nOKN EXPEDITION — GENERAL GEOLOGY. 61 



In 1891 Mr. Clicwings (xi., p. 2^)2), classc-d tlii.s cungloiiierato witli "Mudstone 

 and tli(! Oi)r-aiiiiiiiia Saiidstdiic " as Dmoiiiau (?) The Ooraniiiuia Saiulstoiit', as 

 iiicutioued c'lsewlici'o, we hclicvo to Ijeluiii;' to tlu^ ( )i-(lo\'ician System, wlicrras it is 

 quite certain that tiic conglomerate must be younger. 



During a trij) from tlu^ Lutlieran Mission Station, on tlie Finke, noitiiwards 

 via EUery Cretsk to the McI)onnell Ranges, an excellent section of this conglom- 

 erate was examined. Four miles N. 60^ E. from the Mission Station loose peljbles, 

 that did not appear t') be deri\ed froni a recent river gra\('], wei'e observed on the 

 surface of low circular hills. Two miU^s farther north a well had been sunk in 

 micaceous conglomeratic sandstone. Twelve niih^s N. 5G" E. from the Mission 

 Station the track crosse<l Ellery Creek, and here the conglomeratic .sandstone was 

 tirst seen /// si^i/, its dip lieing lo' nearly due south. Eurthei' to the N.E. the 

 conglomerate, alternating with pebbly saiulstone, dips at 14' S.S.W., the former 

 being very coarse in places, some of the jjebbles being as nuich as one to two feet 

 in diameter. Here some j>ebbles ^\■ere collected, which i)ro\ed on examination to 

 have been derived innn graintes, gneisses and schists of \arious kinds, with also a 

 few (piartzite pel)bles. Northwards the angle of inclination of the beds gradually 

 increases, as the- following figures show: — l)ip whcue lirst observed (at "Sheep 

 Camp"), 15"; at 3 miles, "JO ; at li|, 30'; at 6, 4J" ; at 6|, 49"'; at 7;^, 60'; 

 at 8, 60 = . 



At eight miles from the locality, where the conglomerate was tirst observed, 

 the dip had gradually increased to 60° ; it was at this place that pebbles of red 

 limestone were obtaine(l from the conglom<'r;i te, wliicli contained the following 

 Orilovician fossils ■.--.litinoiCnn tatci, rahrarca 7Vti//li\ 0/i/iis dic/idtdiiiah's, frag- 

 ments of trilobites. Undei'lying this cr)ngloiuerate is sandstoiu' dipj)ing 61° 

 south, followed by ([uartzites and limestones belonging to the (Jidovician Systen), 

 which gradually increase in dip as they are traced to the noi-th. An examination 

 of the pebbh^s, obtained from tln^ longlonieratt', reveals the fact that the lowest 

 strata which of course were deposited lirst, are almost entirely composed of 

 fragTiients derived from the ( )rdovician strata, such as sandstones, limestones and 

 (juartzites, while the topmost layer.s are very largely made up of pebV)les din-ived 

 from the Pre-Cand)rian rocks. These phenomena show that, when the lowest beds 

 were being deposited the liveis were eroding their valleys out of Ordovician strata, 

 but that, when the upjjermost beds weri' being laid down, the erosion had extended 

 to the undf^rlying Pre-Cand)rian rocks. The total thickness of this conglomerate 

 and cou'domeratic sandstoiu^ cannot be less than 7000 feet. 



