XXVII PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
Mr. Nicol then proceeds to show that this accumulation of beds 
was consolidated, squeezed and upraised anterior to the formation of 
the old red sandstone, and infers that the older deposits were formed 
into hill and valley, and probably, in part at least, rose above the sea 
into the atmosphere, when the conglomerates of the old red sand- 
stone were collecting round them, tongues of old red sandstone now 
entering valleys of the older series. He also points out that the old 
red sandstone once covered the latter more extensively than we now 
find it, denudation having removed the greater part which once 
existed. 
These researches of Mr. Nicol are highly valuable in enabling us 
to trace into Scotland evidences of the general disturbance of so 
much of the older paleeozoic rocks prior to the date of the upper 
parts, at least, of the old red sandstone. Those familiar with the geo- 
logy of Southern Ireland are aware, that there the conglomerates of 
the old red sandstone repose upon the upturned and frequently con- 
torted beds of the older paleeozoic rocks, and it is not difficult to see 
that the overlap of the higher over the lower parts of the old red sand- 
stone, which commences in Herefordshire and runs through South 
Wales, is prolonged into Southern Ireland, the movements in the 
latter having been more decided and greater than in South Wales. 
If the higher portions of the old red sandstone overlapped the lower 
in Herefordshire and Shropshire, such extensions by overlap have been 
removed by denudation ; but again, in North Wales, we find the old 
red sandstone, as a conglomerate, here and there appearing from be- 
neath its covering of carboniferous limestone, the latter m its turn 
extending over and beyond the former, and both together covermg 
the upturned and frequently-contorted beds of the older palzeozoic 
rocks. Anglesea shows us the old red sandstone covered by moun- 
tain limestone, and even by coal-measures, thus overlapping older 
rocks further in that direction. In Cumberland and Westmoreland 
we have the well-known examples detailed to us by Dr. Buckland, and 
published many years since (1816) in our Transactions, and now we 
have the addition to our knowledge made by Mr. Nicol. Local cir- 
cumstances, therefore, in Herefordshire and Shropshire would appear 
to have interfered with, or so modified the great contortion and up- 
raising of the older paleeozoic rocks, observable over an area comprising 
probably the greater part of Ireland, Northern Wales, Westmoreland, 
Cumberland and Scotland, that the old red sandstone, or its upper 
portions, did not there accumulate, as a conglomerate, over portions 
of them. In the direction of Devonshire there was apparently a com- 
parative absence of crumpling and bending of beds at this time, and 
there deeper waters may have occurred, while littoral and river action 
were forming conglomerates in other parts of the area now occupied 
by the British Islands. 
When we see conglomerates, in which the water-worn pieces of 
subjacent and adjacent rocks are often large, we necessarily look to 
an adequate cause for their production, and find little else than the 
grinding together of such pieces of rock on sea-beaches, or the 
throwing or thrusting forward of shingle and gravel by rivers, capable 
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