K.— BOTANY. 205 



Prof. Schuchert, of Yale University^ — ' Review of the late Paleozoic Form- 

 ations and Faunas, with special reference to the Ice-Age of Middle 

 Permian time ' {Bull, Geol. Soc. America, Vol. 39, pp. 769-886, 1929). 

 Though this is hardly a suitable occasion for a full discussion of a con- 

 troversial subject, it is not inappropriate that I should ask my audience 

 to consider a few of the arguments advanced by the distinguished American 

 geologist, also certain pieces of evidence which seem to me worthy of 

 attention. Mr. Du Toit is more capable than I am of dealing with some 

 of the questions under dispute, and I hope that he also will reply to Prof. 

 Schuchert, who believes that both Mr. Du Toit and myself as well as 

 certain other authors hold heretical opinions. 



Prof. Schuchert concludes the summary of his views with these 

 words : ' It is therefore certain that the widely spread tillites (that is the 

 old boulder clays) are of Permian time and in all probability of late Middle 

 Permian age. In any event, not even those of Australia can be of Upper 

 Carboniferous time.' He bases this very definite pronouncement mainly 

 on the fossil animals obtained from marine strata associated with the 

 Palaeozoic boulder beds. After referring to views expressed by the late 

 Dr. Arber and by myself that ' the lowest beds containing remains of the 

 Glossopteris Flora are, in all probability, homotaxial with the Upper 

 Carboniferous rocks of the northern hemisphere,' he adds : ' They believe 

 that while the cosmopolitan Upper Carboniferous Flora was living in the 

 northern hemisphere, the Glossopteris one was in existence south of the 

 equator.' My view is that no Upper Carboniferous Flora was in the 

 strict sense cosmopolitan. Prof. Schuchert continues : ' This contem- 

 poraneity of the very different northern and southern floras can 



not be maintained when the floras are checked into the stratigraphical and 

 marine records. We will repeat,' he adds, ' that even though there are in 

 none of the continents of the southern hemisphere, other than the west 

 coast of South America, any known plant-bearing rocks of Upper Carboni- 

 ferous age, yet in this single occurrence there is at hand a small plant 

 assemblage of the cosmopolitan Upper Carboniferous Flora.' These South 

 American plants were assigned by Mr. Berry to an Upper Carboniferous 

 horizon, but both Dr. Gothan and myself believe them to indicate a 

 Lower Carboniferous age. The glacial deposits are stated by Prof. 

 Schuchert to be one of the finest means of making definite time correlations 

 from continent to continent, but in another place he admits that the 

 scattered tillites of Gondwanaland, though regarded as the products of 

 one glacial age, are not all exactly of the same age. It may well be, he 

 adds, ' that the basal moraines in South Eastern Australia are somewhat 

 older than those of other continents, as maintained by David and Siiss- 

 milch ; but by no possible chance can the Australian tillites be stretched 

 into the Upper Carboniferous, nor does it seem possible to place them even 

 below the Middle Permian.' Here we have an assertion which challenges 

 criticism. It has been said that ' a sweeping, unqualified assertion ends 

 all controversy, and sets opinion at rest ' ; but I am sure that Prof. 

 Schuchert will agree, that before accepting an assertion as final we should 

 satisfy ourselves that it rests on sound foundations. I am indebted to 

 my friend Sir Edgeworth David for information on the succession of 

 boulder beds and fossil-bearing strata displayed in a section in the Hunter 



