JOURNAL 



OF THE 



ASIATIC SOCIETY OF BENGAL 



Part II.— NATURAL, SCIENCE. 

 No. III.— 1884. 



IV. — Soine Bough Notes for the Construction of a Chapter in the History 

 of the Earth. — By R. D. Oldham, A. R. S. M., Assistant- Superinten- 

 dent, Geological Survey of India. 



[Eeceived Aug. 30th ;— Eead Sept. 3rd, 1884.] 



To the coal-miner, or to tlie mere geological surveyor, tlie exact corre- 

 lation of the rocks in different parts of the world is of little importance. 

 Little does the mine-owner reck of whether his coal does or does not be- 

 long to the carboniferous era so long as it is saleable at a profit, nor need 

 the geologist, asked to survey and report on a coalfield, trouble his head 

 about this ; but, to one who would unravel the physics or the history of 

 the earth, the solution of this problem may well be of paramount impor- 

 tance, though unfortunately often impossible of attainment ; generally, 

 one might almost say always, he has to depend on fossils, but the answers 

 these give are often contradictory or Delphic in their obscurity ; at no 

 time should they be too literally interpreted, but, like the cutcherry 

 gong in an Indian station, must be made the most of as the only 

 available substitute for a more accurate timepiece. But just as in 

 this city where there are many thousand timepieces of various descrip- 

 tions, of which probably no two keep identical time, every day the timo- 

 ball falls and the signal gun is fired to let all who may be concerned 

 know that it is one o'clock ; so in the past time-signals have been given 

 throughout the earth, by which we can determine the contemporaneity 

 of the strata in which their records have been preserved. Of this nature 

 would be a wide spread glacial epoch comparable to that which in the 

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