Glacial Chronology of Western Troms, North Norway

Abstract
An analysis of the glacial features on the narrow submarine continental shelf in Troms suggests that the Würm ice sheet covered the shelf. Large submarine end-moraine ridges on the outer part of the shelf represent the Egga substages that probably correspond to most of the classical Würm. Relatively large end and lateral moraines near the mouths of many fiords represent the Skarpnes substage, which is probably Oldest Dryas in age. The Tromsö-Lyngen moraines that lie 8–10 km inside the Skarpnes moraines are the most dominant end and lateral moraines in Troms. Emerged sandur deltas of the same age grade into the Main shore lines that also must be of Tromsö-Lyngen age. An arctic marine shell fauna characterized by the mollusk Portlandia arctica is common in the corresponding marine clays. A total of 13 radiocarbon dates have been made on shells from marine deposits corresponding to the Tromsö-Lyngen moraines. The dates are about 10,000 to 12,000 years B.P. Two bogs on top of the oldest Tromsö-Lyngen deposits were dated at 10,720 ± 240 and 11,680 ± 170 years B.P. The radiocarbon dates and the stratigraphy of the moraines suggest a division of the Tromsö-Lyngen substage into two glacial phases with an intervening phase of less glacial activity. The two glacial phases most likely represent Older Dryas and Younger Dryas periods. Small end moraines of the Stordal substage that usually lie at the heads of the fiords are probably of Pre-Boreal age. Recent moraines were found close to the existing glaciers.