274 STRATIGRAPHICAL GEOLOGY 



The basal yellow sandstones contain Lamellibranchs only. The 

 succeeding shales have not yielded Cleistopora, but contain Spiri- 

 ferina octoplicata and Productus bassus. The other zones contain 

 assemblages which correspond closely with those of the South Wales 

 and Bristol areas. A noteworthy feature is the great development 

 of the Dibunophyllum and Cyathaxonia limestones, which have 

 been termed the Burren limestone, from the district of that name, 

 where they are magnificently exposed. It is thus described by 

 Jukes 14 : 



"A range of hills, rather more than 1000 feet in height, sweeps 

 for about 20 miles along the south side of G;dway Bay. They are 

 formed entirely of bare rock from the sea-level to the hill-tops, the 

 only soil being found in crevices of the rock, or in patches in 

 the hollows of the valleys. This rock is all limestone, in regular 

 beds, which dip gently to the south, at an angle of 1^ degrees only ; 

 and counting from the lowest bed that rises out on the sea-shore to 

 the uppermost, which caps the summit of the hills three or four 

 miles to the southward, there must be a thickness of at least 1600 

 to 1700 feet of solid limestone shown here." 



In Limerick and Tipperary there is a similar succession, and 

 the limestone series attains a thickness of about 3500 feet, its 

 thickest member being the Fenestella limestone (1500 to 1900 

 feet), while the upper (Burren) limestone has decreased to only 240 

 feet. The same succession of limestones can be followed eastward 

 through Kilkenny and Carlow, and Fig. 93, across the Castlecomer 

 coalfield, illustrates this part of the area. 



East of Thomastown the limestones overlap the lower shales so 

 as to rest directly on the granite of Carlow, and a little to the 

 northward, in County Dublin, shales of the calp facies overlap the 

 limestones, thus giving evidence of another shore-line. 



This is confirmed by the sections on the coast of County Dublin 

 near Lough Shinny and Rush, which have recently been examined 

 by Dr. Matley 15 and Dr. Vaughan. The lowest beds there seen 

 are conglomerates and shales, indicating the close proximity of a 

 coast-line, and these are overlain by limestones belonging to the 

 Dibunophyllum zone. Still higher are limestones with Cyathax- 

 onia, overlain by limestones and black shales with Posidonomya 

 Becheri. 



Southern Counties. When the Carboniferous rocks are traced to 

 the south-west through Cork and Kerry a still greater and much 

 more sudden change takes place in the constitution of the system. 

 This consists in the introduction of what appears to be a distinct 

 group of shales and slates between the Yellow Sandstone and the 

 Carboniferous limestone, and to which Sir E. Griffith gave the 



