253 
THE GEOLOGY OF THE MOUNT LOFTY RANGES. 
PART l.— THE COASTAL DISTRICT. 
By Warrer Howcury, F.G.S., Lecturer in Geology and 
Palæontology in the University of Adelaide. 
[Read September 6, 1904.] 
PLATES XXXVII. то XLIV. 
CONTENTS, 
PAGE 
I. Introduction _.... 64 på ". 56 253 
II. Order of Suecession— 259 
(A) Purple Slates... Fi T vi 260 
(B) Brighton Limestones and Siliceo-Calcareous 
Series di Er ІП 262 
(C) Tapley's Hill Clay Slates .. a 8 264 
III. The Field River Section ... AR 265 
IV. The Onkaparinga Section 3 qe 27; 269 
V. Southern Extension of the Calcareous Series (В) ... 278 
I. INTRODUCTION. 
The geological age and successional order of the rocks of 
the Mount Lofty Ranges have given rise to much discussion. 
The earliest observers, such as Jukes, Burr, Selwyn, and 
Others, were content to use some general terms for their 
designation, such as "primitive schists,” “primary,” or “lower 
palzeozoie," without risking any definite determination. 
Mr. A. R. C. Selwyn (at that time Government Geologist 
of Victoria) in 1859 made an eight weeks' geological tour 
of the country, extending from Cape Jervis to Mount Serle. 
In his official report to the South Australian Government, 
Selwyn refers the palæozoic rocks met with in his journey to 
three divisions, which he named respectively (a) first 
stage: (4) second stage; and (с) third stage. These he re- 
garded as probably distinct and unconformable, and with 
Some hesitation classed them as Cambrian and Silurian, or 
possibly going as high in the series as Devonian. 
Taking these three series in descending order, Selwyn 
defines their occurrence as follows: — 
"First.—Those beds which occupy, in great anticlinal and 
Synclinal undulations, the whole of the country north to 
Mount Serle, from a line drawn from the head of the Will- 
ochra north-easterly to the head of the Siccus River, consist- 
ing of: —1. The upper quartzose sandstone and quartz rock 
Series; which, commencing with the summit of Mount Re- 
markable, extends through all the peculiar flat-topped and 
tent-shaped hills west of Port Augusta, and forms generally 
