330 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



Tertiary marine fossiliferous deposits of Wexford, Ballybrack (Kil- 

 liney) and elsewhere. He gives lists of fauna, which show the fol- 

 lowing relationships: 



Extinct, south European, and boreal Mollusca from Ireland. 



The southern species at Ballybrack are Woodia digitaria and 

 Pecten glaber. He describes the section at Killiney Bay as an older 

 drift of " large and small rocks, limestone, quartz, schists, and 

 granites (many of the limestones being beautifully striated) , inter- 

 mixed with thick beds of sand, often tilted at an angle of 70° to 80° 

 to the beach beneath which they pass, reappearing at intervals near 

 the Shanganagh and Bray Elvers." 



It is overlain by the middle drifts — loose sands, gravel, and occa- 

 sional large blocks of granite and quartz. He concluded that the 

 Wexford gravels are immediately preglacial and that the Ballybrack 

 fauna is intermediate between that of the Wexford beds and that 

 of the bowlder clays and midglacial gravels. Whatever we may 

 say to the former conclusion, there seems little doubt that the Bally- 

 brack fauna is older than that of the lower bowlder clay. But the 

 Ballj^brack fauna is associated with beds which must have been de- 

 rived from an earlier glacial deposit, possibly the purple clay of Kill 

 o' the Grange. Altogether, this seems strong evidence for an inter- 

 glacial period in eastern Ireland. 



Very little is known as to the depth of the preglacial river chan- 

 nels of Ireland, but the few borings available show that the drift- 

 filled valleys extend considerably below present sea level. A boring 

 in the Lagan River at Stranmillis, 2 miles above Belfast, proved 

 bowlder clay at — 60 feet, so that the sea level must have been at 

 least 70 feet lower than now when the valley was excavated. At 

 Dublin the drift-filled valley of the Liffey shows that in preglacial 

 times the land must have stood somewhat above its present level. 

 At Cork the minimum estimate of the preglacial elevation is over 

 200 feet. 



Of later date than the general glaciation of Ireland are the local 

 moraines left by mountain and valley glaciers, as in Scotland. The 

 best developed of these wdiich I had an opportunity of studying were 

 those of the Barnes River glacier in Barnesmore Gap. This gap is a 



