266 
Brendan P. Thomson. 
Published information regarding* the geology of the area is as follows: — 
Honman (1912) traced outcrops of the Cardup sediments at man}' 
points along the front of the scarp. 
Esson (1922) examined the rocks of the Wongong dam site several 
miles east of the area, and in 1926 he reported on the silver lead deposit 
at Mundijong, several miles to the south, where part of the countrv in 
the vicinity of the deposit is made up of the Cardup series. 
Clarke (1920) mentioned the Carduj) series and published a map of 
Carduir 
Forman (lOdT, p. xxiv) considered that the Cardup series conformed to 
the local structure in the gneisses, which he suggested were derived from 
the sediments hy granitisation. 
Both Clarke and Forman correlated the Cardup series with the Jim- 
perding series of Yilgarn age, but Prider (1941) at Armadale has advanced 
strong evidence indicating that the Cardup series is younger than the 
granite and gneiss. 
The structure and relations of the gneisses to the Cardup series in 
the A\ ongong-Cardup area confirm the conclusions reached by Prider. 
The area was mapped during 1940 by the author working alone. It 
has been well subdivided by the Lands and Surveys Department, thus 
enabling detailed ma])ping to be done by pace and compass traverses. 
Form lines were drawn from spot heights obtained by aneroid barometer, 
with frequent checking on Byford Kail way Station and Wongong Siding. 
IT. PHYSIOGKAPHY. 
A. General Relief, 
The area may be considered to be made up of four physiographic units. 
1. The partly dissected and eroded block of the uplifted Darling 
Penei)lain (elevation 751) feet to 950 feet). This is mostly covered with 
laterite almve the 800 feet level. 
2. The scarf) front (elevation 400 feet to 750 feet) which is consider- 
ably indented and modified by the drainage system. 
3. The subdued “foothill’’ zone (elevation 250 feet to 400 feet), partly 
underlain by the Cardup series. This zone is discontinuous and it merges 
into the fourth unit. 
4. The sandy plain (elevation 200 feet to 250 feet) which slopes very 
gently to the west and forms the eastern border of the Rwan Coastal Plain. 
This subdivision agrees closely with that given by Woolnough (1918, 
p. 19), except in the treatment of the foothill zone. Woolnough’s Ridge 
Hill shelf at 200 feet elevation is not represented, except possibly by the 
small areas of low level laterite near the Beenyup and Cardup Brooks. 
B. Drainage. 
The Wongong, Beenyup and Cardup Brooks (the main streams in 
the area, see Plate T) are perennial. Features in common to these streams 
are: — the westerly direction of how; the young valleys; the west-north-west 
trend in the foothill zone. 
