408 REV. H. HILL ON THE ROCKS OF GUERNSEY. 
the quarry by St. John’s Church, the quarries on Les Genats Road, 
and parts of the shore east of Fort Le Marchant. Again, at the 
same point, we may find the rock varying in a manner seemingly 
capricious, as may be seen a few yards south of Fort Doyle. 
Fourthly, there is the evidence of the contact between these rocks 
and the gneiss. On the west coast, though they are found extremely 
near it, about Cobo, yet I have seen no actual junction. Neither is 
it likely that any will be found in the centre of the island. But on 
the eastern side, though the harbour of St. Peter’s Port occupies the 
general position of the junction, still in the rocks exposed at low 
tide on the north side of Castle Cornet breakwater, I believe an 
actual junction can be seen*. Even here to trace it is no easy 
task. The rocks are masked by quantities of sea-weed and shell-fish, 
intersected by a network of small infiltration veins, and torn by 
intrusive dykes in extraordinary variety and abundance. The 
gneiss, however, is tolerably easy to distinguish from the rest, and I 
certainly believe that the same rock that is found along the shore 
north of the harbour does occur here also, cutting sharply across the 
foliation of the gneiss and running into it with an irregular boundary, 
which can only belong to an igneous rock. 
Lastly, Professor Bonney, from his independent microscopic 
examination, describes the whole of this series as igneous. 
This mass of evidence is conclusive. Yet I long thought that 
Ansted might be right about the metamorphic character of these 
rocks. For though neither he nor any one else mentions any place 
where the bedding could be seen, I have myself discovered three 
spots where there are strong appearances of stratification and dip. 
These are all on the east shore of the north extremity of the island, 
and within a space of about halfa mile. The southernmost, in some 
rocks near Pt. Norman Battery, consists of a lamination or banded 
structure dipping about 60° N.E. by N. There is a laminated slaty 
band and a sort of cleavage in the blue dioritic rock in which the 
slaty band occurs. The appearances here are not very striking, and 
are probably due to a dyke (the slaty band) and a platy jointing 
parallel to its walls. The next instance is a quarter of a mile 
further north, in a sort of bluff a few hundred yards south of Fort 
Doyle (fig.1). Here a set of four or five deep grooves weathered in 
the rock belong to a series of parallel planes which dip at about 
20° towards the west. These grooves correspond to some difference 
of structure, and there is a slight banding which appears to correspond 
to them in a quarry a few yards off. Very little difference is visible 
in unweathered fragments of therock. They seem to me to resemble 
the banded structure developed by pressure in certain igneous rocks 
(as in gabbro at the Lizard, described in Quart. Journ. Geol. Soc. 
XXxlll. p. 903) rather than any truly stratified beds. 
The last, and by far the most striking of these appearances, cuts 
right across the craggy headland on which stands the small fort called 
Fort Doyle. It consists of a well-marked set of slaty beds about 8 
* These rocks are now being blasted away to improve the entrance to the 
harbour. 
