The Geology and Physiography of the Lawnswood Area. 
53 
A narrow strip of metasediments (mica schist and quartzite) out- 
crops ill the upper granite gneiss, at a distance varying from tive to 
12 chains from the upper (piartzite. Owing to the very highly weathered 
nature of its component rocks it is not certain whether this band is 
continuous, whether it is a series of elongated lenticular xenoliths of the 
Jimperding Series, or whether it is an infold of the upper metasediments 
in the gneiss. Another narrow and discontinuous band, situated approxi- 
mately 40 chains east of Nunamullen lirook, dips 70° to the east in the 
south, ()0° to the west about a mile and a half north of l^awnswood, 
while in the vicinity of P.S. I'rig station there is an anomalous western 
sii'ike and a h)w dip to the south. 
As the sediments have been very highly metamorphosed causing com- 
l>lete re(-r\ ^tallisation, original features, such as graded bedding and 
ripple marks, have been almost completely obliterated. Prider (23, t>- 8")? 
mention-^ that, in the Toodyay Area there are some obscure current bed- 
ding structures but no certain interpretation of these was possible. Drag 
folding was not observed in this area, hut Prider (23, j). 87) has found 
drag fold-, in tlie lower quartzites of the Toodyay Area, approximately one 
mile south (if W.B, Trig station, which indicate overturning in that locality. 
Minor cross folds are indicated by the variable pitch of well developed 
h- liueations in the quartzites. 
2. Granitic Gneiss. 
A diii-k, concordant, grajiilic gneiss body ota upies most of the central 
portion of the Area corrcsj'.oncing with a mature ^ alley about three, miles 
wide (see Blate 1). This is correlated with the Id'per Gneiss of the Toodyay 
Area. In llie north-east corner of the Area, a second concordant granitic 
gneiss oc:-urs, which corresjumds to the Lower Gneiss of Toodyay. 
Although ptygmatic folding is occasionally developed in the gneiss, as 
is well .-e(m in llie outcrops in the bed of Silencer's Brook at ('lackline, 
generally file j)laty paralleli'in of the gneiss conform^ closely in dip and 
strike with the as.soidatcd metasediments. Xo work was done on linear 
parallelism of the gneiss. 
3. Intrusive Granite. 
Granitt' invades tlio Jimperding Series in tbe south-east corner of the 
Area and continues immediately south and west of Clackline. Probably 
the boundary of this Younger Gratiile and the Jiinjicrding Series turns north 
within a mile west of Clackline and thence runs north to the south-west 
corner of the Toodyay Area (see text iig. 3). 
The intrusive granite ap])cars massive in the field except near the con- 
tact with the metasediments south and west of Claekline, where the gneiss- 
like handing of the rock is due possibly to platy how structures developing 
near the contact with the country rocks 
There are two varieties of gi’anite, a ]iorphvritic and an eouigTaiiular. 
The porphyj'itic is eonfined to the south-east part of the Area, and passes in 
a distance of a chain or two into the etpiigrauiihu’ variety. 1 ho equigranular 
granite occiqiies the south-central portion of the Area and extends at least 
a mile Avest of Claekline. The por])liyritic granite passes into the granitic 
gneiss very abruptly, but the transition from cqnigranular granite into 
granitic gneiss is very gradual. 
