REV. E. HILL ON THE ROCKS OF GUERNSAY. 405 
hummocks, which are pitted with quarries numerous almost beyond 
counting. 
This restriction of quarries to the hummocks of the north is alone 
sufficient to prove a difference between them and the southern pla- 
teau. Should our acronaut descend to the collection of specimens, 
he will obtain from the south scarcely anything but varieties of 
gneiss. The north, however, will furnish him with a curious medley 
of rocks: some seem to be syenites and diorites; some resemble 
gabbro in structure, but contain hornblende as their principal con- 
stituent; no small number are granites; some few may be taken 
for altered rocks. Into this chaos I have been endeavouring to 
introduce some order, with less success than I desired, but not alto- 
gether invain. Previous writers have solved the difficulty by calling 
all of them metamorphic. They have not always, however, added 
evidence to assertion. 1 have tried in this paper to furnish materials 
as well as opinions. 
2. Tue Gnetss. 
The gneiss occupies all the island south of a line from Castle 
Cornet to Vazon Bay. Outcrops are seen beyond this line on La 
Ramée Road and Cobo Road ; but as the centre of the island shows 
for the most part no rock above the soil, the boundary cannot be 
exactly traced. It forms, as described above, a table-land with cliffs 
on the south and east, and a well-marked slope on the north, but 
on the west it occupies low flats extending along the shores of Vazon, 
Perrelle, and Rocquaine Bays. Andon the north too, judging from 
the outcrops above mentioned, it must extend some way into the 
central plain. Over the plateau it is shown in many road-cuttings 
and small quarries, but in these is generally very rotten and seldom 
can be studied well or at all. Our main dependence is on the mag- 
nificent sea-cliffs of the south coast. Even these for the most part 
plunge directly into the sea, and though their base can be reached 
in a few coves, and by occasional paths of more or less difficulty, it 
is rarely possible to examine more than a very few yards of their 
face. 
Seen in these sections, the rock usually consists of quartz, felspar, 
and mica—usually white, rarely black—in widely varying propor- 
tions. Almost everywhere along the coast the quartz and felspar 
are aggregated into irregular masses two or even three inches long. 
There is a rude but generally well-marked structure which perhaps 
we may call a foliation, due to a parallelism of the longer axes 
of these masses. In some places there appear to be thin intercalated 
beds (usually consisting largely of mica), coinciding in direction 
with this foliation; and whenever the bedding can be made out 
with certainty, this is certainly its direction. But there is not 
often such marked difference in materials that the direction of 
the strata can be readily identified. There can, however, be no 
doubt of the metamorphic character of the rock as a whole; its 
irregularly aggregated constituents are entirely unlike the crystals 
of a granite. The coarsest varieties are found along the southern 
