32 INALGUKAL ADDRESS. 



scientific value .... but it is of imrinsic valiie,asaffordingr 

 a clue to the unravelment of many highly complex biological 

 •problems relating to the distribution, evolution, and extinction of 

 organic forms.''*' 



Glaciation during Triasslc Period. — Another geological period 

 in Australia furnishes evidences of ice action, namely, that of the 

 " Hawkesbury sandstone," in the deposits of which occur, as first 

 indicated by Wilkinson in 1879,f " angular fragments of shale, 

 which have evidently been torn up by ice moving upon beds of 

 shale and mingled in an irregular manner with the drifted sand 

 which has formed the bed of sandstone immediately overlying the 

 shale bed." 



Glaciation in Pernio- Carhoniferuus Times. — Yet a third geolo- 

 gical period, that of the Permo-Carboniferous, has been interrogated 

 and has yielded evidences of glacial conditions on a large and far- 

 extending scale. The Bacchus Marsh sandstones and conglomerates 

 were referred by Selwyn, ;]: in 1861, to a period intermediate 

 between the Carboniferous and Permian, whilst the sandstones on 

 the evidence afforded by their plant remains were assigned by 

 McCoy to a Triassic age. From the character and* mode of arrange- 

 ment of the material of the Bacchus Marsh conglomerates, Selwyn§ 

 suggested transport by glacial action, though at that time grooved 

 or ice-scratched pebbles and rock surfaces had not been observed. 

 The occurrence of breccias and conglomerates in the Carboniferous 

 rocks of New South Wales subordinate to the " Upper Marine " 

 beds had been previously noted, though their significance had not 

 been indicated till Mr. T. Oldham || (Deputy-Superintendent of the 

 Geological Survey of India), when on a visit to Australia in 1885, 

 discovered some ice-scratched pebbles among them, near Branxton, 

 and correlated the conglomerates with the boulder group of Talchir 

 of India, the Ecca conglomerates of South Africa, and the glacial 

 conglomerates of Bacchus Marsh. Beds of similar aspect, and 

 indicating a similar mode of origin, have been described by Jack ^ 

 in the Bowen River coalfield, and by Hands*"* in the Gympie 

 series. The proof of the glacial origin of the Bacchus Marsh 

 conglomerates was indicated by Dunnf f , who reported that " a con- 

 glomerate with such characteristics suggests glacial action." The 



* Stirling, J., Roy. Soc. Vict., 1885. + Proc. Roy. Soc. \ S.W.. vol. xiii., p. 105, 18^0. 



t P:xliibition Essays, p. 182. \ Id., p. 183. 



II Records Geol. Surv. India, vol. xix., p. 43, 1886 ; Id., Gaol. Jtag., July, 1886. 



TI Report on Bowen River Coalfield, 1879; and Geol. Queensland, p. 151. 



** Report on Gympie Goldrield, l.s89; Aust. Assoc. Adv. Sc, i., p. 297, 1889; also Jack, 



Geol. Queensland, p. 77, 1892. 



tt Report JUning Department, Vict., 1888, p. 81. 



