instances of this kind occur in every Coal-field. The sand~ 

 stones which generally enclose these remains with their 

 accustomed irregularity, are strong marks of an agitated 

 surface. How, then, can we account for appearances so 

 dissimilar ? 



" For my own part, I look upon the Coal-field of Europe 

 as the delta of some great and overflowing river ; some 

 ancient Nile, stretching its mighty arms into tropical regions : 

 at one time an extensive plain of the most luxuriant vegeta- 

 tion, — at another time a sea of waters. But I hasten to 

 conclude, lest I should waste tliat time in hypothesis which 

 may be better spent in practical observation." 



With this humble, but philosophic remark, Mr. Simpson 

 terminates his communication ; and I am sure it would be as 

 unwise in me, as it would be unprofitable to you, were I in 

 continuation to allow my imagination to run, as it might 

 wish, into the mazes of vague hypothesis. The question so 

 often agitated by the master minds of our science, is yet 

 unanswered. Facts apparently most contradictory meet us 

 at almost every step we take in the same Coal-field, but 

 especially is it so when we pass from one Coal-field into 

 another. Of this the Halifax Coal-field affords an instance. 

 In it there have not as yet been discovered any of those 

 Coprolitic remains which characterize the Wakefield series ; 

 nevertheless, we are led from its examination to similar con- 

 clusions with respect to the former existence of periods of 

 repose and periods of agitation, as Mr. Simpson alludes to 

 in his Paper just read. At one time we find the crushed 

 and broken up fragmentary remains of large arborescent 

 trees ; at another time we meet with the most delicate forms 

 of vegetable life, almost as unruffled as if they had but 

 yesterday been placed between the leaves of a botanist's 

 herbarium. 



But further, with regard to alternation of deposition, we 



