Organic Remains in Finnish Subglacial Sediments

• Published in: Quaternary Research
• Main Authors: Punkari, Mikko, Forsström, Lars
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1995
• Subjects: Fennoscandia; Ice Sheet; Tundra
• Online Access: http://dx.doi.org/10.1006/qres.1995.1047; http://api.elsevier.com/content/article/PII:S0033589485710472?httpAccept=text/xml; http://api.elsevier.com/content/article/PII:S0033589485710472?httpAccept=text/plain; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S003358940003845X

Abstract Many sites in Fennoscandia contain pre-Late Weichselian beds of organic matter, located mostly in the flanks of eskers. It is a matter of debate whether these fragmentary beds were deposited in situ , or whether they were deposited elsewhere and then picked up and moved by glacial ice. The till-mantled esker of Harrinkangas includes a shallow depression filled with sand and silt containing, for example, several tightly packed laminar sheets of brown moss ( Bryales ) remains. It is argued that these thin peat sheets were transported at the base of the ice sheet, or englacially, and were deposited together with the silt and sand on the side of a subglacial meltwater tunnel. Subglacial meltout till subsequently covered the flanks of the esker near the receding ice margin. Information about the depositional and climatic environments was obtained from biostratigraphic analysis of the organic matter. Pollen spectra for the peat represent an open birch forest close to the tundra zone. A thin diamicton beneath the peat contains charred pine wood, recording the former presence of pine forests in western Finland. The unhumified, extremely well-preserved peat evidently originated during the final phase of an ice-free period, most probably the end of the Eemian Interglaciation. It was redeposited in the esker by the last ice sheet. Reconstructions of the Pleistocene chronology and stratigraphy of central Fennoscandia that rely on such redeposited organic matter should be viewed with caution.