The Contact Between the Granitic Kocks and the Caedijp Series 
AT Armadale. 27 
5 .— THE CONTACT BETWEEN THE GRANITIC ROCKS 
AND THE CARDUP SERIES AT ARMADALE. 
By Rex T. Prider, Ph.D., B.Sc., F.G.S. 
Read 13th August, 1940; Published 28th November, 1941. 
CONTENTS. Page 
I. Introduction . . . . . . • . . . • • • • • • 
II. Geology . . . . . . . . • ■ • ■ • • ■ • • • ^9 
(1) The held distribution and age relations of the rocks 29 
(2) The geological structure . . - - ■ - • • • ■ 31 
III. Petrology . * . . ■ - • • • • • • • ■ ■ 34 
(A) The older hybrid gneisses and the associated xenoliths 34 
(B) The younger granite (aplogranite) . . . . . . 37 
(C) The fine banded granitic gneisses . . . . . . • • 37 
(D) The Cardup Series . . . . . . - ■ ■ ■ - ■ 38 
(i) The sandstones . . . . • . ■ • • • 38 
(ii) The slates . . . . . . . . ■ • . ■ 38 
(iii) Contact nietamorphism of the sediments . . 40 
(E) The basic intrnsive rocks of post Cardup age . . • ■ 43 
(F) The quartz veins . . . . . . ■ ■ - • ■ ■ 48 
IV. Conclusions . . . . . . - . ■ • ■ ■ ■ ■ ■ • 
(a) The age of the Cardup Series . . . . . . - - 51 
(b) The Barling ^ ' Fault Scarp .. .. .. .. 52 
(c) Geological history of the Area . . . . . . - ■ 52 
V. Acknowledgments . . . . . . . . - ■ ■ • - • 53 
VI. List of References . . • • ■ . ■ - • • • ■ 53 
I.— INTRODUCTION. 
The Darling Scarp (Jutson, 1934, p. 84) is a prominent physiographic 
feature of the country near Perth. Tt forms the western edge of the Western 
Australian Pre-Cambrian plateau, which stands about 1,000 feet above sea 
level, and which is made np mainly of granitic roc*ks with later doleritie 
intrusions. West from this scarp and extending to the coast is a compara- 
tively flat coastal plain underlain by Cainozoic and Recent sediments and 
Bordered along the coast by Recent sand dunes (Clarke, 1926). 
On the western face of the scarp a series of steeply dipping slaty 
sediments Avhich form a narrow band beUveen the granitic rocks and the 
younger horizontal sediments of the coastal pdain is developed in a number 
of places extending from Gosnells and Kelmscott in the north to at least 
as far south as Mundijong (Honman, 1912 and Esson, 1927). These slaty 
sediments have l)een referred to as the Cardup Series (Clarke, 1930, table, 
pi. 187) and they are considered by both Clai*ke (loc. eit.) and Forman (1937, 
p. xxiv.-xxv.) to he contemporaneous with the Jinpierding Series of "V ilgarn 
(early Pre-Cambrian) age and therefore older than the granites and granitic 
ggieisses of the Darling Range. Forman (1937, p. xxiv.) says that the 
structures in the Cardup Series 1x4 ween Kelmscott and Miindi,iong confoini 
to the local structures in the adjoining gneisses and suggests that the gneisses 
ure, in part, of the same age as the Cardup Series and owe their origin to 
