128 THE JOURNAL OF GEOLOGY. 



greater specific gravity in a great degree replaced the melting ice 

 margin, the consequence appears to have been that the land finally 

 lost in height perhaps as much as 200 to 400 meters. We shall find 

 analogous phenomena in other glaciated countries. 



The thickness of the inland ice in Norway at this time we are 

 able to estimate by the upper limit of foreign boulders and by 

 the lower limit of the rocks on mountain summits which were 

 not reached by the ice sheet. Where a great continuous scoring 

 ice sheet has worked we find in Norway, as in Greenland and 

 elsewhere, the smooth undulating surface lines with fresh rock 

 surfaces. Higher up, above the reach of ice, we find the minatak 

 formation with peaks and cirques (botner) and with highly 

 weathered rocks and mighty talus and other debris. By such 

 limits we can approximately determine that the maximum height 

 of the ice sheet in southern Norway was below 2000 meters, in 

 northern Norway about 1200 to 1500 meters, these being reckoned 

 from the present sea level. As the mean height of the Norwe- 

 gian highland may be estimated at 800 to lOCO meters, and 

 as only central Norway reaches more than 1200 meters, we 

 get an ice sheet which, near its axis, will measure only about 

 800 to 1000 meters. To this thickness of the ice the depres- 

 sion of the land answers very well according to O. Fisher's 

 theory. 



The first great Quaternary glaciation of Norway was followed 

 by other great climatic changes. To get a more handy term- 

 inology than the common periphrastic nomenclature, I have pro- 

 posed, for the most pronounced periods, the names proteroglacial 

 for the earlier great ice age as distinguished from the well-known 

 last great glaciation that followed — the detiteroglacial. I have 

 chosen and press for acceptance at the Congress terms implying 

 the first and the second of tzvo periods because these two glacia- 

 tions seem to be demonstrable for all glaciated countries. The 

 names cannot well be misunderstood, and if, perchance, as some 

 American and German geologists assume, a third separate glacia- 

 tion can be proved, it will be easy to give it a name apart. So 

 far we can only distinguish in Norway preglacial, proteroglacial, 



