1913] THE QUATERNARY SECTION OF FOSS 13 



of only one millimetre arranged in groups of a thickness of 6 

 to 10 millimetres or as a mean thickness 8 millimetres each of 

 the clay layers being separated by layers of fine sand of a 

 reddish-grey colour; this sand-layers are thin as paper, but every 

 eight of the layers is conspicuously more prominent than the 

 other ones. In the very uppermost part of the layer a single 

 small stone is rarely met vvith in the clay. This clay is fossil- 

 bearing, the following molluscan fossils having been met with : — 



Nucula tenuis Mont. 



Portlandia lenticula Moll., short and thick. 



Area glacialis Gray, forma typica. 



Axinus flexuosus Mont. 



Abra longicallis Sc. 



Abra nitida Mull. 



Siphonodentalium vitreum Sårs. 



XVIII. This deposit is a very interesting one and rather 

 complex. Several deposits of a similar kind in the valley of 

 Aker I have on former occasions regarded as contemporaneous 

 with the Aker stage of frontal moraines of oscillation. And, 

 I am tended to believe that the deposits here in question belongs 

 to the very same series. 



In ascending order this complex series may be divided into 

 the following separate layers as follows: — 



a. Sand, thickness 15 mm. 



b. Clay, thickness 8 mm. 



c. Sand, thickness 15 mm. 



d. Clay, thickness 27 cm. 



This lower part of the series consequently prove to be of a true 

 dichotome character. The two sand-layers, a and c, consist of 

 a well-assorted, fine sand of a reddish-grey colour; these sand- 

 layers further on prove to be laid up from thin-layers of a thick- 

 ness of only one millimetre each. Even the material of these 

 sand-layers gives a rather faint or slight reaction to HCI; in 

 some places, however, no such reaction is to be seen. The clay- 

 layers as well below the sand-layers as between them as also 



