DTJ NOTEK — ON THE SOUTH OE IRELAND. 



251 



sloping to the northwards, having the southern face of the boss preci- 

 pitous. The current sent the iceberg up the inclined plane faciug to 

 the northwards, till the shoaling of the water arrested its further 

 progress. The sudden concussion thus given to the rock detached 

 from off its precipitous brow facing to the southwards large flakes 

 of rock, and threw them one on top of the other down the inclined talus 

 at the base, just as a lot of books would lie if suddenly thrown down 

 on their sides from a previously close and vertical position. It is 

 highly probable that the iceberg here permanently grounded and 

 melted away, leaving the perched boulder which we now see on the 

 summit of the rock as the most palpable evidence of its short-lived 

 existence.* 



Erratic boulders of a syenitic granite, a rock peculiar to the county 

 G-alway, lie scattered over the country to the S. and S.E. of it, com- 

 prised in the counties of Clare, Limerick, and Tipperary, and some 

 of them are to be seen as far south as the deer-park of Mallow 

 Castle, county Cork. Hence we have a clue to the direction of at 

 least the last iceberg current. 



Many Drift boulders may be considered as local, and are due to 

 the action of shore ice, which dropped them before they had been 

 transported far from their parent site. Of this fact we have an ex- 

 ample in a large block of a very peculiar kind of light grey cherty 

 limestone, with thin earthy shale layers through it, which rests in a 

 field close to the Workhouse of Mallow. It now lies on the coal 

 measures to the south of the outcrop of the limestone, and similar 

 limestone is observed in situ is in the deer-park of Mallow Castle, 

 about two miles distant from the boulde'r, and near the base of the 

 Old Hed Sandstone hills. 



The Musheramore range of mountains, lying between Macroom 

 and Millstreet, have Drift gravelly clay resting on their southern sides 

 to the height of 2050 feet above the sea, as is apparent on the southern 

 slope of Mullaghanish Mountain. The southern slopes of Lacka- 

 baun Mountain, up to an elevation of 1500 feet, are dotted over with 

 numerous large angular boulders of purple slates and grits. On the 

 southern slope of Lackabooma Mountain, at a height of 1270 feet 

 above the sea, numerous large angular blocks of hard greenish grit 

 are scattered about. And thick accumulations of gravel and boulders 

 occur, at elevations of 1000 feet, in the various glens and river valleys 

 along the southern slope of the mountains to the N.E. of Macroom. 



* See * Memoirs of the Geological Survey of Ireland/ explanation to sheet 193. 



