HOKN EXPEDITION — GENERAL GEOLOGY. 29 



extended northward to iiiflud(! Ch;uidlfi-'s Raiiije. The. Levi and George (Jill 

 Ranges ai'i! indicated as 'J"ei tiary, whilst the main portion of the Larapintine is 

 represented as granite and Newer Volcanic, except a small patch around Alice 

 Springs which is coloured as metaniorphic. 



Up to this date the wmk done has little claim to serious attention, as it 

 consists almost S(jlely of locality-records of a few kinds of rock-masses; no attempt 

 had yet lieen made to indicate their stratigraphical relationships, except in the 

 sole instance by Waterhouse, respecting the section at Polly (Springs. Some 

 excuse may therefore be found for the imperfection of the two geological maps 

 issued by the Victorian Government, the compilers of which had no other data 

 before them than such bare records as we have sketched herein. The information 

 had to be taken for what it was worth or wholly rejected ; hence the great blot of 

 Volcanic colouring on the later map, which error is traceable to Giles, and was 

 repeated and enlarged upon by Chewings. Their basalts ai'e the thick (juartzite 

 bands in the Larapintine Series, and perhaps also tiiose of the Pre-Canibrian. 



Vl [. — East, J. J., " On the Geological Structure and Physical Features of 

 Central Australia," Trans. Hoy. Soc. S. Aust., vol. xii., pp. 31-53, pi. iii., 1889 

 (Read 2iu\ April). — Being observations made along the Overland Telt^graph Line 

 from Lake Eyre to the McDonnell Range, and deals with the south and north-east 

 parts of the country tra\ersed by us. 



T(ipO}:;raphical FeatHri:s. — (1) " The Great Austral Plain " embraces the low- 

 level counti'y ab(jut Lake Eyre and the table-ttipj>ed hills and small table-lands 

 which arise fi'oni it — a vast regii>n of incoiisid(_'r;i,ble elevation. Sterile patches 

 covered with glazed subarigular st(jnes are herein called "gibbers." (2) "The 

 Terraces "' embrace the parallel raiiges of low altitude, .st^parated by broad valleys 

 or plains, connnencing near the juncti(jn of the Hugh and Finke Rivers. [The 

 term "terraces" is inapt]. (3) "The Great Central Plateau," the southern 

 boundary of which is the I\lcD(_)iuiell Range, whose furrowed southein face 

 developes the system of narrow ri<lges collectively known as the McDonnell 

 Ranges. [This descriiition, as also the stx-tion, pi. iii., fig. (J, is misleading, as the 

 general altitude of Rurt Plain, to the north, is (he same as that of the river- 

 valleys in the McDonnell Range]. 



Geological Slnidiire. — (1) Outliers of the Flinders Range from Finnis Springs 

 to Mount Dutton art^ classe(l as Aicluean |Our observations incline to the 

 opinion ihal, tliotigli (he Penkc Itaiige is <l(>ublies,sly Pre (Jambrian, yet the fissile 

 limestone and associated strata from tho Neales River to Mount Dutton i)elongs 



