 lity of the upper parts of the rock. Both rocks harden on exposure to 

 t he air. There is little appearance of stratification in the cliffs ; and 

 on the other hand, no tendency to a prismatic, columnar, or globular 

 structure. The rock has much the appearance of those enormously 

 thick bedded sandstones, where in cliffs even of 200 feet high there is no 



