GEOLOGY. 



which form a refuge for bears. Limestone occurs in various 

 form's throughout Chota Nagpur, and quarries of crystal- 

 line blue limestone are worked in Gaugpur (where, the 

 rocks are similar to those of Singbhum) and to a less 

 degree in Singbhum. 



A considerable area of the central Palamau plateau, 

 extending from near Loharsoe to Garhwa, across the junction 

 of the Ainanat, Jinjoi and Koel rivers (just north of Dalton- 

 ganj) is occupied by Gondwana rocks (Talchir and Damuda 

 series), chiefly sandstones, which are frequently calcareous, 

 and some coal. Another area of these rocks also occurs near 

 Latihar and in a few other places. 



The predominant feature of the geology of the Satltal 

 Parganahs is tne trap, which covers some three-fourths of 

 the Kaimehal hills, and trap boulders are common in the 

 valleys. 



The trap rocks are usually very homogeneous, or amygda- 

 loidal, brown <3r grey -black basalts, with a black or grey-black 

 micro-crystalline fracture, which may be conchoidal, and 

 usually breaks into sharp angular fragments. On the hills 

 near Morjhora a variety (dolerite) is found with a grey 

 fracture, with distinct blank or amber-coloured crystals under 

 the lens. This weathers grey, or red with a rough surface 

 easily* covered with crustaceous lichens. Laterite sometimes 

 occurs on the top of the trap. Underlying the trap, and 

 often including it, is a series of sandstones and grits, less 

 often shales. These beds are usually met with in the valleys 

 and outcropping on the slopes. Carbonaceous shales and coal 

 beds 4 with occasional limestone and conglomerate also occur, 

 and are often rnteibedded with the trap. The intertrappean 

 sedimentary deposits often contain plant beds. Underlying 

 the Gondwana system the metamorphic rocks are again met 

 with, and they are sometimes exposed well inside the 

 Rajmehal hills, e.g., at Chandna. They are, however, chiefly 

 noticeable on the western flanks and, outside the Bajmehals 

 proper, the small hills are chiefly composed of them. " These 



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