581 



both the limestone and schist. Where the formation is in contact 

 with the trap, the limestone is sometimes crystalline, and loses its 

 stratified structure ; and at the Pindee Ghat, in the Sichel Hills, the 

 argillaceous and siliceous ingredients appear to have separated, and 

 the latter to have collected in bands, having partly the aspect of 

 chalcedony, and in black chert. In some districts the limestone is 

 cavernous, and it is often penetrated by circular cavities, which, the 

 author conceives, were formed by the extrication of gaseous fluids, 

 in the same manner as similar cavities are now produced in the mud 

 by the escape of carbonic acid gas. 



A jointed structure, dividing the beds into rhombs, prevails in the 

 limestone, the schist, and the overlying sandstone. The strata are 

 often inclined, apparently the result of dislocation. 



At Jumulmudagur (lat. 14° 50', long. 78° 30') the limestone con- 

 tains layers of muriate of soda ; and Mr. Malcolmson is of opinion, 

 that the salt which is found in the alluvial matter, is obtained solely 

 from this formation, as he did not discover a trace of it in the sand- 

 stone. 



The limestone and shale are well displayed in the Pennar district, 

 also between the northern foot of the Sichels and Nagpoor ; and the 

 author has no doubt that they belong to the same system of strata 

 as thelimestone of Bundelcimd, described by Major Franklin*, though 

 the red sandstone of that country is stated to underlie the limestone, 

 while in the region examined by Mr. Malcolmson it overlies. 



Red Sandstone. — This formation is distinguished by containing 

 the breccia in which are situated the diamond mines of Golconda, 

 on the banks of the Kistnah, and those on the banks of the Pen- 

 nar. Where the sandstone rests upon the limestone schist, a gra- 

 dual passage occurs. The rock is more or less compact, and its 

 prevailing colours are red and white. The diamond breccia is con- 

 sidered by the author, as only a variety of the sandstone in which 

 fragments of older rocks have been imbedded. Ninety miles S.W. 

 of Nagpoor traces of coal were noticed, and in the hill of Won 

 (lat. 20° 6', long, nearly 79°) Mr. Malcolmson found the cast of ap- 

 parently a hollow vegetable, the only trace of an organic body ob- 

 served by him. The sandstone, as already noticed, partakes of the 

 same jointed structure as the subjacent limestone. It is penetrated 

 as well as overlaid by trap, and near Nagjooor veins of granite have 

 converted it into quartz rock. In the district drained by the Pennar, 

 the sandstone attains the height of 3000 feet, forming the horizontal 

 or flat summit of the mountains ; but in the same district, and at no 

 great distance, it occurs on a level with the plain. 



Tertiary Strata. — Masses and fragments of differently coloured 

 chert, a tough, white, argillaceous stone, and a greyish blue crystalline 

 rock, all containing freshwater shells, either project from the trap in 

 which they are entangled, or are scattered over its surface for consider- 

 able areas in the Sichel hills. In a precipitous descent, on the northern 



* Geol. Trans., 2nd Series, vol. iii., part 2, p. 191 e^ seq., also Asiatic 

 Researches, vol. xviii. p, 24, et seq. 



2 z 2 



