^0 Tromso Muséums Auraliefter 29 — 1" 



the retreating iee front. Their mutual age is more difficult to 

 ascertain, but both the fossils and the f ossiferous beds them- 

 selves give an answer to not a few important questions. 



The occurrence of shells in the bluff at Ruffen proves 

 that the land has been sinking during the building of the 

 sand terrace here for the deepest strata contain a shallow wa- 

 ter fauna only comprising arctic and boreal species as Ma- 

 coma calcaria and Mytiltis edulis, while the upper fossiliferous 

 strata contain Abra prismatica, young ones of Mya intncata 

 etc., all of which in recent time live at a depth of about 20 m. 

 The shell-bearing deposits in the river bed at Øverbækli 

 show the same sinking of the land for the fossils are found 

 in sand and gravel, deposited at the bottom of a channel 

 previously dug out in older sediments by running water. 



The fauna in the bluff above Stenbækhaug is older than 

 that in the upper strata at Ruffen for here are only arctic 

 and boreal forms but in the latter place are some lusitanic 

 species too. Besides the matter of that terrace shows that 

 previous to the terrace building the older sediments had been 

 fully washed out of the narrow channel between Jamtli and 

 Stenbækhaug for the terrace consists only of sand and gravel 

 from top to bottom. The shore-line lay at that time hardly 

 more than 20 m. higher than now. The boreal-lucitanic fauna 

 at Ruffen lived at a depth of 20 m. and the shore-line of that 

 time must therefore have been situated at least 65 — 70 m. above 

 the present sea level. Littoral beds too on the said level above 

 the sea indicate this situation of the shore-line during the maxi- 

 mum of this last submergence, which consequently amounts 

 to at least 45—50 m. 



The fossils in the upper shell-bearing strata in the bluff 

 at Ruffen probably belong to a Tapes-îâuna, for lusitanic forms 

 as Cultellus pe Unci dus and Abra prisma tica are not found 

 in older deposits elsewhere in our country, according to Brøg- 

 ger, Oi en and others (Brøgger: Om de senglaciale og post- 





