o7 
been pushed relatively farther to the north-west than the 
neighbouring rock-masses, or that these have been moved 
farther to the south-east than the limestone block. 
The Eozoon occurrence can be understood best by 
first becoming acquainted with the igneous rock, and after- 
wards working across the contact zone, in which the 
Eozoon occurs, to the normal limestone. The main part 
of the intrusive mass is a_ biotite-hypersthene-gabbro 
varying in parts of the map area to quartz-diorite or quartz- 
syenite. So far as the intrusion has been studied there 
appears to be an increasing basicity towards its margin, 
probably due to differentiation of the intruded magma. 
A quartz-syenite phase of the intrusive from the south- 
west corner of the map area consists essentially of hypidio- 
morphic hornblende, orthoclase and biotite, with smaller 
quantities of augite, micro-perthite, plagioclase, quartz, 
apatite and ilmenite. A small amount of quartz and feld- 
spar are micrographically intergrown. The hornblende is 
green and strongly pleochroic : c-very dark green, b-very 
dark green, a-greenish yellow. Occasionally it encloses ker- 
nels of non-pleochroic augite, from which it appears to 
have been derived during the cooling of the magma. This 
phenomenon is illustrated by all phases of the intrusive 
in this locality. 
The rock from the north-west corner of the area is 
composed of the same minerals, but there is no micro- 
graphic intergrowth, and plagioclase is relatively more 
inportant than orthoclase. In a diorite phase from the 
centre of the map area orthoclase becomes subordinate in 
amount, and quartz is only sparingly represented. The 
hornblende is sometimes micro-poikilitically intergrown 
with feldspar, and the latter mineral is also filled with 
minute needle-shaped inclusions. 
Other specimens, more especially those from near the 
contact with the limestone, are gabbros. Pyroxenes are 
more important than hornblende, though still showing 
incipient reaction rims of that mineral. Both monoclinic 
and rhombic pyroxenes are present. The rhombic variety 
has the pleochroism of hypersthene and sometimes occuis 
as kernels enclosed by augite. Apatite, titanite and mag- 
netite are more concentrated than in those phases which 
lie further away from the contact. 
The actual contact of the gabbro and the altered 
limestone can be seen at one or two points near the trail 
32224—7 
