474 p. A. ØYEN [1914 



of radioaclive matter in its outer shell (L. c. pag. 204). Men 

 desuagtel uttaler Becker ganske liketil: In the present state 

 of knowledge, estimates of the age of minerals founded on ra- 

 dioactivitv can not command confidence« (Bull. Geol. Soc. Ame 

 rica, Vol.' 26, 1915, pag. 195). 



JoLY kom i »An estimate of the geological age of the earth« 

 til del resultat, at we think that it is at least justifiable to 

 claim that our present knowledge of solvent denudalion of the 

 earths surface points to a period of between eighty and ninety 

 millions of years having elapsed since water condensed upon 

 the earth, and rain and rivers and the actions continually pro 

 gressing in the soils began to supply the ocean with materials 

 dissolved from the rocks* (Smithsonian Report for 1899, pag. 

 287), men han regner da samtidig op ikke mindre end syv fak- 

 torer, der vil virke til at gjøre dette overslag til et minimum, og syv 

 andre faktorer, der vil virke i motsat retning, nemlig til at gjøre 

 det samme overslag til et maximum (L. c. pag. 288). Ved sedimen 

 tationen » the age is found to be 87 millions of years« (Joly: 

 The Birth-Time' of the World, 1915, pag. 12). Men vi kan her si 

 med P. Mc. ConxNell: »As the age of the earth does not parti 

 cularly concern the object of this book, we may leave il now 

 and let the scientists interested in the matter fight it out among 

 themselves* (The Elements of Agricultural Geology, London 1902, 

 pag. 13). Men det hai- dog sin betydning at erindre derom, før 

 vi gaar over til det emne, som her har en mere umiddelbar 

 interesse, nemlig de tidsforhold, der slaa r i forbindelse med den 

 kvartære lid og de forskjellige faser af denne. 



Førend vi gaar over hertil skal vi imidlertid erindre et ganske 

 almindeligt mathemalisk problem: »The criterion for the besl 

 value is by no means evident. Perhaps it will be generally con 

 sidered that the best value is the probable value, that is, the 

 value that is just as likely to be exceeded as not in the long 

 run, so that the probabilily that the observed value shall fall 

 shorl of the probable value is V'2 and the probabilily that the 

 observed value shall exceed the probable value is ^2. Certainly 

 the besl value cannot be defined as Ihe most probable value, 

 that is, the value whose probabilily is a maximum, because il 

 turns out Ihat the probabilily is sometimes a maximum for more 

 than one value; Ihe probabilily may eveji have equal maximum 

 for two or more values« (W. E. Story: A new general Theory 

 of Errors, 1904, pag. 169). 



Samtidig med at Hedleys skildring af The Paleogeographi 

 cal Relations of Anlarctica« opruUer for os el konkret forelig 

 gende billede, vil man i de i vedføiede slulningsord fra hans 

 interessante afhandling foruten et saadant ogsaa kunne se et 



