bo Epwarp Hutt—The Relations of the Carboniferous, &c., Rocks. 
Fig 6.—Ideal Section showing the relations of the Glengarifi Beds to those of later 
date in the S. of Ireland during period of maximum depression. 
yi Ty 
yy (he ‘If 
STS OO oe 
SSeS OF 
== 
Ste co oe. oGa An TS 
coll ey 
rere 
/(°) 
/ 
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——— 
5. Upper and Middle Carboniferous Beds. 4. Carboniferous Limestone (thinning Westward) 3. Carbs. Slate and Coomhola 
Grits, &c. 2. Kiltorcan Beds. 1. Old Red Sandstone and Conglomerate. G.—Glengariff Beds, 
The annexed map (Plate V.) is intended to illustrate those successive phases of 
the physical conditions of the districts now under review, and will, it is hoped, 
assist the reader in the attempt to follow the sketch I have endeavoured to give of 
these phases. 
Thus closes what seems to me to be one of the most eventful chapters in the 
Geological History of Ireland. 
EXPLANATION OF PratE V. 
This plate is intended to illustrate the areas of elevation and submersion of the British Islands during 
four definite and critical periods of its paleo-physical history, intervening between those of the Lower 
Silurian on the one hand, and of the Coal-formation on the other. These are considered to be indicated 
approximately by the portions overspread by, or destitute of, the representative strata of each period, 
allowance being made for denudation. 
The shaded portions show the areas over which the successive formations, namely, No. 1, the Upper 
Silurian (including the Glengariff Beds), No. 2, the Lower and Middle Devonian, No. 3, the Upper 
Devonian (or Old Red Sandstone), and No. 4, the Carboniferous Limestone were spread. The ‘* Lower 
Old Red,” of Scottish Geologists, is assumed to be the representative of the Glengariff Beds, and con- 
sequently of the Uppermost Silurian beds, though deposited in lakes or estuaries, and the areas em- 
braced include Professor Greikie’s “‘ Lake Orcadie ” and “ Lake Caledonia.” 
The period of least submergence was that represented in Map No. 2, during which the Lower and 
Middle Devonian beds were being deposited. These beds are considered to be represented by the 
“ Cornstone group” of Herefordshire and South Wales, deposited under somewhat different conditions 
(esturine) from those of the Devonshire beds, and are not to be found over the areas of the north of Eng- 
land, Scotland, or Ireland, which were probably land surfaces during this period. 
The period of greatest submergence is that represented in Map No. 4, when there were land surfaces 
in the centre and east of Eugland, and portions of Scotland and Ireland. The adjoining portions of 
France and Belgium are also included. 
