646 THE RED SANDSTONE-ROCKS OF PEEL. [ Nov. 1902, 
the rocks of the same age. The only other two periods of dis- 
turbance at a later date, in the British Isles, with which these 
overthrust-faults can be compared, are those of Dorset, belonging 
to the Cretaceous age,' and those of the Isle of Wight and of the 
South of England, which are post-Miocene and pre-Pliocene. 
X. THe ProBaBLe Source oF tHE LRon IN THE RED Rocks. 
In the course of the examination of the Permian rocks dealt 
with in this paper, and of those revealed in the borings described 
in the next following, I have had to consider the question of the 
origin of the large quantity of iron present in the Permian and 
Triassic strata. This iron in many cases, both in the Isle-of-Man 
borings and in the Lake District, has replaced the calcium-carbonate 
of the Carboniferous and Yoredale Limestones. ‘The idea that it 
might have been derived from the break-up of the Carboniferous 
shales was suggested to me by Prof. Lapworth. The large quantity 
of iron, present not only as sulphide but as carbonate, in the shales 
of the Yoredale Series, Millstone Grit, and Coal-Measures, is more 
than sufficient to account for all the iren, when it is considered that 
several thousand feet of shales have been denuded away, from an 
area of many hundreds of square miles, in the Northern Counties 
before the Permian age, and during the time that the Permian and 
Triassic strata were being accumulated. It is more than sufficient 
to account for the haematites of Barrow and other districts, which 
have long been recognized as post-Carboniferous. The landlocked 
seas, of Permian and 'l'riassic age, in the area under consideration, 
would allow of the accumulation of highly ferruginous rocks in 
the areas which they now occupy. I do not know of any other 
hypothesis which will explain the facts. It is very likely that 
the break-up of the Silurian and Ordovician shales has, in like 
manner, resulted in the accumulation of iron in the landlocked 
basins of Old-Red-Sandstone times. 
XI. Concrusion. 
In this paper I have laid before the Scciety the evidence as to 
the Permian age of the rocks under consideration. They fall 
naturally into line with the Permian of England and of the 
Continent. ‘Their true base is not seen in the Peel District : they 
are, however, proved, in the borings in the north of the island. 
(described in the next following paper) to rest there unconformably 
upon the Carboniferous rocks, and to be covered by the same 
series of Triassic strata as those that overlie the Permian in the 
adjacent parts of England, in the Lake District, in Lancashire, and 
in Cheshire. 
EXPLANATION OF PLATE XXXIII. 
Geological map of the neighbourhood of Peel (Isle of Man), on the 
scale of 2 inches to the mile. 
[For the Discussion, see p. 660. | 
' A. Strahan, Quart. Journ. Geol. Soc. vol. li (1895) p. 549. 
