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and may by these means get some idea as to the length of the first great ice age. The farther we go from our own time the more wholly conjectural will our numbers become, of course. But as other more reliable measures as yet are wanting, I shall venture a first approximation, calculating the time in which the enormous proteroglacial marginal glaciers eroded our fjords, as five to ten times the epiglacial time in which our great epiglacial lakes were scooped out—the higher estimate in this case being somewhat more probable. This would perhaps make 100,000 to 150,000 years for the whole proteroglacial period, i.e., about five times the duration of the deuteroglacial time—a relation which, as far as I see, is in very good accordance with the general quantitative difference between the effects of the first and second great glaciations. This will give for the whole Quaternary-post-tertiary time about 140,000-200,000 years.

I see very well how precarious such computations may seem, especially as I here cannot give the detailed calculations—but I do not think it possible that any of these have given numbers five times too great or small. Under these circumstances they must be taken for a very good geological approximation. By getting parallel estimates from other glaciated countries, it will appear, I think, that we will have, on wholly geological ground, more positive and reliable data for the Quaternary chronology, than those derived from astronomical speculations.

I add for greater ease in comparison my reading of the Quaternary history of Norway in a tabular form.