84 Guide to Belfast. 



interesting to note that, among Lower and Middle Lias 

 species occurring as derived fossils in boulder-clay in 

 Co. Dublin, Messrs. Sollas and Praeger found one species 

 of characteristic Middle Lias age.^ 



The Cretaceous System. 

 The rocks of this system are a very remarkable feature 

 around the edge of the Antrim escarpment. In places 

 the white chalk forms the strongest contrasts with the black 

 basalt capping, and in other places, when found in juxta- 

 position with the red sandstones of the Trias, the colour 

 contrasts are almost equally remarkable. Again, much of 

 the variety of the scenery along the Antrim coast road is 

 due to the faulting and slipping down of the strata, by 

 which means the black basalt at times would seem, to the 

 casual observer, to be interstratified with the chalk, as well 

 as penetrated by the vertical dykes of black basalt which, 

 in Eocene times, found numerous vents through long 

 fissures in the white chalk. 



The line of division between the basalt and the Chalk is 

 so strongly defined as a horizontal line that any break in 

 the continuity of that line 'is extremely noticeable. The 

 frequency of such breaks strongly calls our attention to the 

 numerous dislocations and fissures to which the crust of 

 earth has been subjected in post-Creiaceous times ; so that 

 the county of Antrim is an admirable district in which to 

 study the leading facts of dynamical geology. In some 

 localities certain beds are absent which are prominent in 

 others, suggesting investigations in the differential move- 

 ments of the crust prior to the deposition of the Cretaceous 

 rocks, or may allow us to reconstruct the hollows and heights 

 of the ancient geography of the district in late Jurassic times. 

 In close proximity to Belfast, on the slopes of Squire's 

 Hill, the following divisions of the Cretaceous system in 

 descending order are to be observed : 



5. White chalk. 



4. Glauconitic chalk, or basement bed of white chalk. 



3. Glauconitic sands and sandstones. 



2. Yellow sands, grey marls, and sandstones. 



I. Glauconitic sands. 



1 Irish Naturalist, vol. iv, p. 321, 1895. 



