110 
Rex T. Prider 
crystii liis(‘(l llow-bniultHl mist wliicli lias lieoii rractured ami tin* resultant 
blocks incorporated into the residual nia^'ina. There does not appear to 
he such a lonji' time ;;‘a[) between the two granites at Stathanis as there 
is at ('anninuf Dam (Prider, 1114o) and Armadale (Ih'ider, 1041) and both 
a])])ear to belong- to the sann- main period of granite intrusion (the Younger 
(Iranite) the pareiit magma heing of syntectic origin as outlined in the 
Canning Dam jiajuu* (Prider, 104‘), p. 14.'>). 
(‘4) 7'h(> Srricitf srlnsfs . — All the granites of this area show, on micro- 
scopie examination, the (bTects of eonsiderahle stress in the form of crushed 
({iiart/. and quartz willi undnlose extinction. The stiess has been localised 
in ce.lain zones along which the granite has been cojiverted into sericite 
schist. 'l’h(‘se shear zones (see giMilogical mai)) are distributed, fairly uni- 
i'ormly Ihronghont the ar(*a ami all -trike* in a N.N.lh dirc'clion and dip- 
st('eji y to tlie east. Tin* best develo) I'd of these shear zones is exposed in 
the railway cutting near the 18-miIe |)eg. The eleavage surfaces of ihe schist 
from this well developed shear zone are traversed by innumerable minute 
(‘ona’gations which ai’c arrange'd hori/.onlally — unfortunately these* tiny drag 
sti’uctiires are not sutliciently well develo})ed to enable* any positive deter- 
minatieni of the* nature' of the earth movemie'nts responsible for the shearing. 
Since these* corrugations are* arranged horizontally the move-ments appear 
to ha\'c hce'Ji eleiminantly vertical. 
The*re is c(uisiel(*ral>l(‘ elivci'g(*ncc between the N.X.K. eliie'ction of those 
shear zones anel the* almost due north li'end of the* Darling Scarp whiedi in- 
dicat s that the'se* shears hear no relation to the sni)))osed Darling Fault. 
(4) Qnarl: — These have* h(*en noteel in se*\(-ral place's. They have 
a general Irenel ])arallel to the* shear zones and their dii'eedion lias evidently 
l)('en controlled by the* earlie*r iinpe)se‘d shear pattern. The* oce-urrence and 
jict 'ology of the (luactz veins and shear zones in the Darling Scarp have been 
sufficie*ntly dealt with in jirevious ])u})lications (Clarke ami William'^, 
]). 174; Prider, 1941, p. 48; Davis, 1944, p. 456) and require mt further 
ennside-redion liere. 
(4) 77/c basic: dffkcs also have a general N.X.E. ti'end following the 
structure of the* gj'aniles. There apiiears to be erne age* eiuly represented 
and all Ihe speeimens t'xamineel preive to he epklioril(>s e-onsisting esseitlinliy 
of (ibnms uralite ( re*crys(allised around the* horeh'rs of the aggregates lei 
j)rismalic hlne-gret'u hornblende) and plagioclase witli smoky appearance. 
Relie'ts of ophitic ie'xtnrt* amt the presence of (*nel-phase micropeginatitc 
point to a close re'laliouship of these epielieirites with Ihe quartz dnierite's 
in other meu'e distant parts eif the Darling Range*. This matter has been 
dealt witli more fully in a pi’evious paper (Prider, 1948, pp. 4.4-S4). 
Tlie* ejiidiorites liave b<*en (|uai‘j'i(*d at Stathams for re>ad metal and 
concrete aggregates. In the exiiosures in the (]uarry basic ]iegmatile segrega- 
tions may eiccasionally he found anel the ocenrrene'e of stilhile ha-5 been re- 
cordeel by Simpson (1910, p. .'id and 1931, p. 36) from zeolite-calcite veins 
at the edges and also in the ce*ntre of tlte main dyke in Statham's (Jnarry. 
C. TITK T.ATKR ROCKS. 
The Later Rock< include the ferruginous sandstones and conglomerates, 
the high- and leiw-level laterites and the yellow sands the sanelplain forin. 
ing rn apron in front of the scarp. 
