250 
C. E. S. Davis. 
Outcrops urc poor, and sandstone rubble often obscures slate and 
cons-lomerate beds. There are thin bands and lenses (from an inch to six 
inches thick) of arkoso in slate and bands of sandstone in eoin>foinerate 
so that the succession deduced from exposures in pits just north of Ellis 
Brook has been sh<>hlly generalised. It is, in descending order:— 
llematitic Sandstone 
? (M'estern bound 
obscured.) 
Sandstone with Cherty lenses 
30 feet. 
Slate . . 
20 feet. 
Conglomerate 
24 feet. 
Vughy Sandstone (with barite) 
8 feet. 
Basnl Conglomerate 
15 feet. 
Although coarser-grained than those which have been worked at 
Armadale and in the Wongong-Cardup Area, the Gosnells slate is of excellent 
quality for brickmaking. Shallow trenches have been dug to jirove its extent 
and it is (‘xpected that, although tlu' slate crops out oven' such a small area, 
it will bo workod in Iho near future. 
The eontnet. between stnliments and ,u']‘anite is nowhere oxi>osed, but it 
may be mapped within five feet on the hill just nortli of Ellis Flrook, and 
within JO yards in several otlun- |)laees. No i»-ranite apophyses are i'ound in 
the sediments, and small (juartz veins in the granite may continue riu'ht to 
the contact but do not intrud(‘ the sediments, j’nst as has been fotuid at 
Aiimulale (1 iid(*r, 1041, j). ,30). This indicates that the Cardup scu'ies is 
younger than the granite and (piartz veins, a coiieliision which is consistent 
witli their very low grade of metamorphism. 
E. Basic Dykes. 
All previously mentioned rocks lun e been intruded by epidiorite dykes. 
Most of these dykes trend slightly west of north Avith dips (where nieasur- 
al)ie) to the east at 60°. A Lew trend north-west, or very rai'oly, due west. 
Their width vai'ies from five inches to about five chains — it is usually 
about a chain. Ln the (-entre of the wider dykes expos(‘d in the fpiarries, 
^dadde)-" joints (Balk, 1937, p. 97) are developed jierjiendicular to the dyke 
walls, but their marginal three feet is s('histose and contains segregations 
and veins of quartz, pyrite, calcite and epidote. Epidote veins may thread 
the epidiorites and also enter the surrounding granite. 
I bin, irregular, basic veins (nowlu're move than two feet wide) have 
been exposc'd in the AVhite Rock (^luarry. They occupy joint-cracks in the 
gi unite and H'semble the schistose iiiarg*ins ol the dykes in niinei'alogical 
composition. 
A porphyritic basic rock (porphyritie epidiorite) intrudes the Cardup 
sediments. The dumps of two shalloAv pits dug in this rock contain small 
masses of barite, up to about four ])ounds in weight. Nothing is now visible 
to indicate further the mode of origin of the mineral. 
Non-porphyritic epidiorite dykes intrude the Cardu]) series at Armadale 
(Frider, 1941, p. 43), but no such intrusions were found over the small area 
where the sediments cro]) out at Gosnells. 
