Prof. Dr. Ferdinand Roemer — A Visit to Ireland. 61 



This great manufacturing and business-like town, which is rapidly- 

 increasing, and threatens soon to exceed Dublin in the number of its 

 inhabitants, lies at the edge of the great basalt plateau of the county 

 Antrim, which here, as on the north coast at Portrush, falls towards 

 the sea with a steep descent, and likewise covers the chalk and other 

 sedimentary strata. These characteristics are strikingly prominent at 

 Cave Hill, which is a steep and rugged mountain over a thousand 

 feet high (1188 ft.), and about an hour's walk from the town. Here 

 again the White Chalk crops out from under the basalt, the latter 

 not being of a distinct prismatic form, but generally taking the com- 

 position of amygdaloid. Extensive quarries, in which the basalt is 

 exposed, supply the finest views of its contact with the White Chalk, 

 the divisional line being very distinct, from the great contrast of 

 colour between the two rocks. It is not always horizontal, but runs 

 in many parts very irregularly, and the basalt in many places sinks 

 deep into the Chalk. Moreover, veins of basalt penetrate the Chalk 

 in various places. Under the White Chalk another division of the 

 Cretaceous formation is clearly observable, viz. a dark-green marly 

 Greensand, containing Exogyra conica, Pecten asper, remains of Cal- 

 lianassa, and other fossils, by means of which it has been without 

 hesitation classified by British geologists with the " Upper Green- 

 sand," and by D'Orbigny with the " Etage Cenomanien." At a 

 short distance from the quarries other sedimentary rocks show them- 

 selves ; the Lower Lias, the Rheetic, the Keuper, and the variegated 

 sandstone, " Bunter Sandstein." The Lower Lias is without any 

 doubt determined by Gryphcen arcuata and other characteristic 

 species; the Eh?etic is likewise distinguished palseontologically ; the 

 Keuper, a succession of red and green marly slates, interspersed 

 with thin strata of sandstone containing mica and veins of gypsum, 

 is easily distinguished ; finally the variegated sandstone ("Bunter") 

 appears in the plain along the sea-shore as a red sandstone, the 

 boundaries of which on the side of the Keuper are often difficult 

 to determine. " 



Between the Lower Lias and the "Cenomanien" Greensand all 

 the other members of the Jurassic and Chalk formation are wanting, 

 and accordingly the Upper Lias, the whole of the middle and upper 

 division of the Jurassic formation, both lower members of the Chalk 

 formation, the Neocomian and the Gault, are absent. The same 

 rule holds for the whole of Northern Ireland, and this wide gap in 

 the regular succession of the sedimentary strata is one of the most 

 remarkable phenomena of the geognostic constitution of the country. 



With respect to the Keuper, it was a novelty to me to learn that 

 here this formation, as in Cheshire, and other parts of England, 

 contains massive beds of rock-salt. In the neighbourhood of Car- 

 rickfergus, to the northward of Belfast, a rock-salt pit (Duncrue) 

 has been worked for the last few years, from which, in the year 

 1873, there was obtained over 19,000 tons of rock-salt. 



We should willingly have made a longer sojourn in this remark- 

 able country, especially for the purpose of visiting the granite of 

 the Mourne Mountains, south of Belfast, celebrated for their beautiful 



