212 STKATIGRAPHICAL GEOLOGY 



marine Devonian rocks, including representatives of the Middle 

 and Upper Devonian, while the lower series is either absent or 

 still awaits recognition. 



The correlation of the two areas may possibly be as follows : 



Ireland. Devon and Cornwall. 



Lower Carboniferous slates. Lower Pilton Beds. 



Coomhola Beds. Baggy Beds. 



Purple slates and grits. Pickwell Down Beds. 



Lower Glengarriff grits. ( Middle Devonian. 



^ Lower Devonian. 



Finally the northern extension of this Devonian Series into 

 Central Ireland must be briefly noticed. The Glengarriff Beds 

 appear at intervals in Limerick, South Tipperary, and Kilkenny, 

 comprising a purple slaty series like the Upper Glengarriff Beds, 

 passing up into a yellow sandstone and shale series like that of 

 Cork. In the Ballyhoura, Galty, and Knockmealdon Mountains 

 these beds rest unconformably on the Silurian, and hence it is 

 probable that the whole Glengarriff Series is similarly uncon- 

 formable to the older formations, which constitute what may be 

 called the " Caledonian " land. The position of this land is shown 

 by the rapid thinning out of the Glengarriff Series, and the 

 overlap of the uppermost division on to the Silurian in Clare and 

 the north of Tipperary. A similar overlap takes place to the 

 north-east in Carlow, where the Kiltorcan Beds overlap the lower 

 beds on to the granite, and to the eastward in Waterford, where 

 they lie directly on the Ordovician. 



Of the Kiltorcan Beds it need only be said that they thicken 

 to the north and east, developing a thick mass of conglomerate 

 at their base which has evidently been derived from the erosion 

 of a land lying in those directions. In Waterford and Kilkenny 

 this is overlain by reddish - brown sandstones succeeded by grey 

 sandstones and red shales, above which are yellow sandstones and 

 olive-green shales. These last are fossiliferous, containing the 

 scales of Coccosteus and Glyptolepis, the bivalve Archanodon Jukesi, 

 which was supposed to be a freshwater mollusc but has since been 

 found in association with marine Carboniferous Mollusca ; there 

 are also the remains of ferns, Palasopteris hibernica, Sphenopteris 

 Hookeri, Knorria, and other plants. 9 



C. DEVONIAN OF THE CONTINENT 

 1. France 



Marine sediments of Devonian age are found both in the north 

 and south of France, but are most fully developed in the north- 



