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coloured dolerite interstratified with a hard, white and grey 

 and carbonaceous shale, white and grey sandstones and hard 

 quartzose grit. Trap dykes and intrusions of the Rajmehal 

 age are also abundant in the coal fields of the Damodar 

 valley and dykes and cores of Basalt are common in Birbhum 

 S. W. of Rajmehal. Trap-dykes diminish in the Damodar 

 valley from E. to W. until in the S. W. of Hazaribagh 

 volcanic intrusions disappear almost entirely. Further west, 

 of course, occur the newer (Cretaceous) Deccan trap. The 

 focus of eruption of the Rajmehal trap is at a point North of 

 Raniganj. The Rajmehal beds extend to the east coast close 

 up to Cuttack and southwards. Eastward, trap-dykes are 

 less numerous but they occur throughout the upper Son 

 valley and they gradually die out in Palamau only 200 miles 

 W. of the ground in which the older lava flows of the 

 Rajmehal age are seen and within less than 100 miles of the 

 Gondwana basins in the Upper Damodar valley which are 

 traversed by basalt dykes probably of the same age as the 

 Rajmehal traps. 



30. The Gondwana rocks appear in Bengal in the Damodar 

 valley and in Chutia Nagpur. In the former, the upper and 

 the lower Gondwana rocks are both observable at the basal 

 portion of the Panchet hill and the Zemindari of Panchet, 

 south of the Raniganj coal field. The lower Panchet beds 

 consist of coarse felspathic and micaceous sandstones, usually 

 white or greenish white in colour, with bands of red clay 

 interstratified among the sandstones. The Panchet and 

 Damuda rocks though often occurring in close proximity are 

 of different age. The Panchet rocks are distinguishable from 

 the typical Damudas by the presence of red clay and the 

 absence of carbonaceous shales, and by the sandstone 

 being usually more micaceous. Fragments of coal and 

 shale are found in the conglomerates of the Panchet group, 

 but they are evidently derived from the Damudas. The 

 Dubrajpur rocks consisting of ferruginous sandstones and 



