42 



Around Lake Eyre the tops of some of the higher hills 

 may be composed of sandstones, etc., of Tertiary age. Reasons 

 for not extending these Tertiary cappings far in a northerly 

 direction are given later. 



Lower Cretaceous. 



Mr. Brown regards the blue shale of the Lake Eyre 

 artesian basin as Lower Cretaceous. Tate and Watt refer the 

 same to Upper Cretaceous. The delimitation of the northern 

 boundary is discussed in the following section. The writer 

 includes in this section many of the tops of the hills lying north 

 of Oodnadatta hitherto regarded as Tertiary. 



Jurassic ( ?). 



The valleys of the Finke and Hale rivers, so far as at 

 present known, furnish more evidence regarding the geological 

 history of Central Australia than any other part. In 1897 

 Mr. H. Y. L. Brown, then Government Geologist in South 

 Australia, published in a Parliamentary paper his revised 

 reading of the several rock systems occurring there, viz. : — 

 (1) Archaean gneiss, granite, etc.; (2) Cambrian; (3) Lower 

 Silurian; (4) Jurassic (?) ; (5) Lower Cretaceous; (6) Upper 

 Cretaceous or Tertiary; (7) Recent and Tertiary. Their 

 several equatorial extensions are delimitated in a section that 

 accompanies the report. The report, and also the section, 

 show clearly that Mr. Brown had altered his position in regard 

 to one of the important rock formations, viz., the Deep Well 

 and Ooraminna sandstones. Formerly he classed these as 

 Devonian ( ?), but herein they are, together with the Finke 

 River sandstones, as seen between Horseshoe Bend and Goyder 

 River, set down as Jurassic (?). To Mr. Brown belongs the 

 credit of first noting that the Finke River sandstones dip 

 south under the Cretaceous shales, and that they are "intake" 

 beds for the Lake Eyre artesian water supplies. The writer 

 agrees with the extension of the Finke River sandstones 

 northwards to Francis Well, but disagrees with the including 

 of the Deep Well and Ooraminna sandstones in that forma- 

 tion for reasons set out hereafter. The Cretaceous shale for- 

 mation is lithologically similar, from Lake Eyre to its 

 northern boundary, a few miles north of Charlotte Waters 

 Telegraph Station. As all observers are agreed on that 

 point, further comment is unnecessary as to its northern 

 margin. As to the age of the Finke River sandstones, Tate 

 and Watt held that the Upper Cretaceous persisted as far 

 north as Engoordina (Horseshoe Bend), and they mention 

 Chambers Pillar as the most conspicuous outlier. The writer 

 rejects Tate and Watt's reading of this formation. They 



