3S 
Rex T. Prider. 
The. exact relations of these rocks to the eastern gneisses are unknown. 
Petrologically they appear to be vei*y similar although not so extensively 
hybridised and are only considered apart here becanse of their somewhat 
different strike. 8o far as could be seen thei'e are no remnants of slate (see 
also under ‘hpiartz veins”) in these granite-giu'isses nor any development of 
minerals which would suggest the assimilation of argillaceous material by 
the intrusive granite. There is no chilled contact, the rocks being coarse 
grained right to the contact with the Cardup sedimentary series. 
(D ). — The Cardnp Series. 
(i) The Sandstones'. 
Xear the contact with the granitic rocks the sandstones are medium 
'grained grits and as the series is traversed in a westerly direction the average 
grain size diminishes. All types are very quartzose varying in colour from 
white to i)ale yellow green, where the rocks have been considerabl}' epidotised. 
The white (juai'tzites are composed alnmst <mtirely of slightly rounded to 
subangular etpiidimensional (juartz grains (o several mm. diameter in a liner 
grained quartzose gronndmass containing occasional grains of epidote. 
Amongst the coarse grains there are occasional slightly rounded grains of 
clear microcliue — these appear to be detrital and not introduced by later 
solutions and probably were derived from the erosion of the mierocline bear- 
ing rocks to the east. 
Close to the quartzite-granite gneiss contact on the Bedfordale road a 
peculiar light greenish epidotic quartzite is often developed. This rock is 
banded, made up of layers of epidotised quartzite (giit) and layers of 
darker greenish fine grained actinolite-epidot(‘-quartzite with narrow 
irregular and lenticular bands of pale brownish cherty material. In some 
instances these cherty patches are snia.ll battened ellipsoidal bodies, scattered 
throughout the comparatively coarse grit from which they are very sharply 
defined. The stmetun^ of these chert patches is tine grained hornfelsic and 
the <'onstituents ar<‘ maiidy slightly turbid isotropic material Avith fine 
granular ([uartz, granular epidote and acicular (“?) actinolite (Z A c = 16°, 
]>ale greenisli to colourless, not sensibly pleochroic, y = 1.644). The origin 
of these peculiar cherty bauds and lenticles is obscure but they appear to be 
original serlimentary structures which have later been contact altered. The 
most probable origin that suggests itself is that they rei)rGsent small clay 
balls whidi have been flattened during the earth movements to Avhich these 
rocks have been subjected. The presence of (?) actinolite suggests that 
these balls may have been to some extent calcareous. 
The coarser gritty parts of these greenish (juartzites are similar to the 
Avhite (puirtzites with the addition of granular epidote which often occurs 
as angular grains moulded around the larger detrital quartz grains indicat- 
ing that the ei)idote has b(‘en introduced after the formation of the original 
gritty sedinumt and was j)robably derived from the quartz dolerite intru- 
sions which cut througii the sediments in this locality. 
(ii) The slates. 
Two distinct types of slate are developed — their held relations have 
been discussed above. 
(a) The black slates: these are finely bedded, dark grey to black in 
colour, different bands having varying content of graphitic material. The 
dominant constituent is fine fibrous sericite together with extremely fine 
granular weakly birefringent (?) quartz and black graphitic material. An 
interesting constituent is pale brownish green tourmaline, Avhich occurs in 
