582 



flank, the author also noticed ahorizontalbed of white limestone, 12 ft. 

 thick, containing freshwater shells and resting on granite, but covered 

 by basaltic debris. The organic remains, brought to Europe by the 

 author, have been examined by Mr. James De Carle Sowerby, and as- 

 certained to belong to two species of Gyrogonites, two of Cypris, two 

 of Unio, with numerous specimens of Paludinse, PhysEe, and Limnese. 

 The greater part are siliceous casts, but some retain their original 

 calcareous matter. Silicified portions of palm woods, and fragments 

 of vegetables, in a charred or carbonized state, also occur. In ac- 

 counting for the different state of preservation of the shells, Mr. 

 Malcolmson suggests, that the lime being in some instances retained, 

 may be explained on the supposition, that the shells weie perfectly 

 dry at the time they were acted upon by the basalt. 



With respect to the origin of this singular rock, the author is of 

 opinion that the basalt, when it was irrupted, changed the features 

 of the country, and, destroying pre-existing lakes, entangled in its 

 substance the debris and shells which had accumulated at the bottom 

 of the bodies of water, and converted the loose sand into chert or si- 

 liceous rock. Of the age of the formation, he does not pretend to 

 oiFer a precise opinion. None of the shells have been identified with 

 those now inhabiting the rivers of India ; and he is, therefore, in- 

 clined to consider them as extinct, and to refer them to the tertiary 

 sera. 



This fossiliferous chert was noticed by the author over a surface 

 extending 140 miles N. and S. ; but shells considered to be identical 

 with those collected by him, were found by Dr. Spilsbury, 18 mUes E. 

 from Jubalpore (lat. 23° 45' N., long. 78° 53' E.), in a block of in- 

 durated clay, resting on basalt* ; by Dr. Voysey, in the Gawilghur 

 range (near the table-land of Jillan)t ; by Dr. Spry, in a bed of 

 limestone, overlaid by trap, near SaugorJ (lat. 24° 15' N., long. 79° 

 E.) ; by Dr. Voysey, in a siliceous rock in the hills of Medcondah 

 and Swalpigapah south of the Godavery§ ; also at Jirpah, N. of the 

 sources of the Taptee (aboat lat. 22° N., long. 7S°E.)||. 



Comparative Age of the Formations. — On this head few observations 

 are necessary. North of Nagpoor the granite has been shown to be 

 more recent than the sandstone. The trap in the form of veins pene- 

 trates the granite, and affects, en masse, the limestone and sandstone, 

 and entangles in its substance the fossiliferous chert. If therefore, the 

 last belongs to the tertiary period, part at least of the basalt of the 

 Sichcl hills, forming the eastern boundary of the great basaltic re- 

 gion of India, cannot be assigned to one more ancient. Of the age 

 of the limestone and sandstone Mr. Malcolmson offers no positive 

 opinion, but he objects to their being considered the equivalents of 



» Journal of the Asiatic Society of Bengal, vol. ii. pp. 205 and 583. 

 ■\ Asiatic Researches, vol. xviii. p. 192. 



J Journal of the Asiatic Society of Bengal, vol. ii. pp. 376, 639. 

 § Asiatic Researches, vol. xviii. p. 193, and Journal of the Asiatic So- 

 ciety of Bengal, vol. ii. p. 304. 



11 Journal of the Asiatic Society of Bengal, vol. i. p. 247» 



