ASSOCIATED ROCKS OF PORTHALLA COVE, 459 
place referred to by the Professor and myself, a little to the east of 
the Cove :—- 
1. Crumpled shales and slates, sometimes containing veins and 
layers of quartz and flakes of mica. 
2. Greenish slates of a talcose appearance. 
3. Soft red shaly mudstones. 
4. Red and green bands of serpentine, often passing into 
5. Hornblende schist of the type characterizing the locality 
(‘* Pralla” or “ Porthalla stone”). 
6. Pinkish or greyish granulite. 
Of these rocks, No. 2 with No. 6 appear to represent Professor 
Bonney’s “‘ Micaceous group of the Archean series,” and No. 5 the 
hornblende group ; No. 1 belongs to a different and much younger 
series; and No. 4, the serpentine, he regards as intrusive. I will 
now proceed to give my account of these rocks. 
The slates and shales, as also the serpentine and hornblende schist, 
appear to me distinctly interstratified, the granulite as distinctly 
intrusive. The whole region seems to have been dislocated by 
numerous faults of at least two distinct periods, previous to which 
faulting it had been crumpled and contorted into numerous flexures, 
ereat and small. 
The mutual relations of the rocks can only be seen by scrambling 
over the fallen masses at low water, or by struggling up over the 
broken cliffs, and even then only imperfectly. The coast is strewn 
for some distance with magnificent blocks of green serpentine, 
mostly of the kind represented by specimen C. These blocks are the 
purest in colour and the most solid of all the serpentines I have ever 
seen. They are mingled with great masses of the granulite which 
have fallen from above, and with numerous fragments of the 
hornblende schist. This rocky débris is present in such great 
quantity as to completely cover the foreshore in places, so as to hide 
the stratification to a considerable extent ; butitis constantly being 
moved about by the waves, so that my repeated visits have afforded 
many opportunities of verifying the statements made above. These 
repeated visits have forced me to the conclusion that the whole of 
the rock series to the east of the fault mentioned by Prof. Bonney 
consists of stratified rocks altered im situ by a kind of selective 
metamorphism, as indicated by Sedgwick and insisted upon by 
Henwood and Budge (Trans. Roy. Geol. Soc. Cornw.), and not of 
stratified rocks traversed and disturbed by intrusive masses of 
serpentine, as supposed by Sir H. De la Beche, and now very strongly 
urged by Prof. Bonney. 
I have represented upon the accompanying sketch map (fig. 1) what 
appear to me to be the main features of the coast geology from Nelly’s 
Cove to Porthoustoe, including, of course, the special points in dispute. 
At Nelly’s Cove (called Betsy’s Cove by De la Beche), the rocks dip 
very steeply to the E.S.E.; they consist for the most part of dark 
shales, sometimes pyritous, and containing well-rounded pebbles of 
some still older fine-grained rock. There are a few bands of black 
