310 Proceedings of the Royal Irish Academy. 



L. 0:S THE C0EE,ELA.TI0>r OF THE LnfES OE FaEXTEN'G OF THE PaXA^IQ-^ 



CoAL-PlELD DiSTEICT, XoKTHEE^^ IjSTDTA, WITH THE JfEIGHBOXrEEfG 



Coast Listes. By J. P. O'Reilly, C.E., Professor of Mining and 

 Mineralogy, Eoyal College of Science, Ireland. 



[Eead, Apiil 12, 1880.] 



Havetg reeeiyed fi'om llr. Valentine Ball, of the Geological Survey of 

 India, copies of his memoirs on the coal-fields of the Palamow district, 

 Bengal Presidency, to which are annexed detailed maps illustrative of 

 the geological characteristics of this district, I was led to examine 

 the very remarkable lines of faulting which these maps present, re- 

 latively to their angular correlation with the coast line Great Circles 

 passing through or near this district. 



I considered this an excellent occasion of applying the theory of 

 correlation of lines of direction submitted to the Academy in June, 

 1879, since I could have but little previous knowledge of the district 

 on the one hand ; and, on the other, the length and straightness of the 

 lines of faulting are so remarkable, that their concordance with the 

 theory should, so far, be a strong proof in its favour. The maps are 

 to a scale of one inch to the mile, and therefore sufficiently large to 

 show details with clearness. 



The only great circle, of those originally traced by me on the 

 globe, which I find to intersect the district, is that which I call the 

 Beluchistan East and West Coast-line Great Circle, or, as I shall call it, 

 the BelucMstan Coast-line. On the globe it cuts the meridian of 

 90^ E. in latitude 23° 45' 'S., at an angle of about 84° 31' W. of i!^. 

 This I have transferred to the maps, or rather parallels to this direc- 

 tion. I have further traced thereon parallels to a Line of direction 

 making, with the eastern Ghats coast-line of India great circle, an 

 angle of 40°. Its dii'ection differs from that of the Beluchistan coast 

 line great circle by about 4°, that is, it would cut the meridian 90^ E. 

 at about 88°-89° TV. of JST. Eor convenience I shaU term it " The 

 88° W. of N. LineP I might have introduced other great circles or 

 parallels to them, but the most direct proof and the simplest is the 

 best, and I therefore confine my examination to the angular relations 

 between the lines of faulting presented by the maps and these two 

 principal lines of direction. 



There are two 1-inch scale maps, the one of the Hutar coal-field, 

 the other of the Auninga coal-fielcl. 



Taking the fii'st, on which I have traced parallels to the Belu- 

 chistan coast great cii-cle, and to the 88° "W. of IS". Line, I find the 

 following angular relation for the lines of faulting, and other priucipal 

 lines : — 



