lOO JOHAN KIÆR. M.-N. Kl. 



as we have seen the upper part of our Lower Cambrian. It is superim- 

 posed by the Middle Cambrian zone with Paradoxides Ølandicus, with an 

 apparently even transition both as regards fauna and sediment. Farther 

 south we see quite different conditions. As we have long known, all the 

 Lower Cambrian beds just considered are absent at this spot. Direct on 

 the Archaean rocks we meet coarse clastic sediments in somewhat varying 

 but generally small dimensions (from less than i m. to 12 m.). At some 

 places there are typical conglomerates, at others sandstone alternating with 

 sandy shales, or even somewhat fine sandy shales. This basal formation 

 is superimposed immediately by dark shales with beds and ellipsoids of 

 limestone, in which the Paradoxides Tessini fauna have been shown at 

 several places. The Paradoxides Ølandicus zone is quite lacking there. 



The explanation of these conditions was first given by W. C. Brøgger ^ 

 In the Lower Cambrian age the southern part of Norway formed a continent 

 the limitations of which we shall refer to later on. Subsequently there was 

 a transgression of the sea from the north towards the south, during which 

 the coarse clastic basal formations were deposited. It is, however, some- 

 what more difficult to determine the time of this transgression, and there- 

 by the age of the basal deposits. As they contain at several places the 

 small shells of Torellella laevigata Lnrs., that has been regarded as a typical 

 Lower Cambrian type fossil, these basal sediments have generally been 

 considered to be Lower Cambrian. 



A number of circumstances are in opposition to this view. In fact at 

 several spots the remains of a distinct Tessini fauna have been found 

 directly over the coarse clastic basal sediment containing Torellella laevigata. 



It was thus proved by O. Holtedahl- to be the case at Hennungbygden 

 between Hadeland and Toten, and farther to the N.-W. at Nordsinnen. 



Further, e. g. at Slemmestad (about 14 miles south of Christiania) it 

 can be shown that the upper boulders of the small conglomerate there, pass 

 into dark limestone with a large number of fossil remains, the latter belon- 

 ging to marked Tessini fauna. However, Torellella is not found there. 



If the conglomerate at these places were Lower Cambrian, the entire 

 Ølandicus zone could not have left the slightest traces there. It is concei- 

 vable. However another solution is far more likely, viz. that 

 the basal conglomerates with Torellella in reality are not Lower 

 Cambrian, but were deposited in the lower part of the Middle 



' "Norges Geologi" in "Norge i 19de Aarhundrede", 1905. 



2 Hennungbygdens alunskiferfelt. (Norsk Geolog. Tidsskrift Bd. II, No. 6, 1911). 



Iagttagelser over fjeldbj-gningen omkring Randsfjordens N.-ende (Norges Geol. Unders. 



Aarb. 1915I. 



