Open AccessContemporary terminal‐moraine ridge formation at a temperate glacier: Styggedalsbreen, Jotunheimen, southern Norway
Author(s) -
MATTHEWS JOHN A.,
McCARROLL DANNY,
SHAKESBY RICHARD A.
Publication year - 1995
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/j.1502-3885.1995.tb00633.x
Subject(s) - geology , moraine , terminal moraine , ridge , glacier , temperate climate , tidewater glacier cycle , terminal (telecommunication) , physical geography , geomorphology , archaeology , paleontology , geography , pregnancy , telecommunications , botany , genetics , lactation , ice calving , computer science , biology
Terminal‐moraine ridges up to 6 m high have been forming at the snout of Styggedalsbreen for two decades. Based on intermittent observations during this period, combined with a detailed study of ridge morphology, sedimentary structures and composition during the 1993 field season, a model of terminal‐moraine formation that involves the interaction of glacial and glacio‐fluvial processes at a seasonally oscillating ice margin is presented. In winter, subglacial debris is frozen‐on to the glacier sole; in summer, ice‐marginal and supraglacial streams deposit sediments on the wasting ice tongue. The ice tongue overrides an embryonic moraine ridge during a late‐winter advance and a double layer of sediment (diamicton overlain by sorted sands and gravels) is added to the moraine ridge during the subsequent ablation season. Particular ridges grow incrementally over many years and exert positive feedback by enhancing snout up‐arching during the winter advance and constraining the course of summer meltwater streams close to the ice margin. The double‐layer annual‐meltout model is related to moraine formation by the stacking of subglacial frozen‐on sediment slabs (Krüger 1993). Moraine ridges of this type have a complex origin. are not push moraines, and may be characteristic of dynamic high‐latitude and high‐altitude temperate glaciers.