The Eocambrian series of the Tana district, Northern Norway

The main features of the geology of Finnmark have been elucidated by O. Holtedahl ( 19 18). His excursions in Finnmark during the Summers of 1914- 1917, he states, have mainly had the character of a general survey, with the exce ption of the map sheet Alta in West Finnmark, and in parts the map sheet Nesseby on the Varangerfjord, which districts have been more thoroughly investigated. In his paper of 1918 Holtedahl assumes that the "Sandstone divisions of Finnmark" are younger than Cambrian, mostly because the Porsanger sandstone south of the Porsangerfjord Iies apparently conformably above the Lower Cambrian Hyolithus zone. Meanwhile, on his studies of the sparagmite of central Southern Norway, he became aware of great similarities between the "Sparagmite division" and the "Sandstone divisions of Finnmark". In 1929, he aga in travels through Finnmark (Holtedahl, 1931 ), and, as he finds that the Porsanger sandstone is separated from the H yolithus zone by thrust plane, he states that most probably the Finnmark sandstone and the Sparagmite division are synchronous deposits, i. e. of EoCambrian age. In his paper of 1931, Holtedahl points out that a more detailed examination of the geological conditions in the environments of the upper part of the Tanafjord would largely contribute to a correct statement of the age, and to the knowledge of the glacial conglomerates of Finnmark. I was entrusted with this commission as in 1933 he organized geological research in Finnmark; I am giving herein the results of my work there during the Summers of 1933 and 1934. The financial support for the field investigations was granted by the Nansen Fond and Statens Forsknings Fond. The bulk of the work has been concentrated on the stratigraphical development, horizontally as well as vertically. Special study has been devoted to the tillites and their relation to the adjacent parts of the sequence. The study of the variations horizontally has in vol ved investigations over a rather extensive area; I therefore had to abandon many detail investigations which would have been desirable. As the greater part of the area was desolate territory, I have only in a few cases had the op portunity of visiting the localities more than once. The tectonics have only been studied in connection with the stratigraphy, and phenomena which are of little or no importance to the knowledge of the rocks or to the mapping, have had to be omitted. As to literature published earlier than 1918 on the rock formations of Fin nmark, I would refer to Holtedahl's paper of 1918. Later publications have been given by H. Reusch (1923), Th. Vogt (1929), O. Holtedahl (1931), H. Rosendahl (1931).