TIIK I'l.KlsTMCKNK SKKIE8 6-S3 



7. Ireland 



Ireland is largely covered by Glacial deposits, aliciut which 

 iniirh lias lieeii written, but no comprehensive account of them has 

 \v1 been published. Enough is known, however, to make it 

 obvious that they were accumulated under tin- sinn- i-mnlit ion.- a- 

 (host; of England; those of Northern and Eastern Ireland indeed 

 greatly resemble the drifts of Western England, but those of the 

 central and wi-.-tern districts constitute rather a ditl'eieiit type. 



The central plain of Ireland " is largely covered by a widely 

 spread mass of drift, consisting of dark sandy clay with pebble.- and 

 blocks and occasional beds of sand and gravel, which are sometime- 

 very regularly stratified. The great majority of the pebbles are 

 rounded fragments of Carboniferous limestone, whence the deposit 

 usually goes by the name of the Limestone Drift. This deposit 

 rests not only on the limestone, but sweeps up on to the flanks of 

 all the hills which rise from the central plain. In such case the 

 I, inn-stone gravel (often) becomes largely mingled with the detritus 

 of the rocks of which the hills are made, . . . but gravel almost 

 entirely composed of limestone pebbles is found up to heights of 

 1200 feet on the granite mountains south of Dublin. It spreads 

 across the lower part of this granite range, and runs down by Bray 

 into the county Wicklow, where it is covered by beds of sand and 

 marl that spread through Wicklow and Wexford over all the low 

 grounds between the mountains and the sea-coast " (Jukes). 



In some cases this Limestone Drift overlies a deposit composed 

 entirely of local rocks, as in Glenharrow, on the northern flank of 

 the Slieve Bloom. Here at a height of 800 feet the river-cliff, 

 120 feet high, exhibits the following succession : 



iv.-t. 

 Coarse drift with limestone boulders ...... 50 



Fini' laminated sand ......... 20 



Rubbly sand, with angular blocks of Old Red Sandstone, the same 

 rock lying .below ......... 



On the north-east coast there are deposits similar in all respect. - 

 to the low-level drifts of Lancashire, consisting of red and brown 

 boulder -clays, with frequent intercalations of sand containing 

 marine shells. Cliff-sections of such bed are frequent along tin- 

 coasts of Antrim and Down, and their marine origin is proved not 

 only by the shells in the sands, but by the presence of l.--i!n f.i'nmhi 

 and Leda minntit with attached valves in boulder-clay at Woodlmrn 

 Glen, near Belfast. 1 " 



Southwards these reddish clays appear to overlie the Lime-tone 

 Drift, as seen in the cliff-sections at Killiney and Ballybrack, south 



