Post-Tertiary or Qualernary 



68 p. A. øYEX [1914 



forhold tillater det. Men et ganske fremtrædende moment i et 

 saadant system blir dog, at det ved sin logiske lovmæssighet 

 aapner plads for nye, lilflytende kjendsgjerninger, ja tildels endog 

 anviser tomrum til utfyldning ved resultaterne af nye under- 

 søkeiser. Det vil saaledes være kun tilsyneladende, at et saa- 

 dant system tildels vil faa nogen lighet med Mc Gee's »Scheme 

 of a classification«. Vanskeligheten ved at bringe alle de mang- 

 foldige, enkeltstaaende kjendsgjerninger i kvartærgeologien ind 

 under en enhet er meget stor, derfor ogsaa den fremlrædende 

 vaklen, som man ofte møler. 



Den bekjendte engelske geolog. Sir Archib.\ld Geikie, gir 

 følgende oversigt: 



Pleistocene, Post-Pliocene, Diluvial 



or Glacial 



Recent, AUuvial, Human or Pre- 



hisloric. 



Men han tilføier: »Ihese subdivisions, however, are confes- 

 sedly very artificial, and it is often exceedingly difficult to draw 

 any line between them. The names assigned to Ihem also are 

 not free from objeclion (Text-Book of Geology, Vol. II (1903), 

 pag. 1300). Og videre tilføier han: It is hardly possible to arrange 

 the Post-Tertiary accumulations in a strict chronological order, 

 because we have no means of deciding, in many cases, their 

 relative antiquity, seeing thai as a rule they occur in scattered 

 areas, and not clearly superposed on each other. The order in 

 which they are classilied has often been determined by the- 

 oretical considerations, which are always subject to revision« 

 (L. c. pag. 1301). Denne betraklningsmaate har dog ikke hindret 

 ham i for Norges vedkommende at opta Brøggers inddeling af 

 den kvartære lagrække (L. c. pag. 1302, 1314, 1333). 



Hvad imidlertid direktøren for de Forenede Staters geologiske 

 undersøkelse ullaler i sin « Report 1892 — 93«, turde finde en 

 videre anvendelse og passe paa forholdene ogsaa inden andre 

 omraader: The pleistocene deposits are classed firsl by agency 

 and then by place wilh respect to the provinces inlo which they 

 fall and incidenlally they are grouped by time as representing 

 the direct and indirect producls of the different ice invasions. 

 B}' means of this classihcalion a large number of distinclions 

 have been made among the Pleistocene deposits, including, it 

 is believed, all that are required for the induslrial uses of the 

 countr}'. Moreover the researches have yielded a rude but useful 

 chronology of Ihe Pleistocene period in which the successive 

 episodes are clearly distinguished, and this is regarded as an 

 important contribution to the science of geology« (XIV Ann. Rep. 

 U. S. Geol. Surv. 1892—93, pari I, pag. 122). 



