32 HORN EXPEDITION — GENERAL GEOLOGY. 



sliale, and thin bands of limestone, also striking E. and W. . . The George 

 Gill and James Ranges are composed of these rocks. It is from these that Silurian 

 fossils were obtained." 



XIII. — TiETKENS, W. H., " Journal of the Central Australian Exploring 

 Expedition," Adelaide, 1892. In 1891 Mr. Tietkens, in command of a pro.specting 

 party, started from Alice Springs, skirting the north front of the McDonnell 

 Range to Mount Heuglin, thence to Mount Bonder and Glen Edith, and west- 

 ward beyond the West Australian boundary ; on his return route he examined 

 Mount Olga and Ayers Rock. A catalogue of the rock-specimens collected by 

 Tietkens is furnished by Mr. H. Y. L. Brown (Appendix, pp. 82-84), who also, by 

 sketch-.sections, shows the stratigraphical sti'ucture of the McDonnell Range west 

 of Mount Sonder, and of Mount Olga and Ayers Rock. Mount Sonder to 

 Mereenie Bluff, Mount Olga and Ayers Rock are coloured to represent " Meta- 

 morphic metal-bearing rocks " overlying granite. The quartose sandstone at Glen 

 Edith is referred to "Palaeozoic (Devonian ?}." 



XIV. — Brown, Henry Y. L., " Further Geological Examination of Leigh's 

 Creek and Hergott Districts," Pari. Paper, S.A., No. 2.3, 1892. The Government 

 Geologist made " a brief and rapid examination of the Finke River region in 

 September, 1890," and herein, under the title of "General Geology on the Finke 

 River," p. 7, he amends his previous outline description which is illustrated by 

 an ideal section from the McDonnell Range to Charlotte Waters. 



The fundamental rocks are classed as Archaean ; the quartzites, dolomites, 

 limestones, sandstone and .slate which crop-out in anticlinal arches on which the 

 succeeding formation rests apparently unconformably are classed as Cambrian. 

 The Post-Ordovician conglomerates at the Finke Gorge are here included. The 

 author records that the metamorphic granitic rocks dip under quartzite at Mount 

 Sonder and in a southerly direction are succeeded by highly inclined dolomites, etc. 



Lower Silurian. According to this author, the rocks of this age commence 

 in the range bounding the Missionary Plain on the south, and extend south to 

 Henbury and Ooraminna, the only distinction from the foregoing is " a less 

 disturbed rock-formation." 



XV. — Chewings, Ciiarle-s, " Notes on the Sedimentary Rocks in the 

 McDonnell and James Ranges," Trans. Roy. Soc. S.A., vol. xviii., pp. 197-199, 

 1894. This is, in part, a correction of previously published opinions (xi.) and a 

 criticism of Mr. Brown's classification (xii. and xiv.); his grouping is as follows : — 



