Den tillittførende formasjonsgruppe i Alta - en jevnføring med Øst-Finnmark og med indre Finnmark.

Abstract

The Bosskop quartzite, the tillite layer and the succeedingbeds in Alta wer mapped by the present author in 1962. The mapping wasdone on aerial photographs at about 1:20 000. Fig. 1 give the result ona reduced scale. In this paper the name Bossekop group is restrictedto the 100 to 150 m thick succession of quartzites and shales betweenthe (Precambrian) Raipas suite and the tillite. The tillite was foundto rest with a slight unconfomity on the Bossekop group. The nameBorras group is in this paper proposed for the following group offormations in the Alta district: 1) Tillite, with gradationaltransition to 2) light coloured sandstones with conglomerates andshales and 3) red and green shales and sandstones. The tillite is about10 m thick, the next formation 10 to 30 m, the red and green shale andsandstones up to the thrust plane mostly 20 to 30 meters. The Borrasgroup has, in the view of the present author, a striking resemblance tothe beds beginning with the upper tillite of eastern Finnmark (S. Føyn,1937, p.p. 86-87).