﻿SUMMARY OF THE CONTENTS. 681 



The 5 forms marked * are only known from the younger 

 (upper) yoldia clay (see below). 



The species of molkisca of the yoldia clay are all of them 

 high arctic and nearly all known living in the Kara Sea. On 

 p. 33 are enumerated a number of foraminifera collected in the 

 yoldia clay near Moss; on p. 670 polystomella ardica, Park. & 

 Jones, a typical high arctic species, is added to this list. 



Pp. 55—73. The Depth of the Deposition of the Yoldia Clay. 



In this chapter is given an explicit inquiry into the impor- 

 tant question of- the depth of the deposition of the yoldia clay. 

 An attempt is made to prove that the typical and common 

 species of the yoldia clay live in abundance in the high arctic 

 seas only at depths from about 10 to 30 metres; a number of 

 high arctic species living at greater depths (as for instance 

 peden gronlandicus^ area glacialis, portlandia lenticula, sipho- 

 nodentalium vitreum, the deepwater species of margarita, hela, 

 etc.) have never been found in the typical older yoldia clay with 

 the great varieties of portlandia ardica, macoma calcaria, etc. 



As the yoldia clay on Jomfruland, at Nevlunghavn, Sande- 

 fjord, Tønsberg, Åsgårdsstrand, Horten, Moss, in Råde by the 

 Glommen, etc. occurs on the present shoreline (and only a few 

 metres above it) it is justifiable to conclude that at the time of 

 its deposition, the Kristiania region can only have been sub- 

 merged about 20—30 metres deeper than it is at present. 



Now the yoldia clay in all the occurrences enumerated also 

 continues below the surface of the sea, and fossil valves of 

 portlandia ardica are dredged up from the sea-bottom all 

 round the coast of Norway, from depths down to more than 70 

 fathoms. It is then without all doubt extremely probable, that 

 during the earher time of the deposition of the older yoldia clay, 

 that is, before the ra-time, the land, especially Southern Norway 

 and the Kristiania region, must have been uplifted higher above 

 the sea than it is at present. 



