NATURIi 



[May 2, 1S95 



• ,u,iri/ Micti^ ii.ni. i>i>.ii traced across the dyke towithiiian inch of | 

 thcslatf which cnclnsfsil. Iml thcrt- is notraceof any varialion in 1 

 ihc sciiiincntarj' slalv ojiixisitc the tnd of Ihi- quart/. A small 

 watercourse cuts through the dyke and ex|xises arsenical pyrites j 

 and iron oxide, with small |mrlicUs of gold. A more accessible 

 instance of intrusive granite is ex|>osc-<l in the cutting for the 

 hywash of the Bri.sliane Waterworks, at Enoggera, where the 

 igneous rock has intruded l)etween the strata of the slate. 



Per.M€>-<akhomikrois Rocks. 

 From the middle to the close of the I'ermo-carboniferous period 

 the dry land teemetl with vegetation, of which the Lepido- 

 'lendron was a conspicutms ty|H;, along the eastern division, for 

 ihough this plant was most aliundant in Queensland, it is also 

 I'ound in \ictoria. and on the Philips River, in West Australia, 

 where the later I'enno-carlmniferous rt>cks are found on the south 

 coast, extending from .Mbany eastward to Israelite Bay, forming 

 the .Stirling Range., with an elevation of 3CXX) feet, the Mounts 

 liarren. and Russell Range. The age of these rocks is 

 determined by the occurrence i>f large fragments of cartxjnised 

 vegetation, the asjiect of which closely resemble I,epidoden- 

 dron stems. This formation is limited to the coast district. 

 as, at a distance of fifty miles inland, the granitic plateau is 

 reached with its [lartial coK)Uring of Devonian slates. On the 

 northern coast the rermo-carbonifcrous rocks are de\elo|>ed in 

 the valley of the \'ictoria River for a hundred miles from the 

 sea. Also im the Kimlierley goldfield, to the smith-wesl of 

 Victoriii. 



(;KO(.;RAflllrAI. FKATl'Rt;S. 



The geographical features of this jxjriod appear.' to ha\e l)een 

 a continent, somewhat similar in form to that of the present 

 Australia. There was an elevated range along the Ciist coast 

 «hich attracted moisture, .tnd a climate favourable to vegetation, 

 .ind also by rapid lUgradation of its rixrks supplied suitable soil 

 :or tropical gci>wth. The central interior was not favoured b\ 

 -uch a climate, and there are few traces of cither ileiX)sil or 

 denudation. Thi- western interior enjoyed a moderate rainfall. | 

 .ind the detritus was carrie<l down ti>wards the north and .south 



• ■t>asts, where it was <le|K>.sited in regioiis where thecarlioniferous 

 Hi>ra flourished, though not to the sime degree as in East 

 Australia, where it. laid the foundation of the great ctxilfields of 

 \ew .South Wales and Queensland. 



KURIIIKR El.KVATIO.S Ol- CoNTINKNf. 

 .Vbout the end 'if the I'aheozoic or the, commencement of the 

 Mesoy-oic ])eriiKls there a|>|>ears to have l>een a further elevation 

 of the continent. es|>ecially in the eastern |xirl, for ihough in 

 many places the ilejiosits of the strata .show little interruption, 

 in others there Ilis lieen considerable disturbance and unc<m- 

 fomiity of succession, with indications of an increase in the 

 elevation of the laiul. which, with a contingent incrc-ise of rain- 

 fall, account.^ for the luxuriant growth of the carlKinaceous flora 

 and its extension much further to the west. The artesian Itores 

 which have lieen m.ide show that the crel.aceous be<ls rest on the 

 larbonaceous at a depth of 2000 feel In-'low the present ocean 

 level, and the fre.sh-water lieds of the ct>al series are not less 

 than 3000 feet in thickness, showing that the terrestrial lexel of 

 the mountains has lieen decreased 5000 feet, or. in other words. 

 they were 5000 feet higher during the Mesozoic period. On Ihe 

 western coa.st the elevation is not so well defined, but the land 

 was at a grc-ater height atmve the ocean than at present, as 

 iragments of coal and ils acc€>m|>an)-ing minerals have, been 

 w.isheil up from the deep sea. and may lie founil endiedded in 

 the Tertiary liniolones of Ihe roast. Tlurc is thus proof thai 

 in the weslcir,c>t ihe land extended further, ami wa- iiivere<l with 

 \u>lr.-ilian fresh-water flora of thecoal period : but this area is now 

 ■•ulimerged, and, taking into con.sideratiim the great depth of 

 the ocean on this coasf, Ihe height of the land nnist have 

 exceeded ils present level by a thousand feel. ICxamining the 

 ■ und the present .Australian coast, even 5000 feet 

 iliderence in the limits of the west, .xiuth, and 



i.>: but on the north and exsl the land would 



extend to the < ireil liarrier Keef. I'apua would have lieen 

 annexed, and even the .\rufura Sea and l.sland of Timor might 

 have been lirought nilhiii Ihe limits of Terra Amtratii. 



\ KOKlAlniN ol- All.><rKAI.IA. 



The mountain raiigcH of the cost coast would lie connected 

 with ihoK of I'apua and form a magnificent series of summits of 

 10.000 feet elevation, a configuration that must have arrested 



the moisture from the Pacific Ocean, and resulted in a moist 

 tropical climate, well calculated to supjxirt the luxuriant growth 

 of the vc-geUition of the coal jK-riod so far as East .\ustnilia was 

 aflected, though it might also have had the effc-ct of rendering 

 the climate of Central and West Australia .so dry .ts to render 

 the land a de-sert iluring the continuance of this carlHinaceous 

 jieriod. East Australia has thus, on its lower levels, accumulated 

 stores of fuel for use in ages long suliictiuent. The luxuriant 

 vegetation necessar) to the production of coal was limited to 

 the are-a east tif the I40lh meridian, except in a pcirtitni of South 

 -Vustralia, which seems to have been favoured by the overflow of 

 some large rivers draining the western slopes of thetireat Range, 

 and hatl their outlet through Spencer's (iulf. The vegetation 

 of Au.stralia at this period, however well adajned for the forma- 

 tion of coal de]X)sits. was not such as in the jircsent wtiuld 

 be suitable for the maintenance of mammalian life, as it 

 consisted of ferns, cycadea. palms, and pine-trees, of 

 which only the Araiicaria Jiid'u<iUii has left a living 

 repre.sentalive. and ils silicified wood from the coal formation 

 presents exactly the s;\me structure as the tree now gr<iw ing on 

 the ranges. Australian geography underwent little change 

 during the Meso/.oic period, but at tlu- comniencemeiil of the 

 Cretaceous a general .subsidence of the whole continent began. 

 The ctial deposits ceased, and a fresh-walcr deposit known as 

 the Rolling Downs formalion accumulated, the constituents 

 lieing soft .shales, which in the earlier period supported a growth 

 of ferns and pine limber. The land continued to sub.side until 

 the ocean invaded a large portion of the lower lands, but onl) 

 as a shallow sea. or jxissibly in the form of estuaries, as the 

 fresh-water vegetation apjKars intercalatc<l witli marine lime- 

 stones containing .Vmmonitesand other mollusca of the Cretaceous 

 epoch. 



Till; Ck]-;ta( liors I'l-.Kiiin. 



The depression during the Cretaceous period nnist liave Ixjeiv 



gradual and of long continuance. The ocean apiKirently first 



covered the laiul near the C>real .\ustralian Bight on the south, 



I and Arnheini's Land on the north, as in each of these localities 



I. there arc extensive deposits of thick bedded limestones, which 



I may have continuity .across the continent under cover of the 



ferruginous s,and.stones of the latter jiart of ihe eixich. On the 



east coast the ocean rose from 100 feet lo 200 feel above its 



present level in (^Hieensland. as the margin of the Cretaceous 



rocks is visible clo.se to Soulh Brisbane, an<l there is a bell along 



the coa.sl from Point Danger to Cdadstone. I'urther north there 



are extensive ]iatches of Desert .Sandstone belonging lo this 



period, though Ihe designation .seems lo have been applied to 



two distinct beds of s;uidslone. one bclimging to the clo.se of the 



Mesozoic, and the other lo the last part of the Cret.aceous. 



CiRKAT Dkprkssion anh Erii'1 IONS. 



lltimalely the dry land was re<luced to the eastern ranges. 

 fromCa]K- I lowe northerly Ui lal. 15° : the eastern side nearly the 

 Siime as the present coasl-line, and extending from loo to 300- 

 miles westerly, while Ihe Mount l.ofty Range in Soulh .Australia 

 existed as an island. This great depicssion was .iccomiianied by 

 dislocations of .strata and also ihe eruption of porphyritic in;vsses, 

 the age of these eruptions being easily determined as they rest 

 on the Ipswich coal strata. .\l .Mount l-linders the liase of the 

 mounlain consists of coal shales with abundanl imjires-sions of 

 l\<opleris. while Ihere is a more inslruciive instance near Tcviol 

 Hrook, where in a <leep ravine Ihere is a dyke of porphyry 

 culling through a lied of carlKinaceous shale with Picoptcris and 

 the silicifieil stems of pine-trees embedded. The dyke itself is 

 dark-coiiiured and highly crystalline, but where il spreads out 

 into a flat .sheet on the top of the hill il assumes the same 

 appearance as ihe lighl-coloured |iorphyry of Bri.slane. This 

 ixirphyry forms .the Class-house Mountains, which are so con- 

 .spicvuius from the entrance of Moreton Bay, and also Mounts 

 Warning, Leslie, Mar<Kin, and Barney. 



The central and western parts of the continent were almost 

 entirelv submerged in ihe ocean, but not to any great deplh. as 

 the higher granite peaks of the north-west do not show traces ol 

 .submergence, though the sedimentary deposits approach closely 

 l<i their liiLses. The Stirling and Mount Barren Ranges on Ihe 

 soulh coa-st were only partially covered, as ihere is an aniienl 

 sea lieach on Ihe south side of 'middle .Mounl Barren, about 300 

 feel aUive Ihe present sea-level. The interior tableland, though 

 now of greater altitude than .Mount Harreii, was .subnieiged, as 

 evidenceil by the extension over the whole of ihe rest of West 

 Australia of soft sandstones and clnystones in which salt and 



NO. I V?l. \''"-. .S2 I 



