and some other Stratified Deposits in the North of Scotland. 317 



southern parts of England^ must in some other regions have been modified by 

 the simultaneous operation of certain powerful disturbing forces. One excep- 

 tion to the common structure of a formation would point to no general conclu- 

 sion. But two exceptions of the same kind, occurring at a considerable distance 

 from each other, and precisely on the same line of deposit, almost compel us to 

 speculate upon the causes which have produced them, and to regard them as 

 the result of some general law. Are there then many carboniferous deposits, 

 subordinate, like those described in this paper, to the inferior portion of the 

 great oolitic series ? This question is of great theoretical and practical impor- 

 tance. In some parts of Somersetshire, beds of clay containing much carbo- 

 niferous matter are associated with the forest marble. In the well-known 

 quarries of Stonesfield there is an extraordinary development of vegetable 

 fossils, and, at the same time, the ordinary type of formation is greatly modi- 

 fied. Again, in the range of the oolites through the North-western parts of 

 Prance, a similar development of vegetable fossils has been discovered in 

 beds which are immediately inferior to the Oxford clay *. If the mode of 

 distribution and the generic characters of these fossil plants be ever reduced 

 under general laws, they will no longer be regarded as anomalies ; but will 

 form an important addition to the natural history of the beds with which they 

 are associated. The preceding account therefore, of the fossil vegetables of 

 Brora and of the East Coast of Yorkshire, may help us to the conclusion at 

 which we seem now to be on the point of arriving, by means of the labours 

 of Mons, Adolphe Brongniart, and some other naturalists. 



Whatever may have been the nature of those destructive agents which at- 

 tacked the existing materials on the earth's surface, and spread them out in 

 numerous alternations of sand, mud, and vegetable matter, thereby laying the 

 foundation for future carboniferous deposits; it is quite certain that their 

 operation was not confined to one particular epoch. Their greatest effects 

 appear undoubtedly to have been produced at a time anterior to the deposi- 

 tion of the newer red sandstone ; but the details above given, prove that they 

 have also come into action at subsequent periods : nor can we, in the present 

 state of our information, pretend to affix any precise limits to the extent of 

 their operation. In all the greater carboniferous deposits, of whatever epoch, 

 there appears however to be that similarity of mineralogical composition which 

 implies a similar mode of formation. Hence, in the oolitic series, where these 

 peculiarities are wanting, and where the several strata are developed in con- 

 formity with the more ordinary type of those formations, we may venture to 



* Annales des Sciences Naturelles, Avril 1825. 



