GEOLOGICAL MAP

Hokitika Guardian, 22 August 1932, Page 3

GEOLOGICAL MAP

OF AUSTRALIAN CONTINENT

BIG SCIENTIFIC WORE

A geological map of the CommOirt wealth of -Australia- with explanatory motes by -Sir Edgeworth David fills been published by the ComnmiweflKfi' Council for Scientific Research, .Sydney. The map, comprises .-tour sheets withj many sections l , pf , .explanatory motes. , ,

When Professor David retired from the Chair of Geology at Sydpey Uniyoiaity seven .years ago, he commence pd a work on the Geology of the Commonwealth at the instance of ’ the Federal. Government. Though this great and comprehensive work “has not /been completed,.,an essential part or it in tile foi;m of this detailed geological map has now. been, published;'and bears witness to the large amount of' wprk and compilation that has bben required.. Each State of , the Coin-' raonwealth has its ow r n geological survey and there is also a chair of geo 7 logy at the University in. every'State, It is| clear thalt -a- large number .'of geologists is at work and their efforts''' are largely supplemented by i'timsA' (mining geologists who .aie engaged, in the various metiU and ,coal? mines, 01 Australia. Tire w'Ork' of .all oF .these, has had to.be embodied, correlated and in parts reconciled in the prejparatibii of 'this w-ork. With the map t-heie is an explanatory pamphlet 176. pages in which’ makes it possible for ail to follow the stj-n.ctui;e..historical facte that are shown fij. lt. A.P many, as seventy-five (fifferent series of .deposits are shqwn, by ' the, colouring antf .'other indications, employegi.. -"i::-;-.,

’, A mei;e supeifficigl gjfuice shows . at,, once the . complexity pf the, easterp.margin of Lor here, a,Wr one .colour only, and, the rapid, change.,;.frqin our to colour show’s , fipw ! quiclj.ly.' thf;; rock types, and deposits .of ,pagt r age,:,, ; displace and suc,eed ( ,pne v . .anotiier. in comparatiyely short. ..distanee,a ; ;„ Yet, the sections, of ;! whicfi..,.,aev,eral,, are drawn on the ..maiginj. ; pf.,-th i e^. (: jmap, °l-sp show that., all except ifie / oldest, rock systems are here lyihg .imperatively simple : and. open -folds. >w- r ,

ROCKS OF HUGE" ANTIQUITY,

Leaving the easttqru margin ..of Australia and, travelling iat the hundred miles,..from the., the.central plains, .are .entered, .jeyel,,,surface cojnpared . ayitp th^mp/'e. mountainous < and dissected, ,of the eastern' 'jnargin.i' ..jT^yei}jpg, westward . .for nqai-ly, ,$)66. >wilpp stf , .country is merely undulating-uu.d 011 -tim . jurfacq,.rqcks 4 relatively;,small antiquity a!-U,contiiHiou,.s ; lyiound. .Outhe. westeru, of .gpn^enit,(UU4>morC|y particularly, in thg ~,.soli,th-.west,, pf'huge antiquity , the ireUof;.,l'- s ,§ip?plo.<: witlp'tkat of . tfie •;eartern .margin, ip a 5 This, rt/mfip,-----..with « ( ,tbe ... cxpjlauatoi’ji). pa mphlet, T show.s £ in -detail .;th.q j-f iasifc.jhi| , ..< tory of Australia from the beginnjnfv of time, which in. ,tfie geologicnj, sense? s is : some fhpusandsuf. millions of . years ago.,i/ight. up ,ip. the ;presep.t day;■ ; jspi-y. In such;,a,«briojFajbivi«w„ ns ,%4:his-j-tbsly more striking facts'-,pf this historyiibmr ly, can-1 be outlined. :.It cap-,be’ said; that, in,the pipsL ancient of days':yoliv Panic activity, as shown by the-pocks oi T the sopth-jvest .cornercwas, extepsiveyiprobably. violent. Then iE/is opwoiuf to note a glacial, ppndition pevailetl. though evidence-of this is ratheiufrag<. meptar-y. ‘ Then, but of cpp.rss.i'afte iime lapses I.of immense;length,' the; clfi ? male ,appears) to have been copal rpefs exended -..here-’-and-.th'ei'W' round the roast lands.: Of alEbf ,tll ; esU> vast periods ..there is ’little dr. -’po reti cord in M New' Zealand. -ui.-'-': a-ij

.! CHANGES IN CLIMATE' l*? ; CONDITIONS; r. - *; Some .five- hundred millions s,o£-yea;Bri ago. the record of .conditions-e^'shows I '. that in , the two , lands. .the I shorp ’line ■» and adj ( apent seq? w-ei-e inhabited, by identic, animal forips. ,)But. .this is, for a brief period only, v.and,, soon there is divergence again. After an Other lengthy.period an: jntepse glacia tion prevailed in Australia. it- n sheet from the south reached ,tfe&'*'*'s©ri level hear Melbourne find in several' cher places.. The glaciation was JonM though it waned and waxed time •- ami; again! The.,intervals ,oi genial climatic conditons produced swariip land's oi wdiich there grew abundant vegetation, the remains of which fpfhi thb ePfiseams of Newcastle. Af-fill this there is no record in , New-. '.Zpaladd. 'thPug' it seems thpt .thprei-Vlis*-'land 1 ' here. Again there, was a piifallelisiri-- and sandstones thick and Mextehsive tverc deposited in both Tan-ds?, fllloie o' Aiistialia are seen in the - "cliffy that border -Sydney harbour and lorm 7 rhe butting cliffs of the Blue MonWtaiiis In Nciv Zealand, the- ’■•ia.tfl stones oi

mas' . • yff- “T p 'Siflvrent nature and" "perhaps' origin are folded,. faulted and 'contotted': QPsr now constitute the Sdtithern' Alps 'ajtid the major mountain rations of New Zealand, including thO' rugged hills around Wellington.

While the whole of' Centr.ii' Austj alia was covered with a a shallow sea in times far later, New "Zealand perhaps grew to larger dimensions than ever before or since, arid' when once more the sea invaded the land our coal pleasures were formed arid new 1 for period after period sediments were deposited around the morint'iiC’i soil; pf the counl-y. but during these la e ages.we have' little or at the host fr: gmentary evidcuco of- Australian conditions. Afb tlie close of, this *. rertuify period shell^and other for ins cl marine'life had -almtfet their present variety and form. It Was then'that earth movements on a great scal y flirt lie ’elevated the mountain jha.ns, the rocks of which had been intensely crushed and folded and faulted long before. Probably at this time’, toe, some ‘of the striking features of the Australian Alps were developed.

SIGNS OF VOLCANIC ■' ACHY IT V.

There has not be n very extensive volcanic activi yin Austral ; n, thoughin many plates there are areas of volcanic rocks and striking-crags formed' of them,- while in-Victoria the ‘,l’asal-’ tic caves, near Melbourne are strikingly similar to- those near, Auckland.’ TriNew Zealand, as, is well known, the great volcanoes of the Ndith Island.were formed in the latest ge.d-'gmhf times, and probably many features of the rhyolite plateau from Taupo to Te Kuiti and Tauianga were developed. There was no, corresponding volcanic activity, in Australia.' , The construction of this inVp 'is ai noteworthy .contribution, to the scierir tific publications of the Commonwealth' and a tribute to the energy, and persistence of Professor . David, yvho h’s maintained all 1 the energy of ycu'.li .and combined it with the j dgment of maturity and wilh a fine mental balance. . These qualities have , enabled him to produce this map of the Commonwealth. ..■■■.