346 SECTIONAL TRANSACTIONS.— C. 



3. Prof. Sir T. W. Edgeworth David, K.B.E., F.R.S.— TAe Determina- 



tion of the Age of the so called Permo-carboniferous Tillites of 

 Australia. 



Recent research in Australia, notably by C. A. Siissmilch, has shown that the oldest 

 and chief horizon of the so-called Permo-carboniferous glacial deposits of Australia 

 is associated, in N.S. Wales, with a fossil flora of Culm type, dominated by Ehacopteris, 

 Cardiopteris and Archmocalamites. Observations last year by Dr. A. L. du Toit, in 

 South America, prove that Cardiopteris is there associated intimately with the main 

 glacial horizon at the base of what is thereby shown to be an Upper Carboniferous 

 series. In India the Lower Productus Limestones, marking the base of the Permian 

 System, are considered to be stratigraphicaUy above the maruie beds with Eurydesma 

 cordatum, which immediately overlie and are partly interstratified with the Talchir 

 boulder beds. 



In South Africa the Dwj'ka Tillites pass westwards, to the south of Windhoek, 

 under the Eurydesma globosiim beds, and eastwards are followed by the Dwyka Shales, 

 which contain Crustacea of Upper Carboniferous affinities, the flora also indicating a 

 similar age. The present researches of H. D. Thomas of Cambridge on the so-called 

 Gastrioceras jacksoni, from the Irwin River coalfield of Western Australia, show 

 that that cephalopod, so abundant above the main glacial horizon there — the ' Lyons 

 Conglomerate ' — belongs probably to about the middle of Upper Carboniferous time. 



Thus, so far, throughout the Southern hemisphere evidence points to the chief 

 glaciation in late Palseozoic time having taken place not in Permian but in Upper 

 Carboniferous time. It is possible that evidences in New South Wales of a smaller 

 and later glaciation should be referred to very late Carboniferous or Early Permian 

 time. 



4. Prof. B. S. Moore. — The Keweenawan Series at the Eastern End of 



Lake Superior. 



The Keweenawan system, at the eastern end of Lake Superior, consists of three 

 series. The lower one is entirely igneous, the middle one igneous and sedimentary in 

 origin, and the upper one sedimentary. The genesis of these series is closely related 

 to the early history of the Lake Superior basin, which has been in existence since 

 Pre-Cambrian time. The development of dikes in this region, during the Lower 

 Keweenawan epoch, is believed to be the most remarkable ever discovered in the 

 Canadian ' shield.' The Middle Keweenawan is a series of interbedded lavas and 

 conglomerates, exceeding 16,000 feet in thickness, and the conglomerates contain 

 boulders of granite up to 4 feet in diameter. These have suggested a glacial origin to 

 most of the geologists who have seen them, but in the opinion of the author they are 

 not glacial. 



A study of this section has shown that the quartz-diabase and olivine-diabas© 

 dikes, 80 common in the Pre-Cambrian areas of Northern Ontario, probably belong 

 to the Lower Keweenawan and Middle Keweenawan respectively. 



The great epochs of igneous activity appear to have been one expression of the 

 disturbances accompanying the deepening of the Lake Superior basin.* 



5. Dr. R. T. GuNTHER. — (1) Notes on Exhibits of Blood Stains on 



Kimmeridgian Vertebra and of Jaw of Ursus Anglicus found in 

 Magdalen College. (2) The Oldest Stratigraphical Collection in the 

 World — the Collection of John Poynter, c. 1720. 



Afternoon. 

 Excursion to Hanborough, StonesfieM, &c. 



Friday, August 6. 



6. Discussion on Problems of the Thames Gravels. Opened by Mr. S. 



Hazzledine Warren and Dr. K. S. Sandford. 



* Published by permission of the Ontario Department of Mines. 



