199 
(Lower Silurian) Series in the Cambrian division, viz., in the 
Finke Gorge set of rocks, commonly called the South MacDon- 
nells. If 1 am not mistaken, some part of the Walker’s Creek 
Series (Devonian ?) may be found there in places as well. He 
fails to detect any unconformability between the Walker’s Creek 
Series and the Mareeno Bluff Series. He does not discriminate 
the one from the other, and, what is more serious, states that the 
fossils of Lower Silurian age that have been found in the district 
at such places as Mareeno Bluff, heads of the Walker and Palmer 
Creeks, Levi’s Range, and elsewhere have been found in the 
Upper Series. As a fact, they have only been found in the 
Middle or Mareeno Bluff Series. No fossils have as yet been 
found in the Upper or Walker’s Creek Series. 
In the paragraph “ Lower Silurian Rocks” the description and 
dip of the rocks occurring at the Lutheran Mission Station are 
correct, but to class them as part and parcel of the Lower Silurian 
Rocks is quite wrong. They belong to the Upper or Walker’s 
Creek Series, and not to the fossiliferous Lower Silurian Series, 
on which they rest unconformably. By failing to recognise this 
fact the paragraph is quite misleading. To discuss the errors 
Mr. Brown’s reading would lead to in interpreting such Ranges 
as the James’, Gardiner’s, Geo. Gill’s, and Levi’s is needless. Suf- 
fice it to say that the Upper or Walker’s Creek Series extends 
from north of the Mission Station, southwards (with one inter- 
ruption) to near Parkes’s Running Water, and east and west of 
that line for many miles; but south of the latter point Silurian 
and Cambrian rocks are more generally met with. 
Mr. Brown is in error in stating that the upper series forms 
the George Gill’s Range. That range is composed of Silurian 
Rocks in the main, but at the western end the Walker’s Creek 
Series are seen to overlie the Silurian Rocks unconformably. I 
make this latter statement with hesitation, because I had not 
time to verify my impressions as to the Devonian being there, 
but think I may without much risk venture so far. The southern 
portion of the James’ Ranges is composed chiefly of Silurian and 
Cambrian, not of the Walker’s Creek Series of rocks. Until 
Ooraminna Cliff is proven to belong to the Walker’s Creek Series 
it is better, in my opinion, not to connect the Walker’s Creek 
(Devonian *?) Series and the Ooraminna Cliff Rocks together, be- 
cause the Ooraminna Sandstone may turn out to be Silurian, and 
not, as has been supposed, of Devonian (?) age. There is a resem- 
blance in the lithological character and in the bold headlands, 
which is a characteristic of both the Upper or Walker’s Creek 
Series (Devonian?) and the Lower Silurian or Mareeno Bluff 
Series, and I have no doubt it was this striking similarity that 
led Mr. Brown into error. 
