414 Lieut. -Colon el Sykes on a portion of Dukhun. 



but seen endways look like truncated cones. Conoidal frustra in the Gavvel- 



gurh range have been already noticed. Other insulated hills are triangular 



in their superficial planes, as the forts of Teekoneh (three-cornered) and 



Loghur. 



Escarpments. 



Stupendous escarpments are occasionally met with in the Ghats. In these 

 instances the numerous strata, instead of being arranged in steps, form a con- 

 tinuous wall. At the Ahopeh pass, at the source of the Goreh river, the wall 

 or scarp is fully 1500 feet high* ; indeed, on the north-west face of the hill 

 fort of Hurreechundurghur, the escarpment can scarcely be less than double 

 that height. On the other hand, the steps are sometimes effaced, and a hill 

 has a rapid slope. This originates in a succession of beds of the softer amyg- 

 daloids, without any basaltic interstratification ; their superior angles disinte- 

 grate, and a slope results. But most usually three or four beds of amygdaloid 

 are found between two strata of compact basalt ; the former disintegrates, 

 leaving a slope, which is not unfrequently covered with forest trees, forming a 

 picturesque belt : the basaltic scarp remains entire, or it may be partially 

 buried by the debris from the amygdaloids above ; but its great thickness 

 usually preserves it from obliteration, and it rises from the wood below with 

 majestic effect, its black front being finely contrasted with the rich and lively 

 green of its sylvan associate. It is these strata, arranged in slopes and scarps 

 repeated three or four times, and so commonly met with in insulated and other 

 mountains in Dukhun, that constitute the amazing strength of the hill forts of 

 the country, leaving a succession of natural walls encircling a mountain. This 

 feature did not escape the observation of Captain Dangerfield in Malwa, who 

 says, '^'^ Prom the great difference in the resistance made to decomposition by 

 " these trap and amygdaloid beds, their exposed ends acquire a very distinct 

 " degree of inclination and character; the amygdaloid forming a great slope, 

 " and affbrding a loose mould covered with vegetation, the trap retaining its 

 " original perpendicularity and dark bareness f.'' 



In the alternation of the strata there does not appear to be any uniformity ; 

 but the general level, thickness, and extent of a stratum are preserved, as in 

 sedimentary rocks, on both sides of a valley ; the basalt and hardest amyg- 

 daloids being traceable for miles in the parallel spurs or ranges ; but the im- 

 bedded minerals, and even the texture, vary in very short distances. 



Columnar Basalt. 

 A great geological feature of Dukhun is the occurrence of columnar basalt. 



* Plate XXVIII. fig. 1. t Malcolm's Central India, Appendix, p. 322. 



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