G. A. Lebour, and W. Mundle — Coalin Chile. 507 



raneous deposits being formed of totally different materials, and 

 containing different organic remains. The one, the black beach, 

 made up of the debris of volcanic rocks, and containing estuarine, 

 and possibly even fluviatile, animals and plants ; and the other, a 

 white sandy beach, composed of the debris of Tertiary sandstones, 

 and having a purely marine littoral fauna. This, we believe, which 

 we see at work now, was at work then, and we thus have the true 

 key to the meaning of the want of resemblance which exists between 

 the numerous coal-fields of the same age, which are situated all 

 along the coast of Western South America. And, to render the 

 analogy between the recent case and the ancient one more striking, 

 we may remark, that the spur of rock which separates and causes 

 the dissimilarity of the two beach-deposits is the very same one 

 which divides the coal-field of Coronel from that of Lota. Seldom 

 can one see so completely the little change which Time brings about 

 in the manner in which Nature works. With regard to the geological 

 age ^ of the Coal-bearing formation, we have little to say beyond 

 this, that the belief of Darwin, that these beds belong either to a 

 very old Tertiary epoch, or possibly to an era intermediate between 

 the Secondary and the Tertiary, seems to us to be as near the truth as 

 it is possible to arrive at, with the scanty lists of fossils at our dis- 

 posal. Among these we find none that have not been enumerated 

 before, either by Darwin or by D'Orbigny ; therefore we shall limit 

 the palaeontological portion of this paper to quoting the list given by 

 Darwin (see Appendix). 



A comparison between these Coal-fields and other well-known 

 Tertiary ones might seem, at first sight, appropriate ; but the peculi- 

 arities, both of age and manner, of deposition appertaining to the 

 beds in question, preclude the possibility of their being brought" 

 into the same category as either the German Braun-TcoM formations, 

 the Bovey-Tracey lacustrine deposits, or even as the Brazilian coal- 

 bearing rocks of the river Jaguarao, which, according to Professor 

 Agassiz, belong to the true Carboniferous period.^ 



Before concluding this paper, it is necessary to say a few words 

 respecting the faults which dislocate the district we have been 

 examining. Of course we are as yet only enabled to speak of those 

 which have been observed, and proved in the carrying on of mining 

 operations, the principal of which will be seen marked in the hori- 

 zontal sections which illustrate our remarks (see Figs. 2, 3, and 5). 



F 



Fig. 5.— Section of Coal-bearing Beds at Lota, Chile. 



' This I hope to consider more fully in another paper. — G.A.L. 

 2 " Eeports respecting Coal," Blue Book, London, 1867, p. 23. With Professor 

 Agassiz' s decision I am however disposed, with all deference, to differ. — G. A. L. 



