SEE 
460 SC J. H. COLLINS ON THE SERPENTINE AND 
Fig. 1.—Sketch-Map of the Porthalla District. 
(Scale 13 inch to 1 mile.) 
/ 
( Lower Sinarian) DN See SS = 
Nelly Cov, 
“af preity Cove : 
(Yedocr) 
Beds * 
limestone exactly resembling those of Gernens Bay, and containing, 
in places. portions haying an organic-like structure, the nature of 
which has not yet been determined ; like the Gernens Bay limestones, 
they also contain minute fragments of Crinoids *. 
These Nelly’s Cove rocks are, in my opinion, certainly Lower 
Silurian, as are also the quartzites at the top of the hill (at Penare 
Farm a little to the N.W.) which were described by me in the 
paper already referred to as containing Lower Silurian fossils 7. 
Proceeding southwards from Nelly’s Cove towards Porthalla, 
. Wwesoon reach some very siliceous conglomerates containing fragments 
of a rock which, both macroscopically and microscopically, resembles, 
and is in fact identical with, the “ granulitic rock” of Porthalla. 
These beds seem to dip at low angles to the 8.S.E., as shown in the 
map. They are succeeded by soft dark schists having nearly the 
same strike and dip, only a little more to the southward, which 
form low cliffs on both sides of Porthalla Cove. On the east side 
of the rivulet they extend up to the first fault, gradually, however, 
* I believe that the specimen No. 733 collected by Dr. Boase “ from 
Porthalla,” which is now in the Museum of the Royal Geological Society of 
Cornwall, and which contains portions of an Orthoceras and other organisms, 
came from here (only half a mile from Porthalla), and not actually from the 
village or cove proper. I have searched there very narrowly without being able 
to find any limestone whatever. 
Tt Trans. Roy. Geol. Soc. Cornw. vol. ix. (read Nov. 1879). 
