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PAL^IONTOLOGICAL REPORT OP GEOLOGICAL SURVEY. 



The other rocks of the Coal Measures, like the deposits of iron, 

 under their different forms and compounds, are purely local, and have 

 no relation to our subject, viz : the identification of coal veins by pa- 

 laeontology. The discussion of their formation and distribution would 

 be out of place here. 



To conclude these preliminary remarks, we need only expose, in a 

 few words, the general rules which are drawn from them : 



1st. The black shales, immediately resting upon abed of coal, viz: 

 the roof shales, furnish, by their remains of fossil plants, shells, and 

 fishes, the most reliable indications for the identification of their ge- 

 ological level. 



2d. The remains of plants give for this the best characters, since the 

 vegetation of the coal beds was more generally and uniformly distri- 

 buted on large surfaces, and since the plants, by their progressive modi- 

 fications, are subject to atmospherical influence, and also to the chem- 

 ical changes of the water. 



3d. The geological distribution of the plants or shells cannot be 

 modified in a sudden and striking manner at each change of level. 

 Therefore, the presence or absence of a species in the shales may be 

 accidental, and cannot be a conclusive evidence of a change of level, 

 except after a long and careful examination over a wide area. The 

 grouping of fossil species in the shales and its variations, afford a more 

 reliable indication than the presence or absence of a single species. 



This sufficiently shows the difficulty of the work of identification, 

 in a country where a small number of beds of coal have been opened and 

 worked, and where palseontological researches have been scarcely begun ; 

 in fact, this report is only the introduction to an important work, 

 which ought to be pursued with interest by every true geologist, for 

 the history and perfect acquaintance, not only of the coal fields in 

 their general features, but of every bed of coal in particular. But it 

 must be said, that a collection of specimens, made only for the beauty 

 and the great number of specimens for show, is of little use. It ought 

 to be made with a careful record of the place, and, if possible, of the 

 true geological level in which the fossil remains are found. And thus 

 it may, by and by, help to solve some of the most interesting problems 

 of the formation of the coal, viz : 



Is there any true marine formation of the coal ? From long explo- 

 rations pursued in Europe and in America, the writer says, contrary to 



