458 Henry H. Hoicorth — Geology of the Isle of Man. 
town Bay is occupied by a famous basaltic boss, known as tbe Stack 
of Scarlet. From tbis boss lines of trap emerge in sporadic fasbion 
and may be traced in various directions, especially about the pro- 
montory of Langness, in Derbyhaven Bay, and at Cushnahavin. 
Where they have bui-st through, they have naturally altered the rock 
very considerably. It has in soxne places so altered the limestone 
that it is impossible to see any limit where trap ends and limestone 
begins. In another place, namely, close to Ronaldsway, between 
high- and low-water mark, it has broken it up into rhomboidal 
blocks by cracks running S. 40° W. and S. 30° E. But the meta- 
morphism is more important elsewhere. Let me quote the graphic 
words of Mr. Cumming himself : 
“ There is one remarkable fact which should not be overlooked, 
which is, that the Boulder-clay itself seems in some measure to have 
partaken of the metamorphosed character of the limestone. Patches 
of it here and there are hardened and cemented, and present a 
baked appearance, and have resisted the action of the sea. It is 
difficult to determine whether this has resulted from long contact 
with the ochreous mass of altered limestone, or from the escape of 
heated gases at some period of the Boulder-clay through cracks 
formed by the previous disturbances which we must thence dass as 
belonging to the Boulder period.” ( op . cit. p. 100.) The difficulty 
suggested by Mr. Cumming exists only so far as I can see because 
of bis classing the red conglomerate as Devonian. If he had seen 
that it was in fact but an altered glacial deposit, but one conclusion 
would, it seems to me, have been possible. Let me, to illustrate my 
Position, quote one more passage, and although a long one, it shall 
be the last. Speaking of the great trap dyke at Langness, Mr. 
Cumming says : — “ The ground plan of it is well worthy of a 
minute study, and the contrast of colour of the two rocks (the 
green or olive-coloured trap and the red conglomerate) renders the 
phenomena distinctly visible to even an ungeological eye. The trap 
seems to shoot out in one strong body from the schist to the east- 
ward, and may be seen as a dyke of the breadth of forty-five fect, 
where it runs out to sea, on the eastern side of the peninsula ; but 
as soon as it enters upon the old red conglomerate (sic) which over- 
lies the schist, we find it separating into branches and twisting about 
amongst the pebbles and boulders of that formation in a most 
singulär manner. Some of these branches taper off to an extreme 
thinness. We can trace them by the colour tili they are scarcely 
the thickness of a wafer. Now on the opposite side of the bay, at 
Knockruslien, we see this dyke where it cuts through the limestone 
in the same solid and compact form which it has where it cuts 
through the schist. There are there to be sure two or three straiglit 
cracks in the limestone, which have been filled up by the fluid trap 
injected from this dyke ; but the general fact which we must observe 
is this, that in the schist and tough limestone the trap dyke is com- 
pact ; in the old red conglomerate it is spread out and branching. 
And thus we come to the conclusion that the fluid trap was forced 
upwards with enormous force through the schist; that when on its 
