Nr. 6] KVARTÆR-STUDIER I TRONDHJEMSFELTET 131 



being cold eiiough in winter to kill off all but the hardiest trees 

 and shrubs but not sufficently cold to reduce the whole vegetation 

 to the few perennial herbs and stunted shrubs which are charac- 

 teristic of arctic regions today. Of course this evidence is of value 

 onlj^ as indicating the climate during the coldest period of the 

 ice invasion, just as the percentage of herbs in a flora is indi- 

 cative of the minimum winter tempera ture of the region. As lo 

 the climate of the presumabh^ warmer interglacial periods it tells 

 us nothing«. (The Journal of Geologv, Chicago, June 1915, Vol. 

 23, pag. 299). 



For at imidlertid disse vigtige, væsentlige og interessante for- 

 hold skal kunne ha nogen indflydelse paa vor opfatning af enkelt- 

 fænomenernes sammenhæng, er vi nødt til at betrakte dem som 

 lovmæssig sammenbundne, thi ellers vil de let komme til at 

 opløse sig for vor erkj endelse i like saa mange enkelte kjends- 

 gjerninger, der meget snart vil bli saa mange, at vi ikke længer 

 er istand til at sammenknytte dem eller forbinde dem til noget 

 helt. Selv den biologiske verden, med de mange saa fint i hin- 

 anden flettede love og former af forskjelligt slags, vil styrte sam- 

 men i en kaotisk blanding, uforenelig med dens egentlige væsen. 



I et foredrag om » Istiden og de britiske øers nuværende flora« 

 som Clement Reid holdt ved British Association's møte i Ports- 

 mouth 1911, uttalte han imidlertid: »Aartuseners tilfældige til- 

 førsel av frø forklarer de nuværende eiendommeligheter i den 

 geografiske utbredelse bedre end alle forandringer av hav, land 

 eller klima« (Naturen 1912, pag. 87). I denne uttalelse maatte 

 vi fra et kvartærgeologisk synspunkt nødvendigvis se en dyp 

 skepticismes frø, hvis ikke den samme, erfarne forsker nogle aar 

 i forveien hadde ganske liketil fortalt os: »We have no indication 

 in our Tertiary or later deposits of a number of alternating Glacial 

 and Interglacial Epochs, such as are required on the theory of 

 Croll adopted by Professor James Geikie. On the other hand, the 

 evidence is perfectly clear that this country saw two cold Epochs, 

 and certain indications make one suspect that there may have 

 been a third, less rigorous« (The Origin of the British Flora, 

 1899, pag. 44). Og den samme forsker fortæller os, at » Britain, 

 within the lifetime of existing species, has been subjected to 

 many fluctuations of climate, which have left their mark on the 

 flora» (L. c. pag. 8). 



SiNNOTT og Bailey kom til det resultat, at »at least half of 

 the pre-Glacial vegetation of the north temperate zone seems to 

 have been composed of woody plants, indicating the occurrence 

 of a rather mild winter. The advent of the Glacial period resul- 

 ted in very great extermination of the flora, but herbs suffered 

 much less than did woody plants. In America the vegetation 



