274 
i3KENDAN P. Thomson. 
B. Cardiip Series. 
The series may be subdivided into 
1. Basal sandy beds. 
2. Slates. 
1. The basal sandy beds eomi)vise sandstone, epidotie f|uart.'dte, and 
interbedded sandy slates. 
(a) iS'awd.strtMe.— This may vary eonsiderably in grain size. The coarser 
types, Avliieh can be classed as grits, contain sub-rounded quartz grains up 
to la mm. long. The matrix is often argillaceous and the (piartz grains show 
impert'eet graded bedding. 
In finer-grained sandstone on the western side of the Brickworks Quarry 
ripple-marking apjjears to be present. 
\ughs, which may liave originated by the leaching out of calcite, are 
common in the grits. These vughs are lined with smalf quartz crystals, and 
some contain white or colourless barite. At Cardup a small amount of purple 
fluorite is associated with the barite, a little pyrite and chalcopyrite are also 
present. White calcite occurs in some unweatliered stiecimens. 
hi thin section: — 
The ty])ical sandstone contains rounded to sul)-angular quartz grains 
interlocking loosely in a ground mass of micro-crystalline quartz and serieite. 
The quartz shows undulose extinction. Rounded pink zireons occur sparsely, 
but are rarely absent. In one section several small idioblastic crystals of 
tourmaline were found. 
The baritic sandstone has a gi*anular structure Avhich is obscui’ed l)y a 
mosaic of later vein-(]uartz. Angular cloudy felspar fragments (mostly 
micioeline) are common. Barite forms irregular grains and strings. Calcite 
and roumled pink zircons are present. 
(b) hpidolie Qitartzite , — This rock has been shown by Prider (1941, 
p. 40) to be sandstone which has undergone contact metamorphism, due to the 
intrusion of epidiorite. This is supported south of AYongong Brook, where 
an outcrop of the quartzite grades into sandstone and is associated with fine- 
grained epidiorite. 
The quartzite varies from a grey-green even-grained rock with a con- 
choidal tracture to a banded rock in which sandy and cherty bands alternate. 
Some of the sandy bands show grade-! bedding. Pyrite and marcasite are 
present in small amounts. 
In thin section clear rounded quartz grains are seen to be rimmed with 
a plexus of small pale green needles of an optically negative biaxial mineral 
with oblique extinction (probably actinolite). 
The quartz is strained. Epidote is present as small interstitial grains or 
as yellow-green clots. The felspar foiuns slightly clouded subhedral crystals, 
either of microcline or plagioclase. 
Small rounded zircons are common. 
The cherty bands contain inicrocrystalline quartz which is streaked with 
nearly isotropic white material and is spotted with epidote grains, 
2. Slates : — 
Black and white slates, similar to those found at Armadale, are exposed 
at the Brickw’orks Quarry and at Cardup. On the north bank of the Won- 
gong Brook, white and grey sandy slate outcrop, but no black slate is ex- 
posed. 
