160 Dr. Berger on the Geological Features 



C. Sandstone Formations. 



On the skirts of that elevated district in the county of Antrim 

 and in the eastern division of Londonderry, which is occupied by the 

 more recent floetz rocks (namely lias, green sand and chalk, sur- 

 mounted by a vast cap of basalt) extensive deposits of sandstone 

 occur, forming the basis on which this lofty platform appears to 

 repose. 



These deposits of sandstone appear therefore to be in every in- 

 stance of greater antiquity than the lias which they support, they 

 seem also to be partly coeval with and partly more recent than the 

 formations already described, as they are seen either alternating with 

 or overlying the members of those formations where they can be 

 traced in connexion with them. 



They may be considered as identified partly with the coal sand- 

 stones of England, and partly with the formation here known by 

 the name of red rock marie, the lower beds of these deposits being 

 referable to the former class of rocks and the higher which contain 

 gypsum to the latter; to ascertain however the precise demarcation 

 of these subdivisions is a task for which materials are as yet 

 wanting. 



A further difficulty occurs in two Instances, namely, at Cushen- 

 dall bay and at Murloch bay, where these deposits are brought ap- 

 parently into contact with the old red sandstone, without the inter- 

 vention of the coal measures or their associated limestone, so that it 

 is hardly possible to assign the points at which the old sandstone ter- 

 minates, and is succeeded by these younger members of the same 

 family. 



The sandstones intended to be described in the following article, 

 occupy the following localities. 



