AGE OF HUMAN RACE RICHARZ 455 



the publication citeil above * De Geer had calcuhited 12.000 years, 

 based on studies in Ka<;unda Lake; these studies were rcj^arded as 

 preliminary only; the hi^dier fi<;ure is based on more exact work of a 

 later date.)" 



De (Jeer's method was readily accepted and approved on the part 

 of geoloi^ists, even when he first reported it to an inteniational au- 

 dience and showed characteristic varved clays in Sweden to the mem- 

 bers of the Cieoh)<;ic Con<ji:ress. Since then this ajjproN ul lias become 

 universal anioni^st <?eolo<;ists and prehistorians. On the occasion of 

 the Twelfth International Geolo<]:ic Con«j:ress at Toronto in 1913, the 

 Canadian authority on jzlacial ^eolo«ry, A. P. Coleman, said: ''Prob- 

 ably the most accurate chronolofjy is that worked out skillfully and 

 patiently by Baron de Geer and his assistants."" The French pale- 

 ontologist Boule calls De Geer's method " la plus ingenieuse et la plus 

 suffisante." ^ Prof. James W. Goldthwait, of Dartmouth College, 

 writes in his introduction to Antevs's publication reporting on the 

 application of Do Geer's method to America: "An investigation so 

 precise in method and execution and so suggestive will give fresh 

 impulse to our studies of Pleistocene glaciation." * Robert W. Sayles, 

 geologist of the Harvard University Museum, after a careful exami- 

 nation of all the factors which might influence the deposition of the 

 clays in question, reaches the conclusion : " I feel convinced that the 

 seasonal theory is in a very strong position and that the danger of 

 its being abandoned is very slight." ° The late Prof. Eduard 

 Briickner, of Vienna University, one of the leading authorities on 

 the glacial geology of the Alps, accepts unreservedly De Geer's 

 method.*" 



Indeed, all modern geologists take it for granted that the chro- 

 nology based on clay varves is reliable. There exists no serious 

 adverse criticism of the method. Absolute chronologies based on 

 clay deposits were regarded with skepticism and mistrust, as long 

 as the thickness of the deposits was taken as the measure of time. 

 Climatic conditions are so variable and their influence on the amount 

 of clay carried along by rivers is so unaccountable that they can 

 never aflford precise measurement. This disturbing factor does not 

 enter into the new method. Variations in temperature and precipi- 

 tation certainly influence the thickness of the clay layers, but these 



*Cf. note 1. 



■R. Lid^D, Om isaTsmaitningen ocb den postglaclala landbSJningen i Ingermanland, 

 Geol. Foien. Forhandl.. Stockholm, 1911. vol. 33, pp. 271-2S0 ; G. de Geer. On the solar 

 curve, as datlnj? the Ice Ago. the New York Moraine iind NiaKara Falls through the 

 Swedish time scale, Geograflska annaler, 1926. vol. 8, pp. 274-284. 



•Congr^s g6oI. intern. XII., Compte remlu, Toronto, 1913, p. 435. 



^Marcelin Boule, Les hommes fossiles, Paris, 1921, p. 60. 



•Ernst Antevs. The reccsHlon of the last ice sheet in New England, Amer. Geogr. Soc„ 

 Research series no. 11, New York, 1921, p. IX. 



•Museum of Comp. Zoology, Memoirs, Carabrldge, Mnss., 1910, vol. 47, p. 61. 



:• Zeltschrlft fur Gletscljerkunde. 1921, Ud- XU. p. 5.'., 



