42 BALL: GEOLOGY OF AURUNGA AND HUTAR COAL FIELDS. 



is attributable to original limitation of the area of deposit, how far to 

 denudation, is uncertain ; but that some denudation took place is pro- 

 bable, though there are no very clear sections showing unconformable 

 superposition. 



The maximum thickness of Barakar beds in the Aurunga field is 

 Thickness. about 1,500 feet. 



As a coal-bearing group the rocks of this field take but low rank ; 

 for although the quantity of coaly matter is 

 great, the quality is markedly inferior to that 

 of the coal in the other fields. 



Although the Barakar beds in certain tracts throughout the field 



do not show signs of much disturbance, great 

 Disturbance. i i -i • • p mi ■ • 



local tilting IS 01 common occurrence. This is 



particularly found to be the case along the natural boundaries, and 



appears to be attributable to lateral thrust and compression, produced in 



connection with several considerable main lines of fault. 



In many of the sections a vertical contact between the bottom beds 

 of the Barakars and the metamorphic rocks has been thus estab- 

 lished. 



In the Hutar field, although its position is so closely adjacent to that 



of Aurunga, the coal measures present many 

 Lithological cliarac- 

 ters o£ Barakars in points of striking contrast to those just described. 



In the east of the field the Talchirs are overlaid 



by sandstones and conglomerates, which form hills and plateaux having 



a stronger structural resemblance to those formed of Mahadevas than 



have the hillocks and ridges which usually characterise areas where 



Barakar rocks are found. 



In the Dauri river section., and thence westwards to the extreme 

 limits of the field, a basal zone of sandstones and conglomerates with 

 coal seams first appears, — no trace of coal being seen in the scarps of 

 the hills and sections which are passed before that river is reached. 

 { 42 ) 



