GEOSCAN, résultats de la recherche


TitreThe reduced Lakes Erie and Ontario, a severe response to a past drier climate
AuteurLewis, M; Anderson, T W; Cameron, G; King, J W; Heil, C W, Jr.
SourceIAGLR2010, Great Lakes Conference, abstract book; 2010 p. 148-149
Séries alt.Secteur des sciences de la Terre, Contribution externe 20090410
Réunion53rd Annual IAGLR Conference on Great Lakes Research; Toronto, ON; CA; mai 17-21, 2010
Lat/Long OENS-84.0000 -76.0000 44.5000 41.0000
Sujetsprofondeurs des eaux lacustres; lacs; eaux lacustres; climat; effets climatiques; analyse environnementales; Holocène; Changement climatique; hydrogéologie; géologie de l'environnement; Cénozoïque
ProgrammeÉtudes paléo-environnementales sur les changements climatiques, Géosciences de changements climatiques
Résumé(disponible en anglais seulement)
Recent analysis of geological evidence of former water level indicators has revealed a long phase of closed basin conditions in the lower Great Lakes in which water levels were drawn down below their overflow outlets for longer than 5 millennia prior to 6000 years ago by evaporation in the drier-than-present early Holocene climate. Similar lowstands existed in the upper Great Lakes basins but for a shorter period of time (about 500 years) due to the prolonged inflow of glacial meltwater. This new understanding results from at least two new developments in Great Lakes geoscience: 1) removal of the distorting effects of differential glacial rebound so the original elevations of lake-level indicators and outlets could be compared, and 2) abandonment of a long-held paradigm that past lakes always overflowed their outlets. Reconstructions show that the lakes fell up to 17 m (Erie) and 30 to 40 m (Ontario) below their overflow sills. These severe lake responses to the drier early Holocene climate could serve as test beds for hydrological models, and as examples to enhance public understanding of the sensitivity of the lakes to climate change