The Geology and Pjiyskxjhai’hv of 'phe \\'on(U)N(j-Gakui f Area. 
1. Quartz veins in the granite gneiss. Tiiei'e are two types: — 
(a.) The small north-south striking vein south of Heenyup Ilrook. The 
vein averages five feet in width and is i<lentical witii tlie eorresponding 
type of ^M;)low'’ at Armadale. It eontains seri('ilie i)ands, and in thin 
seetion shows eataelastie stnudures and reerystallised serieitt*. Tins 
-suggests a replaeement l)y ([uartz along a shear /one. 
(b) The north-west striking blows, wliieh cross the B(‘enyup Brook. 
These are, on the avei'agc', 4 feet wide an<l may be tra('ed contimunisiy for 
distances up to 10 (diains or more. No seri<'ite bands are obser\(Ml in thes(‘. 
Fresh spe(dmens of the (pun't/ ai'e gre('nish-grey, massive and freqiuml.iy 
eontain lattu’ (luai't/ veirilets and i)yrite. On joint surfaces which have been 
bleached by weathering, angular fragnu'uts of (|uart/ up to 4 inches long 
are seen to be set in a tine-graiiuHl cherty matrix. Thin veinlets of later 
■quart/ traverse both the fi-agments and the matrix. 
Th(‘ {(uartz in tlie angular fragments shows strain and eataelastie struc- 
tures. A small amount of fels}>ar is |)r('s('nt. The (u'vslals are pi'ol)ably of 
microcliiK', they are allot riomorphic and slightly roun<h*d. 
The ground mass is tine graiju'd (piart/, through which, in the 
unweathered rock, shreds of chlorit<‘ ami biotite are distributed. 
This evidence suggests that these blows are not siinph' replacement 
bodi{‘s fornu'd alotig shear /oiu's. Th(\v may rei)resent (piart/ retd's, whicli 
after their formation, have btaui sheared and tlum partly rt'plat'tsl by latt'r 
quart/. 
‘2. Quart/ vtdns in the (kirdup Scries. These art*: — 
(a) (Quartz Blows in tlie slates at Cardup. 
There ap]>ears to be two parallel series of tjuariz blows, striking north 
and south in tlu' slatt's at (kirdup: 
(i) Tin* westerly series which is tlu* more strongly d(‘V(do)>(‘d. Tliese 
average 5 fetd in width and outertq) continuously for distances of more than 
10 chains. A section of out* of the blows ol’ this serit's is to be semi in the 
east wall of tin* main Cardup (luarry and it apjiears to Ih‘ mad(‘ uj) of bullxuis 
quartz hmses up to 4 feet wide, dipping at 85° to tin* west. These hmses 
app(*ar to conform (in strike and dip) to tlu‘ slate which has Ixhui distortisl, 
so that the bedding now 1‘ollows around the (“dge of th<* (luartz hmses. 
(ii) Th(‘ easterly series which outcrops in a north striking zon(‘ s(»m<^ 
5 or () chains to llu* east ol' (i). 44iese veins ari' lenticular and tiie lenses are 
more elongated than in (i). They conform to tlu* dip and strike of the slate. 
Under tlu* uiicroscop**, tlu* (piartz in (i) and (ii) is pi'ai-tically identical 
as regards intensity of shearing. Weathered outcro[)s may lu* massiva* or 
■show a pseudo gneissic structure caust'd by line IVrruginous str(*aks. This 
structun* is c«l by later (piartz \'eiidets, up to oiu* inch wide, in which vughs 
’Occur. 
The (piart/ is int(‘ns(*ly slu'ared and !arg(* crystals (including those of' 
lat(‘r v(*inh*ts) show slicing and giauiulation. 
Thin shreds of gr(*(*nish ph'ochroic chlorite (?) arc; arranged ])arallel 
to the lines of granulation. Twisted i>lates of muscovit(* occur s})ars('ly and 
iron ore in subhedral grains is common. 
