SECTIONAL TRANSACTIONS.— A. 321 



Unconformity. Manigotagan phase : Quartzite, con- 



Nemo System: Quartzite, grey- glomerate, greywacke, slate, 



wacke, arkosic conglomerate, iron _ . 



formation. Base not ex P 0Sed - 



Granite and granodiorite (pebbles 

 Base not exposed. in Manigotagan conglomerates). 



Granite Csource of Nemo arkose, etc.) . 



From these records it may be inferred (a) that the age of the earth is not 

 less than 1 ,900 to 2,000 million years, and (b) that the conditions of tempera- 

 ture and rainfall controlling the weathering responsible for the raw materials 

 of these oldest sediments probably fell within the range of present-day 

 climatic conditions. A further indication that there has been no secular 

 variation of climates during geological time is provided by the distribution 

 in time of former ice-ages : 



Million 

 Years. 



0-1 Pleistocene. 



200 Permo-Carboniferous. — South America ; South and Central 



Africa ; India ; Australia. 

 500 Eo-Cambrian. — Spitzbergen ; Greenland ; Scandinavia ; South 



Australia. (?) Yangtse, China. 

 600-700 Transvaal-Nama-Katanga. — S.W. Africa ; Angola ; Congo ; 

 Rhodesia ; Transvaal. (?) Simla, India. (?) Broken Hill, 

 N.S.W. 

 800-900 Huronian. — Cobalt, Ontario. (?) Wit water srand, Transvaal. 

 1000-1100 Bothnian. — Finland. 

 (?)>noo Damara. Chuos district, S.W. Africa. 

 (?) > 1650 (Unnamed). — Medicine Bow Mountains, Wyoming. 



The characteristics of the Pre-Cambrian varved clays so closely resemble 

 those of the Pleistocene as to leave no doubt that they were formed under 

 seasonal variations as marked as those of to-day. In the older examples, 

 as in other ancient sediments, iron is largely ferrous, indicating an atmos- 

 phere poor in, or free from, oxygen. 



Geological evidence indicates that for nearly 2,000 million years there 

 have been no astronomically significant changes in the thermal and dyna- 

 mical relations between the earth and the sun. There is a hint of large- 

 scale periodicity in the recurrence of terrestrial glaciation (though the data, 

 as yet, are far from complete), and this may point to a corresponding 

 periodicity in the fluctuations of solar radiation. 



Prof. E. A. Milne, F.R.S. — The evolution of the Solar System : 

 dynamical aspects. 



In recent papers the author has derived the forms of the laws of dynamics 

 and of gravitation from purely kinematic considerations based on the 

 analysis of the description of motion in terms of the individual observer's 

 awareness of a temporal experience. The laws thus derived differ in a 

 significant way from the usual empirical formulations of these laws, more 

 especially in the occurrence in them of the kinematic time-variable t. It 

 is now possible to show that these rationally derived laws pass over into 

 the exact form of the local empirical Newtonian formulations on transform- 

 ing from kinematic time t to dynamical time t, where t= t log (t/t ) + t , 

 where t is the present value of t obtained from the expansion of the universe. 



M 2 



