4 



Geology of the Country 



[July 



Museum of the College of Madras, shell-limestone found by him at 

 Paddapangallee in the Northern Circars, a few miles west of Rajamun- 

 dry, and nearly forty miles from the sea shore, underlaying basalt. I 

 was fortunate enough, in the year 1835, to visit one of those interesting 

 hills in his company ; some oyster shells are well preserved in this 

 limestone. Lately, Mr. Malcolmson of this Presidency, has given a 

 more detailed account of the geological position of the fossil shells, 

 found under the trap between Hyderabad and Nagpoor. 



These geological appearances seem to countenance what is said in 

 the Puranas, " that it has been handed down by tradition, that the 

 " greatest part of the Coromandel Coast was suddenly elevated out of 

 " the sea." (a) 



Having given the foregoing cursory sketch of the geology of the 

 environs of Madras, we may proceed to the description of the geological 

 appearances of the places examined during the two Journies. 



AHampaucum.— The monotonous plain, between poonamalee and this 

 place, offers nothing of any interest to the geologist, except the ex- 

 istence of a few straggling pieces of a chloritic slate, probably derived 

 from some of the hills which are seen at some distance. 



Near the Bungalow of Allampaucum the protruding rocks are com- 

 posed of foliated felspar of a pale flesh colour, in some places decompos- 

 ing, but not to such a degree as to form clay (No. 14). This felspathic 

 rock occasionally imbeds angular pieces of white transparent quartz, 

 and, vice versa, the quartz imbeds the felspar (No. 15). 



The surface of the soil is bestrewed with a prodigious number of 

 quartz pebbles, the angles of which are often worn down (No. 16). 

 These pebbles originate in the disintegration of the huge veins of quartz, 

 seen protruding through the soil, the imbedding felspathic rock having 

 decayed. 



These quartz veins are seen intersecting this rock close to the outlet 

 of the large tank near the Bungalow, where is also observed the two 

 minerals imbedding each other reciprocally. Not a few of these pebbles 

 have their surface of a red color, which extends for some lines into their 

 substance. It is the effect of the infiltration of oxide of iron after the 

 disintegration of the vein, since the colour of the quartz in the rock is 

 perfectly white and transparent (6). 



Goriattum. — Approaching Goriattum the country loses the flat, tire- 

 some appearance it hitherto had, and becomes hilly and pleasantly 

 variegated with inequalities of the ground, and majestic arboreous ve- 

 getation in the ravines, and on the declivities of the hills. 



(a) Heyne's Tracts, &c. But, curious enough, afterwards he adds, <c but the appear- 

 ances of the low lands renders it evident that the tradition cannot be correct !" page 1. 



(b) I think it is what Buchanan call quartz impregnated with iron.— Vol. 1. page 31. 



