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TitleA younger glacial Lake Iroquois in the Lake Ontario basin, Ontario and New York: re-examination of pollen stratigraphy and radiocarbon dating
AuthorLewis, C F MORCID logo; Anderson, T W
SourceCanadian Journal of Earth Sciences vol. 57, no. 4, 2019 p. 453-463, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190011
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf; html
NTS30M; 30N; 31B; 31C; 31D; 31E/01; 31E/02; 31E/03; 31E/04; 31E/05; 31E/06; 31E/07; 31E/08; 31F/01; 31F/02; 31F/03; 31F/04; 31F/05; 31F/06; 31F/07; 31F/08; 31G/01; 31G/02; 31G/03; 31G/04; 31G/05; 31G/06; 31G/07; 31G/08
AreaLake Ontario; New York State; Canada; United States of America
Lat/Long WENS -78.0000 -73.5000 45.5000 43.0000
Subjectssurficial geology/geomorphology; stratigraphy; paleontology; geochronology; Nature and Environment; Science and Technology; palynology; pollen stratigraphy; vegetation; fossils; radiometric dating; radiocarbon dating; glacial history; glaciation; ice margins; deglaciation; glacial lakes; Wisconsinian glacial stage; emergence; shoreline changes; depositional history; varves; marls; gyttja; clays; silts; sands; detritus; gravels; glacial deposits; tills; surface waters; lakes; grain size distribution; Lake Ontario Basin; Glacial Lake Iroquois; Picea sp.; Pinus sp.; Quercus sp.; Champlain Sea; glaciolacustrine sediments; Trees; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; profiles; tables; lithologic sections; time series
ProgramClimate Change Geoscience Coastal Infrastructure
Released2019 07 24
AbstractRevision of palynochronologic and radiocarbon age estimates for the termination of glacial Lake Iroquois, mainly based on a currently accepted younger determination of the key Picea-Pinus pollen transition, shows agreement with recently established constraints for this late glacial event in the Lake Ontario basin at 13 000 cal years BP. The date of emergence or isolation of small lake basins reflects the termination of inundation by glacial lake waters. The increasing upward presence of plant detritus and the onset of organic sedimentation marks the isolation level in the sediments of a small lake basin. The upward relative decline and cessation of pollen from trees such as Pinus, Quercus, and other thermophilous hardwoods that were wind transported long distances from southern areas also mark the isolation of inundated small lake basins by the declining water level of Lake Iroquois as local vegetation grew and local pollen overwhelmed long-distance-transported pollen. Reexamination of data in small lake basins north of Lake Ontario using the above criteria shows that the age range for the termination of Lake Iroquois derived from these data overlaps other age constraints. These constraints are based on a varveestimated duration of post-Iroquois phases before incursion of the Champlain Sea, a newly discovered late ice advance into northern New York State, and the age of a mastodon at Cohoes, New York. The new age (13 000 cal years BP) for Lake Iroquois termination is significantly younger than the previous estimate of 11 800 14C (13 600 cal) years BP.
Summary(Plain Language Summary, not published)
Glacial Lake Iroquois filled the Lake Ontario basin between Ontario and New York State to more than 36 m above the present lake level. The age of Lake Iroquois was estimated from analyses of sediment cores from small lake basins that had been submerged by the former glacial lake. A new more reliable radiocarbon age for a key tree pollen horizon was used to constrain the ages when the small lake basins were probably isolated as the large Lake Iroquois drained. The age range agreed with other age indicators showing that Lake Iroquois ended about 13 000 years ago.

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