206 



Geological Society 



[July 



imbedded. Ninety miles S. W. of Nagpoor traces of coal were notic- 

 ed, and in the hill of Won (lat. 20« 6', long, nearly 7%) Mr. Malcolm- 

 son found the cast of apparently a hollow vegetable, the only trace of 

 an organic body observed 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 Nagpoor 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 liat summit of the mountains ; but in the same district, 

 and at no great distance, it occurs on a level with the plain. 



Tertiary Strata. — Musses 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 considerable 

 areas in the Sichel bills. In a precipitous descent, on the northern flank, 

 the author also noticed a horizontal bed of white limestone, 12 ft. thick, 

 containing freshwater shells and resting on granite, bat covered by 

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

 have been examined by Mr. James DeCarle Sowerby, and ascertained 

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

 with numerous specimens of Paludinte, Phys8s, and Limnese. The 

 greater part are siliceous casts, but some retain their original calcare- 

 ous matter. Silicified portions of palm woods, and fragments of 

 vegetables, in a charred or carbonized state, also occur. In accounting 

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

 suggests, that the lime being in some instances retained, may be ex- 

 plained on the supposition, that the shells were 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 sub- 

 stance the debris and shells which had accumulated at the bottom of 

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

 ous rock. Of the age of the formation, he does not pretend to offer a 

 precise opinion. None of the shells have been identified with those 

 now inhabiting the rivers of India; and he is, therefore, inclined to 

 consider them as extinct, and to refer them to the tertiary aera. 



This fossiliferous chert was noticed by the author over a surface ex- 

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

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



