of the European Rocks. 443 



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 

 tranquillity 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 unconformable 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 structure 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 se- 

 condary 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, inde- 

 pendent of the theoretical terms primitive, transition, secon- 

 dary and teitiary ; terms which not being founded on an en- 

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

 doubted, there would appear no good reason for preserving. 

 It is not jjresumed 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 

 other that would better answer the purpose of relieving us 

 from the old theoretical terms, I cannot but imagine that the 

 science would derive benefit from the change. 



In the accompanying Table, rocks are first divided into stra- 

 tified and unstratified, a natural division, or at all events one 

 convenient for practical purposes, independent ol the theore- 

 tical opinions that may be connected with each of tliese two 

 great classes of rocks. The same may perhaps al.'^o be said of 

 the next great division ; viz. that of the stratified rocks into 

 superior or fossififerous, and inferior or non-fossiHI'eious. The 

 superior stratified or fossilii'crous rocks are divided into groups, 

 nearly the same as those which I published in the Annalcs dcs 

 Sciences Nalurcllcs for August last. 1 have myself found them 

 useful in ])raclice, more particularly in the examination of di- 

 stricts distant from each other. 



3 L 2 Stuati- 



