^)a,/t^mia S^o^^^'^'¥ o^ C/ceence<^ RECEIVED BY PURCHASE June 16, 194? Digitized by the Internet Archive in 2011 with funding from California Academy of Sciences Library http://www.archive.org/details/reportonworkofho03horn PART III, -GEOLOGY AND BOTANY. REPORT ON THE WORK :'..; ' '-^-- / / ^'^<*^vi^ OP THE HORN SCIENTIFIC EXPEDITION CENTRAL AUSTRALIA, PART lll.-GEOLOGY AND BOTANY. \ I / BALDWIN Sl'ICNCElt, .M.A., Professor of Bioloov ix the L'xiversity of Melboirne. Itontion DULAU AND CO., 37 SOHO SQUARE. illi'lbouriu 31 E L ^M L L E , ai U L L E N A N 1) S T. A I ) E MARCH, 1896. PRINTED BY FORD AND SON, CARLTON, MELBOntNE, LIBRARY ^^^ OF SCltH^ PART III.—GE0L(3GY AND BOTANY. TABLE OF CONTENTS. SECTION I.—PHYSICAL GF.OGRAPHY AND GEOLOGY. I'AGE PHYSICAL GEOURAPIIY JJy Protessor PtALPU Tatk and .J. A. AVatt, M.A., Il.Sc. ------ 1 GENERAL GEOLOGY - Py Piufcssor PtALi'U Tate and J. A. Watt, M.A., B.8c. (Plates 1 and 2) - - - 2G L Pkevious Rkcoi£Ds and Rkfkuknces tu thk Litekatuue of THE Region --------- 2lJ 2. Pke-Cambrian - - - ----- - 33 3. Okdovician --------.. 46 4. Post-Ordovician Conglomerate ------ 60 5. Upper Cretaceous - 62 G. Desert Sandstone (Supka-Cretaceolh) ----- 65 7. Post-Cretaceous Phenomena ------ 68 8. Tertiary ...--... - 71 ECONOMIC GEOLOGY - Py J. A. Watt, M.A., P..Sc. - - - 76 PETROLOGY - - . By W^ F. Smeetii, M.A., A.R.S.M., and J. A. Watt, M.A., P.Sc. (Plates 1, 2, 3, 4) 82 PALEONTOLOGY' - - By Profcssur Ralph Tate (Plate-s 1, 2, 3) 97 SECTION II.—BOTANY. BOTANY - - - - By Pivjfcssor Ralph Tate, with an Appen- dix by J. H. Maiden, F.L.S. - - 171 1. The Larapintine Flora - 117 2. The Central Eremian Flora -...-- lyi Appendix. Notes on some Ve(;etaijle Emdations. By .J. H. Maiden, F.L.S. - 195 — PHYSICAL GEOGRAPHY. By PROFESSOR RALPH TATE mid J. A. WATT, B.Sc. Ill dealing with tlie sul))ect of tlie pliysical geography of Central Australia, it is necessary to mention that only a very general and brief outline will be given, as the space available does not permit of anything like a complete account. It will l)e dealt with under' the following heads : A—MOUNTAINS. 1. McDonnell Ranges. 2. James, Waterhouse, (ieorge Gill and Levi Ranges. 3. Cretaceous tabh^-topped hills, etc. 4. Ayers Rock and ]\Iount Olga. B.— RIVERS. 1. Finke Basin. {a) Nature and position of its watersheds. (/') Area of the Finke River Basin. 2. Finke River. {a) Tributaries of the Finke. (/') Length and rate of fall of the Fiid<e channel. (r) Nature of tlu' course and channel of the Finke. {d) Absence of surface running water. (e) Waterholes. (/) Rainfall in its relation to surface waters. C—GORGES AND GAPS. D.— LAKES. E.—CLAYPANS. F._STONY PLAINS. G.— SANDHILLS. HORN EXPEDITION—PHYSICAL GEOGRAPHY. A.—MOUNTAINS. In the consideration of the physical geograpliy of this country the mountain system should first demand our attention, as being of primary importance, for on it not only does the trend of the main valleys depend but also the size, number, and even the very existence of the rivers, by reason of its influence on the wind and rain. For the above reasons the McDonnell Ranges form the most important physiographic feature of Central Australia. Were it not for the presence of this chain of comparatively elevated land, with its important influence on the meteorology of the surrounding country, the greater part of the interior would re.semble a sterile desert, which is the actual condition of portions of the stony and sandy plains after a more than usually prolonged drought. The most important mountain i-ange within the area under consideration is doubtless that of the McDonnell, which represents the much -denuded crest of one of the highest folds, into which the crust of the earth within this area lias been thrown. In the crumpling oi tlie earth's crust the highest anticlines, being on the lines of maximum disturbance, usually have cores of plutonic rocks. Tliis seems to have been the case with a great portion of the McDonnell Ranges, subsequent movements having metamorphosed the originally plutonic rocks, thus causing doubt as to their eruptive origin. The mountain system of Central Australia does not consist alone of the McDonnell Ranges and tliose immediately associated with them to the north and north-east, as the Hart and Strangways Ranges, but includes also a number of parallel ranges lying to the south, such as the James, Waterhouse, George Gill, Levi, and Chandler Ranges, all representing the arches or troughs of the folds produced by earth movements in past geological time. Examples of ranges occupy- ing the troughs of the earth-folds are to be found in the case of the George Gill and Levi Range. In each of these ranges, which really are portions of one and the same range (their continuity being broken merely by the transverse valley of Trickett Creek, a trilmtary of Petermann Creek, the latter a branch of the Palmer), the rocks occupy a perfect synclinal trough, in which the sandstone dips from the north and south towards the centre of the range at an angle of from 10° to 20° The mountain system of Central Austi-alia may be conveniently treated in three divisions, the mountain ranges in each division for the most pai't comprising rocks of one and the same geological age, while they differ from those of the other divisions. ! IlUKX EXPEDITION PHYSICAL GEOGUAPIIY. 3 Thus (1) the McDoimell Ixan^es proper, as well as tlie Hart Range, are situated wlioUy, or nearly su, within the area occupied by inetamorphic rocks of presunialjly Pre-Cauibrian age ; wliile (2), the James, Waterhouse, George CJill, and Levi Ranges are wholly contained within the country occupied by Ordovician strata ; and lastly (3), tlie \o\v table-topped hills and groups of them, which one feels disinclined to dignify with the name of mountains and mountain ranges, are entirely formed of Ci'etaceous strata. Now, as each of these geological systems are repre- sented l)y rocks ditleiing in lithological character and structure, while they have suflcred diHeiently from tlie dynamic forces of nature, tlu^ physical features of the ranges occupied by strata of these different geological systems differ widely, a,nd will therefoi'e Ije described separately. (1) The McDonnell Ranges. Dealing with the features of the most important first, we find tliat the McDonnell Ranges trend in a neai'ly east and west direction for a distances of about 400 nules, and have a width varying from twenty to fifty miles, thus covering an area of more than 10,000 square miles. In the meridan of Alice Springs Telegraph Station, which is situated from three to four miles north of Heavitree Gap, where the River Todd breaks through the southern ))oundary (jf the ranges under consideration, they have a width of about twenty miles. Westerly fi-om this point they extend as a rugged main ridge, containing the most ele\atrd peaks, often capped by Ordovician quartzite, with a band of varying width of " jumbly " hills flanking this main ridge on each side. About the longi- tude of Mounts Liebig and Palmer (i.e., about 131' IT)') the range becomes much broken up. Easterly from Alici; S[)rings the range extends t(j about 136° east longitude; at 131" 10' it Ix'comes confluent with the south-east extension of Strangways Range, with wdncli it may be further eonsidcu-ed to be linked by the (ieorgina Range, aliout 131° 20'; while further east (about 135") it is joined by Hart Range. It may be said to extend approximately from tlx^ ]30tli to the 13(Uli meridian 7' 23° of east longitude, a distance of nearly 400 miles, and to lii^ between 23° and 35' south latitude, with an average width of lietween twenty to thirty miles. These ranges have a very irregular outline, and have no parallel hmgitudinal valleys; in fact, they pi'esent in no degree that uniformity of physical features produced by earth movements and meteoi'ic agencies, so familiar in the case of tin; Ordovician ranges. U 4 HORN EXPEDITION—PHYSICAL GEOGRAPHY. Tlie original stratification of the once sedimentary strata and the joints, that were perhaps present in the original granites, have played to all appearances no pait in the moulding of the present physical features out of the metamorphic rocks, the age of which is considered to be Pre-Canibrian. Rising abruptly out of the elevated area of the McDonnell Ranges, with no linear arrangement, but irregu- larly distributed, are a sei-ies of eminences, whose summits are in some cases, as in that of Belt Range and Mount Sender, capped by a northern extension of Ordovician quartzite. To the presence of this protective covering, which has effectually warded off' the levelling forces of nature from the underlying less weather-resisting metamorphic rocks, is probably due the comparative elevation of these peaks. Ranged in order west to east the altitudes above sea level of the chief peaks are as follows : —Mount Edward in Belt Range, 4649 feet ; Mount Heughlin, 4756 feet ; Mount Zeil, 4040 feet ; Mount Sender, 4496 feet ; and Mount Giles, 4210 feet. The average elevation of the surrounding country is over 2000 feet above sea level, so that these mountains are not so prominent as one might be inclined to imagine judging alone from their altitude above sea level. They are nearly all accessible, as the slopes are not usually very precipitous, except for example the Belt Range (Fig. 3). The movements of the earth's crust, to which these ranges bear witness, were to a gi'eat extent of Pre-Ordovician age, and were continued, though much diminished in intensity, down to Post-Cretaceous times.