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P. A. ØYEN
lands during the glacial period.»148 Davis uttaler ogsaa senere ganske
liketil, at «the observations and discussions that have led to a belief in
strong glacial erosion are to be found in many different essays. Some of
the earlier essays were based on almost intuitive insight; as when Ramsay
was led to advocate the glacial erosion of lake basins, Gastaldi to accept
the glacial erosion of cirques, and Helland to announce the glacial erosion
of fiords. Many of the later essays are more surely founded on compa*
rative studies, such as those on over*deepened valleys in the Cascade
mountains of Washington by Gannett and in the Alps by Penck; on the
fiords of Alaska by Gilbert and of New Zealand by Andrews; on the
cirques of the Sierra Nevada of California by Johnson, of the Carpathians
by de Martonne, and of the Big Horns by Matthes; and on the sharpe*
ned peaks of the Alps by Richter, and of Skye by Harker. There has
thus been a great growth in the number of facts to be explained and a
notable advance in the methods by which explanation is reached. It seems
no exaggeration to say, in view of all this progress, that the sculpture of
mountains by glaciers has been given that degree of extreme probability
which we may fairly call demonstration.»149 Ja han uttrykker det noget senere
endnu skarpere: «The sculpture of mountains by glaciers is indeed now
proved by so many facts, widely and yet systematically distributed, that
it savours of extreme conservatism any longer to deny the efficacy of
glacial erosion.» 150
Det er jo ogsaa ganske merkelig, at W. M. Davis i sin avhandling
til Stockholmkongressen i 1910 «American Studies on glacial Erosion»161
ikke finder anledning til at nævne hverken Ramsay eller Helland, men
alene anfører, at «the large majority of American geologists and physio*
graphers now accept — — — the theory of glacial erosion».152 Og naar
vi saa hører Davis uttale: «the cirques have frequently been so much en*
larged as almost to consume the preglacially rounded domes and spurs,
and sometimes even to transform them into sharpened peaks and serrated
ridges; while the long main troughs have been so maturely deepened as
to exhibit repeated instances of lateral hanging troughs where small branch
glaciers joined the trunk glacier» 15S, saa er jo ikke dette igrunden nogen
anden lære end den allerede i det foregaaende efter Helland fremstillede.
Det er derimot ikke vanskelig at forstaa, at Reusch saa ivrig søker
at overføre disse amerikanske betragtninger paa norsk jordbund, men der*
imot vanskeligere at forstaa ham, naar han uttaler: «when we possessed
only a knowledge of practically one ice*age, and found that in some
places the scouring had only slightly modified the pre*existing forms of
38
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