HORN EXPEDITION — SUMMARY. 107 



of 1330 fft't ;iljovL'. s(_';i level may bi; taken as an uxaiiiplc. Bcueatli the Desert 

 SandstuiH^ eapjiin^ (eighteen fe(^t) are purple and grey shale twenty-two feet ; red 

 shale, forty feet and bencatli them an unknown thickness of yellow and grey shale. 



Pa.ssing nurtliwards towards the James llange, that is towards the old shuri^ 

 line uf the Cietaceous sea, the shales and clays are replaced as might have been 

 expected by sanilstone. " For the most part the stratification of the Upper 

 Cretaceous is apparently horizontal, though slight undulations of far reaching 

 extension prevail in th(^ ncirthern area occupied by the rocks."* 



With regard to the supply of Artesian water in the Cretaceous area which 

 has beiiu dealt with in important papers by Messrs. Etheridge,t JackJ and Browni; 

 the conclusion is readied owing to the "far northerly extension of the Cretaci^ous 

 rocks and tlu^ replacement of the prevailing ai'gillaceous condition by sandy strata 

 towards the northern Ixmndary" that it is probaljle that in the district traversed 

 "the source is, after all, of local origin." The Finke in its course from Henbury 

 to Crown Point and the Goyder and Lilla Creeks near their sources flow approxi- 

 mately along the line of juncti(jn cf the sandy Cretaceous and the impermeable 

 Ordovician limestones. In this way, especially as the Cretaceous beds have a 

 slight southerly dip the Hood waters may be absorbed and carried down to 

 considei'able depths in the depressed Lake Eyre basin and so provide the supply 

 oljtained by such bores as those at Oodnadatta., Hergott and 8trangways. 



(4) Desert Saiidstone or Siipni-Cretaceous. 



The greatest thickness of this formation as seen at Crown Point was estimated 

 at lifty feet. It consists there of "sharp grains of glassy cjuartz, varying nuich in 

 size, cemented by opa(jue-white highly siliceous matter and more or less staincil red 

 by oxide of iron."|| The identity of the formation over wide areas of the interior 

 from South Australia to Queensland has previously been clearly pointed out by 

 Messrs. Jack and Etheridge^ and Mr. H. Y. L. Brown.** By Messrs. Jack and 

 Etheridge the Rolling Downs are regarded as Lower Cretaceous, the Desert Sand- 

 stones as Upper Cretaceous. Mr. Brown on the other hand describing the 

 Cretaceous strata betw(!en the 139th parallel and the western Ijouiulary line of 

 Queensland from Lat. 26 to Lat. 32 8., says, as quoted by Messrs. Jack and 



Geoloy-.V, Part III,, jp. 01. 

 t \ Geolofjy of l^iiifcnsUiinl, uk'., lip. \\\-\%i. 

 X Aust. Ass. Adv. Sci., Brisbaiic, vul vi., IS'Jo, Ji. o30, 

 § Aust. Assoc. Ailv. Sci., Syilncy, vol. i., 1S7S, ]). 2 13. 

 II Gcoloyy, Part III., ]). 05. 



ir Gcolo^'y of Q.uucnsland, etc. Tlic Desert Sandstone Kuririatiun, \\. jll. 

 *• Report of Gov. Gcolo^'ist. Adelaide, ISSU, etc. 



