Jotnian Series

(from Old Norse jötunn, “giant”), a series of cross-bedded sandstones and quartzites with sills of diabases in Sweden and Finland. The series was differentiated by the Finnish geologist J.J. Sederholm in 1893. According to radiometric data (potassium-argon dating of bulk samples of the diabases), it corresponds to the lower and middle Riphean. In the USSR the Salmi series on the northeast shore of Lake Ladoga may be assigned to the Jotnian series.