225 



CHAP. XXXV. 



Upper Sandstones. 



THE peculiarity and importance of the preceding sand- 

 stone induced me to give it a separate place ; but in 

 this division are included all the others, \vhich follow, 

 of whatever character, or however technically or locally 

 distinguished. It is impossible to discriminate them 

 all as rocks, whatever may be their geological posi- 

 tions or associations: while such an attempt would 

 lead to wearisome repetitions ; since even the recorded 

 deposits consist of a very limited number of materials, 

 disposed in a similar manner. Even those which are 

 most interesting, from their geological associations or 

 from their uses in the arts, possess no distinctions as 

 mineral compounds, or are distinguished by characters 

 too vague to be described in words. 



An attempt moreover to describe accurately the 

 several geological connexions in which the rocks of 

 this division exist, would lead to geological histories 

 of the whole series of the secondary strata in every 

 part of the world ; a subject which, were it even under- 

 stood, would be beyond the limits of this work. They 

 occur through the whole range, from the lowest red 

 sandstone upwards ; and, under these several situations, 

 not often presenting any very decided differences of 

 character. Their chief distinctions are indeed derived 

 from the peculiar groups or associations in which they 

 are found in some particular country; constituting 

 those different series which have been distinguished 

 by the term formations. These groups appear to have 

 been investigated, in England, and generally perhaps 

 in Europe, with considerable accuracy: but it remains 

 doubtful whether some of these associations are not 



VOL, ii. a 



