412 Henry H. Howorth — Geology of the Isle of Man. 
surface. The latter rests immediately on the schist, and I have 
a number of specimens broken off from the very point of contact, 
where unmistakable schist is immediately in contact with unmistak- 
able limestone, and nothing intervenes between them, the beds at 
the same time resting apparently conformably one upon the other. 
Tliis may be seen at Cushnahavin, a few yards north of the estuary 
of the Santon brook ; a few yards to the south, as I have said, the 
purple schists may be also seen in immediate contact with the 
limestone, showing that no Devonian beds intervened. 
Fourthly, as to the red colour of the beds. This is undoubted, but, 
as I believe, it has nothing to do with the beds being Devonian- At 
the mouth of the Santon brook may be seen a sight which Mr. 
Cummiug rightly considers as one of the most interesting which a 
geologist can see anywhere. The twisted and contorted schists 
gradually change colour, and from being of a blue, and grey colour, 
become striped with red bands, which are occasionally a foot and 
a foot and a half in width, and eventually the whole rock, without 
changing its character, assumes a beautiful purple colour. The 
brook passes right through these purple schists ; some ten or fifteen 
yards to the south of the brook the schists lie directly against and in 
contact with the great beds of Mountain Limestone. At the point 
of contact, and some distance beyond, the limestone is coloured of a 
russet colour by iron. There are no interposed beds of red con- 
glomerate, but the schists and the limestone are both of them stained 
red with iron for some distance from the point of junetion. Further, 
I was told by a neighbouring farmer that a shaft had been pierced 
into the limestone at the point of contact in search of iron-ore, 
which had been found there. 
Where the schists and the limestone are in contact at Port Sh 
Mary, a similar excavation for iron has been made, and the limestone 
beds are stained of a russet colour. 
The same thing occurred in Castletown bay on the peninsula of 
Langness, where the deep blue slate may be studied in its normal 
condition, both at the extremity of the headland and at a recently 
sunk shaft made in search of copper about 500 yards from the 
extremity of the headland. The schist between the two points just 
named gradually changes colour and becomeS' highly charged with 
iron, while the beds of limestone which lie in the bay go through a 
similar change of colour. This shows that where the schist and the 
limestone came into close contact, there has been a discharge of iron 
which has discoloured the rocks on either side. This discharge 
probably proceeded from one of the numerous trap veins which have 
dislocated the rocks in a very extraordinary manner, and whose 
meandering lines are very clearly marked against the differently 
coloured rocks close by. It is this discharge of iron at this critical 
line of junetion between the limestone and the schist which may 
possibly have led to the idea of there liaving been a series of Devon- 
ian beds between the schists and limestones in the south of the Isle of 
Man, but I am confident that no such Devonian rocks exist in that 
part of the island. I do not say a word about the red sandstones of 
