THEORIES OF ATMOSPHERIC VARIATION. 



By David Traill, M.A., M.B., Ch.M., B.Sc. 



(Abstract.) 



The author refers to the views enunciated by him at 

 Beaufort West on the 13th June. 19 10. and in his previously 

 pubhshed paper* subsequent to which he had found similar 

 theories put forward by Prof. Arrhenius. The idea that there 

 had been successive waves of plant and animal life on the 

 earth, due to corresponding waves in the proportions of carbon 

 dioxide and oxygen in the air, he considers to be untenable. He 

 criticises adversely Sir E. Ray Lankester's statement that, in the 

 absence of green plants, animals would eat one another, use 

 up the oxygen of the atmosphere, and be suffocated for lack of 

 that gas. He holds that all the carbon in animal bodies, if the 

 latter formed a closely compacted layer round the earth, six 

 feet in height, would be insufficient to use up the ])resent atmos- 

 pheric oxygen : there would, the author considers, still remain 

 about 2,000 parts of oxygen and 4 parts of carbon dioxide 

 in everv to.goo parts of air. The output of carbon dioxide, he 

 states, is limited by the quantity of carbon available, and there 

 is not at present enough unoxidised carbon on the earth's sur- 

 face to increase the amount of carbon dioxide in the atmos- 

 phere from four to five parts per 10,000. 



TRANSACTIONS OF SOCIETIES. 



Geological Sociktv of South Africa. — Monday, April 15th: Mr. H. S. 

 Harger, President, in the chair. — " Note on an interesting dyke intrusion 

 in the Upper Waterherg System :'" Dr P. A. Warner. The dyke referred 

 to is exposed in some excavations on the farm Buffelspriiit, north-west of 

 Warmbaths, the country rock being massive Waterberg sandstone. Accord- 

 ing to its mineralogical composition the rock is a camptonite, but on the 

 basis of its chemical constitution it may be grouped with the monchiquites. 

 Such dykes are invariably associated with the elasolite syenites and allied 

 plutonic rocks, but in the area where this dyke occurs no el?eolite syenite 

 is known to exist. This led the author to remark on the relative ages of 

 the plutonic members of the Bushveld Complex, and he concluded that 

 'there was no justification for assigning a post-Waterberg age to all 

 occurrences of eljeolite syenite in the Bushveld Complex. — " The Nama 

 System in the Cape Province :" Dr A. W. Rogers. The author showed 

 that the three series of rocks known as the Nieuwerust, Mahnesbury and 

 Ibiquas beds are parts of one great group, which is the same as that 

 known as the Nama System in German South-West Africa. 

 The true sequence of the three series is that given above, the Nieuwerust 

 beds being the oldest. The great gneiss and granite area, which extends 

 north from the Moed Verloren Hills to beyond the Orange River, include 

 acid intrusive rocks of two different dates, the earlier of pre-Nama age, 

 and the latter po.** r.Ialmesbury, and probably post-Ibiquas. 



* Report S. A. Ass. for Adv. of Science ; Cape Town, 1910, pp. 290-305. 



