152 Sketch of a Classification. 



during each of which rocks of a peculiar character, distinct 

 from each other, were formed, and that there was" a trans- 

 ition or passage only between the first and second of these. 

 I appeal to those who have examined rocks in the field, and 

 not merely in cabinets and museums, whether or not the stu- 

 dent would entertain correct opinions. These divisions may 

 be said to have been made in the infancy of the science, and 

 doubtless "contributed much to its present comparatively ad- 

 vanced state; but it should always be recollected that they 

 weie formed from limited observations, and were connected 

 with particular theories, which recent and more. accurate ob- 

 servations have shown to be any thing but correct. If it shall 

 be proved that there is an occasional passage between the old 

 tertiary and secondary classes, there would appear to be more- 

 or less transition throughout the whole series of the stratified 

 rocks, showing that the term transition, at least, is incorrect. 

 A great mass of evidence is, indeed, in favour of a break at 

 the epoch of the Exeter Red Conglomerate (Rothe Todte 

 Liegende), resulting from a great derangement in the pre- 

 viously existing rocks, and the grinding and rounding of de- 

 tached portions of them into gravels, which when comparative 

 tranquility was restored, were deposited in horizontal beds on 

 the disturbed strata. Yet able observers assert, that there is 

 an occasional passage of these rocks into the coal-measures, 

 upon which they so commonly rest in an uncomfortable man- 

 ner. We have now so many instances of great differences in 

 the mineralogical structure of the same formations, either ori- 

 ginal or consequent on disturbance, that such stricture is no 

 longer a character of importance ; and it yet remains to be 

 seen how many of the strata supposed to belong to the primi- 

 tive class are altered rocks. 



M. Brongniart's division into " Sediment Rocks" would be 

 both natural and useful were it certain where such rocks com- 

 menced, and that all those necessarily included in the class 

 were so formed. This division has been much used in France 

 of late, and would appear infinitely superior to the terms 

 secondary and tertiary. 



In offering the annexed sketch of a classification of European 

 rocks to the attention of the reader, it is merely my intention 

 to show that divisions can be made for practical purposes, 

 independent of the theoretical terms primitive, transition, 

 secondary and tertiary ; terms which not being founded on an 

 enlarged view of nature, but grounded on peculiar views, now 

 doubted, there would appear no good reason for preserving. 

 It is not presumed that this classification will be adopted, and 

 I am well aware that many just objections can be made to it ; 

 but it pretends to nothing beyond convenience : and if geolo- 

 gists could be induced to use something of this kind, or any 



