252 



THE GEOLOaiST. 



It is somewhat remarkable, tliat over this district many rocky emi- 

 nences and ridges, which do not attain to an elevation of much more 

 than 1060 feet, are quite free from the Drift, which in some localities 

 reaches a height of 2000 feet and over it. Such, for example, is the 

 case at the Hill of Carrignaspirroge, to the west of Macroom, and to 

 the north of the head of the Bardinch Eiver. Without doubt this 

 deposit once covered all the hills of this range, up to their very 

 highest summits ; but some local currents must have subsequently 

 removed it while the district was being slowly raised above the level 

 of the sea. 



In the northern portion of the county of Tipperary there are some 

 fine examples of glacial action and perched boulders. 



Mr. AVynne, of the Geological Survey of Ireland, in his explana- 

 tion to sheet 135 of the Geological Map, alFords us some very valuable 

 information on this point. 



He remarks that Limestone Drift w^as recognized at considerable 

 elevations on the northern slopes of the hills about Killanafinch. 

 Large blocks of granite occur south of Toomeyvara, which have been 

 transported from the county Gal way. 



Along the high ground which rises south of Money gall large 

 boulders of limestone are scattered over the hills, especially about 

 Busherstown, where they attain to a height of 500 feet above the 

 sea. On the top of Loyer Hill, south of Moneygall, at a height of 

 about 890 feet above the sea, a large block of limestone occupies a 

 very conspicuous position ; it measures 12 feet X 9 X 7i, and it rests 

 on Lower Silurian rocks. 



On the summit of the well-known mountain called the Devil's Bit, 

 near Templemore, and at a height of 1583 feet above the sea, Mr. 

 AVynne discovered glacial striae and erratic blocks of Silurian grit 

 on the surface of the Old Eed Sandstone ; the direction of the striae 

 io from N.N.W. to S.S.E. 



The occurrence of glacial strias at this great elevation affords fur- 

 ther evidence of the enormous lapse of time during which the South 

 of Ireland lay submerged beneath the glacial sea during the last 

 Pleistocene period ; such scratches and grooviugs on rock surfaces 

 were produced beneath comparatively shallow water, and the total 

 amount of elevation of the land during this glacial period is thus de- 

 fined with tolerable certainty. 



The facts just detailed may be regarded as the most important and 

 obvious of those relating to the evidence of glacial action over the 

 South of Ireland. 



