Rev. J. Clifton Ward—Geology of the Isle of Man. 5 
- island to the geologist, for here he sees a small ancient volcano dis- 
sected and laid bare. I was at once reminded of some of the ash- 
necks of Carboniferous age occurring just north of the Scottish 
border. The rough plan (Fig. 2) will help to illustrate the following 
remarks. The Volcanic rocks extend from Scarlet Point to Pool- 
vash, a distance of about a mile and a quarter, and consist almost 
wholly of ash and breccia, intersected by dykes of basalt. The 
Stack of Scarlet shows the finest development of basalt, and from 
this point there runs a dyke of the same in a W.N.W. direction, 
which, when best seen, is about fifty feet wide, but westwards it is 
much hidden under cover of cultivated ground. With regard to this 
line of intrusive basalt, there cannot be a doubt, I think, but that it 
represents an original line of eruption, the part nearest to the Stack 
being the spot where the volcanic fires first reached the surface, and 
where the vent became finally choked with large ejected blocks and 
scoriz, the basaltic lava welling up through a central fissure, and 
flowing over the volcanic breccia as it is seen to do upon the east 
side of the dyke. A little farther west along the shore the greenish 
ashy material is less coarse, and becomes distinctly stratified, this 
representing the matter falling outside the vent and becoming rudely 
bedded beneath the shallow sea. Just before reaching the bedded 
ash, other portions of the lava-flow may be seen overlying the ash, 
and exhibiting a very vesicular structure in bands. Nearer to Pool- 
vash the ash is interstratified with limestone, both the grey and the 
black Posidonian band, so that there can be no doubt but that the 
eruption partook of a submarine character. 
A second mass of vesicular basalt, with brecciated portions, occurs 
just W. of Scarlet Point ; it does not, however, seem to extend as a 
dyke, and its southern margin is hidden by the shore-line. 
The order of events would seem to have been this: During the 
deposition of the grey limestone and the bands of black calcareous 
mud, a vent was opened out through the bed of the sea—probably 
but shallow —from which many large blocks were ejected, the most 
of them falling back into the rent, while the smaller material fell at 
a little distance from the centre of eruption, and became roughly 
stratified and partly mixed up with the calcareous deposits. Then 
lava welled up from the vent (about Scarlet Point), forced its way 
through a fissure extending some distance westwards, cutting through 
the previously-deposited ash, and finally flowing over the ash in the 
form of a vesicular lava-stream, only small patches of which are now 
visible. 
The limestone immediately north-east of Scarlet Point is much 
altered, and near the junction with the basalt, as Mr. Cumming has 
observed, it is not always easy to distinguish between the two rocks. 
Some small dykes or threads of basalt among the limestone bands 
_ are very interesting in their course and behaviour. Between the 
Stack and the lime-kilns the limestone is also finely arched in places, 
and I was interested to observe the minute cracks extending along 
the summit of one arch, for the most part filled with carbonate of 
dime. The same fine curving in the thick limestone beds may be 
