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NOTES ON THE SEDIMENTARY ROCKS IN THE 
MACDONNELL AND JAMES RANGES. 
By CHARLES CHEWINGS, Ph. D., F.G.S. 
[Read June 5, 1894.] 
The object of the present paper is to point out, what I believe 
to be, an error the Government Geologist, Mr. H. Y. L. Brown, 
has made in the reading of the Sedimentary Rocks composing 
the MacDonnell and the James Ranges ; the area lying princip- 
ally within the watershed of the Finke River and its tributaries. 
I refer to Mr. Brown’s report to the Commissioner of Crown 
Lands, 1892, and entitled “Further Geological Examination of 
Leigh’s Creek and Hergott Districts, &c.” (Page 7, with ideal 
section). 
The stratigraphy of the MacDonnell and Ranges lying to the 
south has already received some attention, but its importance 
has not been so generally realised as perhaps it warrants. The 
time has arrived for definitely fixing on the most typical areas of 
exposures and development for purposes of reference ; and I will 
endeavor to indicate the best as known to me, and then state 
very briefly where I believe Mr. Brown is in error. 
Founpation Rocks (Archean of Brown). 
The most typical area is the north side of the MacDonnell 
Range. These rocks are composed of gneisses, various schists, 
dynamometamorphic granite, crystalline limestone, &c.; generally 
disposed at steep angles, and over large areas are quite vertical. 
Into this series granite and diorite, &c., have been intruded. 
Strike east and west. . 
GLEN HELEN Series (Cambrian and Pre-Cambrian [*}). 
The valley in which Glen Helen Station stands is a good 
typical area; it is situated in the MacDonnell Ranges, at the 
head of the Finke River. The principal rocks are quartzite, 
blue crystalline limestones, dolomite, and clay, slate, &c., usually 
with a dip of 70° to 90°. Quartzite is the lowest stratum, and 
rests unconformably on the ‘“ Foundation Rocks.” These are 
found largely developed in the so-called South MacDonnells, and 
in other ranges, and they rise through the eroded Lower Silurian 
anticlinals in several places, e.g., on the Petermann Creek. 
These rocks are generally seen to be nearly or quite vertically 
disposed, but are not always so. Strike generally east and 
west. In the quartzites on the north side of Mareeno Bluff 
