ASSOCIATED ROCKS OF PORTHALLA COVE. 465 
Rock from Conglo- 
Rock near Fault. merate to N. of Cove. 
Water lost at 100° C. 0:06 ie é 
» On ignition 180 belt 160 
SUIS, ARGS SaaS 74:90 72°95 
RPREMIUNEN Ah obcials bore ac cee cee 10:20 ESR 
RIMES TOL ALON: << ccinieineeeonnceex 4:94 515 
LLERCY Fe ee 1:12 1°62 
BITES fcc ne ao eesiessie egies 0-72 0-31 
Soda (with atrace ofpotash) 5:07 5°41 
‘CE. "2: aaa arene ee Rta ae Pahg 1:46 
100:00 100-00 
EL AVIDY covsecenasesceccee os 2681 2°69 
The high percentage of soda (5 per cent.) m these rocks is some- 
what remarkable, considering the very moderate proportions of 
alumina and lime. Nevertheless the ‘“felspar” constituent, which 
is by much the more abundant, appears to be of the same kind that 
characterizes the hornblende schist of Porthalla. The rather high 
specific gravity and the almost total absence of “ striping” in the 
microscopic sections of this rock, when viewed by polarized light, 
tell the same tale. 
The Serpentine.—At a point about 60 or 70 yards to the east of 
the first fault, and succeeding the broken ground which marks the 
position of the second or great fault (fig. 4), is the first appearance 
Fig. 4.—Enlarged Plan of “ Broken ground” near Porthalla Cove. 
(Seale sq'y0-) 
een 
12, 
OX 4 
a ¥; 
MOS ¥ 
A. Hornblende schist (No. 5). 
B. Serpentine (No. 4). 
C. Red and green shales and mudstones (No.3). 
D. Micaceous or “ talcose” schists (No. 2). 
KE. Porthalla slates (No. 1). 
