Nov., 1892. 
GLACIAL GRAVELS OF THE GLOPPA. 
249 
part of the great Anglo-Welsh moraine of the ice-sheet. I 
will not here express any opinion on the point, save to say 
that I have not yet been convinced that the facts can all be 
explained by the morainic and ice-sheet theory. Mr. T. M. 
Reade, in the “ Geological Magazine ” for July, 1892, points 
out this fact, and says : “Nor must we lose sight of the fact 
that near Macclesfield, and at the Three Rock Pit, near 
Dublin, shelly sand and gravels have been found at the level 
of about 1,200ft. above the sea. These places are on the same 
parallel of latitude, about 190 miles apart. If the transport was 
by land ice, the ice sheet filling the Irish Sea must have had 
here a front of not less extension than 200 miles, and a 
minimum depth of say 2,000ft. ; but on this head we have 
very little to go by. We may very well ask how a snow-field 
in Scotland, of a less width than the distance between these 
two places, even assisted by the bordering fields of England 
and Scotland, should have generated a glacier which not only 
displaced the water of the Irish Sea, but after spreading out 
190 miles still maintained such an enormous depth as to be 
capable of forcing up sea bottom laterally on either side to the 
height of 1,200ft., and in the case of the Three Rock Mountain 
against the contributory glaciers of the Irish Sea. I under¬ 
stand that a reply to Mr. Reade’s paper is in contemplation, 
and we shall await its perusal with interest. These high level 
glacial gravels are in evidence at various points along the 
carboniferous ridge to the West of Shropshire and Cheshire, 
notably at Yrondeg (south of Minera), on the Halkyn 
Mountain, &c. These have been described by the late Mr. D. 
Mackintosh, F.G.S., in various papers. The fauna presents a 
close resemblance to that of the Moel Tryfaen deposit. By 
the courtesy of Professor Judd, I have examined the shells 
from there, which are at the Royal College of Science, South 
Kensington, and the general resemblance in condition and 
type is very marked, more so than to the Macclesfield shells. 
The fauna and the included stones correspond closely with 
those of the Cheshire Lower Boulder Clay. See D. 
Mackintosh’s paper on the coast cliffs of the east side of the 
Dee estuary. The occurrence of these high level gravels at 
such distant points as Moeltryfaen, 1,360ft., 45 miles from 
the mouth of the Dee ; Macclesfield, 1,150ft., 50 miles from 
Dee mouth, 55 from Gloppa ; Gloppa, 1,130ft., 40 miles from 
Dee mouth ; and Wicklow, 1,200ft., 100 miles from Tryfaen, 
and 190 from Macclesfield, adds much interest to the study of 
these deposits, and whatever explanation is adduced for their 
formation must account for their deposition at all these 
different places, as it is evident that they all owe their 
origin to one and the same cause, and a striking feature 
