﻿692 SUMMARY OF THE CONTENTS. 



summits formed, „nunataks" ; at the time of the inner ra, the 

 ice-sheet must have heen so thin, that the glaciers in the peri- 

 pheric parts of South Norway only filled the valleys. At the 

 epiglaciai time the ice filling of the Mjøsen vailey probably reached 

 only up to about 400 m. above sea-level. 



The sinking of the land began at first in the peripheric 

 parts, and little by little extended also to the central parts. It 

 is probable that the velocity of sinking was greater during the 

 ra time and became slower by degrees during the time of the 

 retreat of the ice from the ra to the epiglaciai station, where 

 the sinking finally ceased, and after a protacted intermission 

 changed to uplift. 



As to the change of cliniate during the sinking, a thorough 

 study of the moUusc fauna of the clay beds compared with the 

 living mollusc-faunas allows of its being followed in relation to 

 the sinking and to the retreat of the ice border. Thus during 

 the ra-time the average temperature of the year in the Kri- 

 stiania region has probably not been higher than ^ 8*^ to -^ 9" C, 

 in the beginning of the ra-time probably still lower. During the 

 deposition of the younger yoldia clay and the older area clay, 

 the average temperature has probably risen to -i- 4° G. and to 

 -i- 3^ G. ; during the deposition of the middle area clay pro- 

 bably from -1-20 G. to about + V20 G.; and finally, during the 

 deposition of the youger and youngest area clay, the average 

 temperature at Kristiania has probably risen to about + 2*^ G., 

 during the close of the sinking, in epiglaciai time. 



For the whole period of sinking between the deposition of 

 the outer ra, and the epiglaciai moraines I propose the name: 

 ))the Kristiania period«. 



