THE 



GEOLOGICAL MAGAZINE. 



ISo. XXVI.—AUGUST, 1866. 



<d:r,xg-xi<tjl.-ju .^.i^moijES. 



L — Ancient Sea Margins in the Counties Clare and Galwat. 

 By G. Henry Kinahan, F.E.G.S.I. 



IN a paper that appeared in the " Geologist " for May, 1863, 

 the author, Professor King, has noticed the remarkable escarp- 

 ments that occur in the Burren Hills, on the south side of the Bay 

 of Galway. He is of opinion that they have been formed by 

 sea action during the slow upheaval of the British area after its sub- 

 mergence during what he calls the " subaqueous " or " middle 

 division" of the Glacial period, and that "every escarpment indicates 

 a stoppage in the upheaval." These escarpments, or ancient sea- 

 margins are not confined to the Burren Hills, as I have observed 

 them in various other localities, but never so continuous, nor so well 

 developed. 



In this paper it is proposed calling attention to those in counties 

 Clare and Galway. I shall first notice the conspicuous escarpments 

 in the Burren Hills, but before doing so I may be allowed to refer 

 to similar phenomena in course of formation at the present day. 



During a short visit to the largest of the Arran Islands (Inishmore), 

 at the mouth of Galway Bay, I remarked that on its south-western 

 shore the Atlantic seems now to be cutting an escarpment in the 

 nearly horizontal beds of the Carboniferous Limestone of which the 

 cliffs are composed. The general section of this escarpment is as 

 represented in Fig. 1. There are from four to seven terraces cut out 

 by the action of the sea ; one terrace by the high spring tides, another 

 by the high neap tides, another by the low neap tides, another by 

 the low spring tides, often with from one to three intermediate terraces, 

 according to the thickness of the beds of limestone, and above them 

 all is a " Blockbeach," formed of huge boulders hurled up during 

 the winter gales. The above action is what seems generally to be 



VOL. III. NO. XXVI. 22 



