Open AccessSubglacial to proglacial sediment transition in a shallow ice‐contact lake
Author(s) -
II CHARLES W. ROVEY,
BORUCKI MARK K.
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.tb00631.x
Subject(s) - geology , drumlin , geomorphology , glacier , glacial period , moraine , ice stream , stratification (seeds) , facies , transition zone , paleontology , geochemistry , oceanography , sea ice , cryosphere , seed dormancy , germination , botany , structural basin , dormancy , biology
A complete subglacial to glacial‐lacustrine facies transition is described from a temporary exposure in the Lake Michigan bluffs of southeastern Wisconsin. This transition occurs where a Late Woodfordian terminal moraine intersects the bluff line and grades from basal meltout till to chaotic diamicton to rhythmites over an abrupt 90 m lateral distance. The boundary of the subglacial meltout deposits is marked by an abrupt increase in pebbles and cobbles, which cluster at specific horizons, producing an incipient stratification. Thereafter, the diamicton develops contorted flow structures with progressive segregation into coarse and fine‐grained fractions, ultimately into well‐stratified rhythmites.