E. D. Oldham — On Homotaxis and Contemporaneity. 295 



regarded them as of Carboniferous age. or, at the latest, representing 

 the interval between the Palaeozoic and Mesozoic eras of Europe, 

 while the latter, judging only from the plant remains found with 

 the coal, declared it to be of Mesozoic and even of Jurassic age. 



As regards the palseonto logical relations of these beds to each 

 other, and to the plant-bearing series of South Africa, the subject has 

 been so thoroughly treated by Dr. Blanford in his address that it 

 will be needless for me to enter into a repetition of the subject. I 

 may, however, remark that both in India and South Africa there is 

 a series of sedimentary formations which, if identity of fossils were 

 proof of contemporaneity, would have to be regarded as of contem- 

 porary and even coeval origin, and in both cases there are at the 

 lower limit of the series beds whose structure proves that they must 

 have been deposited through the agency of floating-ice. In Australia 

 there are some beds (the Bacchus Marsh beds of Victoria) which 

 similarly show that there must have been ice floating in large 

 masses on the sea beneath which they were deposited : these beds have 

 yielded a limited flora composed of three species of Oangamopteris, 

 of which one is identical with and the other two closely allied to 

 Talchir species. 



Thus we see that in India, in South Africa, and in Australia 

 there are beds whose nature indicates the existence of ice floating at 

 or near the sea-level, in latitudes which it does not now reach, and 

 that, as judged by the fossil plants contained in them and in the asso- 

 ciated beds, they must be regarded as homotaxial. The conclusion 

 is well-nigh irresistible that they all belong to a single Glacial epoch, 

 and are consequently strictly contemporaneous in origin. 



So far, I do not think any one will object to my conclusions ; they 

 have been foreshadowed by Mr. H. F. Blanford, 1 and as far as India 

 and Australia are concerned by Dr. Feistmantel, 2 who is by no means 

 disposed to underestimate the value of palseobotanical evidence, even 

 where opposed to every other consideration ; and so far I have been 

 able to accept and summarize Mr. Blanford's address. But in extend- 

 ing the same line of reasoning, and in trying to determine even 

 approximately the true date of this Glacial period, I shall have 

 to enter on more disputable ground, and to refer to information 

 acquired since Dr. Blanford's address was delivered. 



The first point to notice is that the Bacchus Marsh beds of 

 Victoria are not the only instance of Glacial boulder-beds occurring 

 in Australia ; for in New South Wales traces of Glacial action are 

 abundant in the marine beds below the Coal-measures. I am not 

 aware of any published record of this fact previous to my own notice 

 of the fact 3 ; but, as long ago as 1861, the lithological resemblance, 

 as seen in a collection of specimens from New South Wales, between 

 the marine beds of the Wollongong district and the boulder-beds of 



1 Quart. Journ. Geol. Soc. Lond. vol. xxxi. p. 519. 



2 Proc. Geol. Surv. Ind. 



3 Proc. Geol. Surv. India, vol. xix. p. 43 (1886). The substance of this paper 

 and of another in the Journ. As. Soc. Peng, for 1S84, is incorporated in the present 

 essay. 



