The CJeology of the Darling Scarp at Ridge Hill. 
105 
5.— THE GEOLOGY OF THE DARLING SCARP AT 
RIDGE HILL 
By 
Rex T. Prider 
(Department of Geology, University of Western Australia). 
Read: 1 1th June, 194(5. 
CONTENTS. Page. 
I. Introduction 105 
II. Physiography 106 
III. Geology 
A. Field distribution and relationships of the rocks ... ... 108 
B. The PreJ-arabrian rocks 
J. The granites ... ... ... ... ... ... 109 
2. Sericite schists ... ... ... ... ... ... 110 
3. Quartz veins ... ... ... ... ... ... 110 
4. Basic dykes ... ... ... ... ... ... 110 
C. The later rock.s 
1 . The ferruginous sandstone series 
(i) Conglomerates ... ... ... ... ... HI 
(ii) Sandstones ... ... ... ... ... 112 
2. Laterites 
(i) The high-level laterites ... ... ... 116 
hi) The low-level laterites... ... ... ... H7 
3. The yellow sands ... ... ... ... ... H8 
IV. Summary and Conclusion.s ... ... ... ... ... ••• 127 
V. Acknowledgments 128 
VI. List of References (Jited 129 
T. INTRODUCTION. 
The Darling tSearj) whi<‘li 1‘onns the western edge of the Darling Plateau 
has generally been j’egarded as a fault scarp ( Sainl-Sinith, 1912, p. 70; Jut- 
son, 1912, p. 149 and 1934, |l 8(5) but cdoser (‘xamination of some critical 
areas in recent years tlu’ows some doubt on this hy])othesis. Thus the slaty 
rocks at Armadale considered by Saint-Smith (1912, (). 71) to bo evidence 
of the Darling Fault have, on closer examination (Prider, 1941, p. 52), 
yielded evidence that the earth movements recorded in these rocUs are exactly 
the opposite of that required by the Darling ^‘F^auU”. A characteristic 
feature of the Darling Scarp in the vicinity of Perth is a laterite-covered 
shelf at an elevation of approximately 200 feet above sea-level (AAoolnough, 
1920, p. 16) which Woolnough calls the RiJge Hill Shelf and which he 
considers is a step-faulted portion of the high- level laterite (Darling) 
141G0/2/48 — 630 
