198 
Pass annelide burrows are numerous. These rocks may be Cam- 
brian, and if so, these are the only traces of organic remains yet 
discovered in this series. 
Mareeno Buiurr Series (Lower Silurian in part). 
A good typical section and area occurs at Mareeno Bluff, in the 
western part of the South MacDonnells, but these rocks have a 
large development in the James’, Gardiner’s, Geo. Gill’s, Levi's, 
and other Ranges, and good typical areas exist at the heads of 
the Walker and Petermann Creeks and elsewhere. This series is 
composed from below upwards of red shale, then black and green 
shale, with fossiliferous bands of limestone, which, according to 
Etheridge, are of Lower Silurian age. This is conformably fol- 
lowed by a great development of red and white sandstones, with 
quartzite bands in places. The limestones and shales vary in 
thickness in different localities. This is, perhaps, the most im- 
portant and widespread series of Paleozoic rocks in Central Aus- 
tralia. At Mount Palmer, in the Western MacDonnell, and on 
many of the eroded Silurian anticlinals, the unconformability of 
this series to the ‘Glen Helen Series” is apparent, and generally 
very marked. The strike is generally east and west, and the 
dip varies from 0° to 90°. 
WaALKER’s CREEK SERIES (Devonian [?)). 
This series of rocks has excellent typical sections at several 
places along the course of the Walker Creek, west of the Tempe 
Downs Station, in the James Ranges. The formation is generally 
confined, as it is at this place, within the synclinal folds of the 
Silurian Rocks (Mareeno Bluff Series), and would have long since 
been eroded quite away in many places but for the protection the 
Silurian and Cambrian trough edges have afforded ; as it is, these 
rocks have been worn back for long distances from the older 
rocks. This Walker’s Creek Series is composed of red mudstone 
and red and green shales, conformably overlaid by ferruginous 
sandstone, each being several hundreds of feet thick. The un- 
conformability of this series to the Mareeno Bluff Series is very 
marked, as may be seen in many places along the Walker, as 
stated above. These rocks are sometimes seen in isolated patches 
resting unconformably on the highly or vertically inclined ridges 
of the Silurian and Cambrian Series. 
CONCLUSIONS. 
I agree with Mr. Brown in the what he terms the Archean 
Rocks, they are the foundation rocks of Central Australia ; but 
instead of three series of Palsozoic Rocks, he only admits two. 
He includes part of, if not the whole of, the Mareeno Bluff 
