The Early Lake Ontario barrier beach: evidence for sea level about 12.8–12.5 cal. ka BP beneath western Lake Ontario in eastern North America

Abstract

An overstepped, concave‐eastward, barrier beach beneath Holocene mud in western Lake Ontario has been delineated by acoustic and seismic reflection profiles and piston cores, and related to Early Lake Ontario (ELO). The average ELO barrier depth below present mean lake level is 77.4 to 80.6 m, or about −6 to −2.8 m above present sea level. Trend surface analysis of Champlain Sea (Atlantic Ocean) marine limits defined the contemporaneous marine water surface, and projections of this surface pass ~25 m above the outlet sill of the Lake Ontario basin and extend to the ELO palaeo‐barrier, a unique sand and gravel deposit beneath western Lake Ontario. ELO was connected to the Champlain Sea above the isostatically rising outlet sill for up to three centuries after about 12.8 cal. ka BP, while the glacio‐isostatically depressed St. Lawrence River Valley was inundated by the Atlantic Ocean. During the period of this connection, ELO level was confluent with slowly rising sea level, and the lake constructed a transgressive beach deposit with washover surfaces. ELO remained fresh due to a high flux of meltwater inflow. The marine water level connection stabilized water level in ELO relative to its shore and facilitated shore erosion, sediment supply and barrier construction. Glacio‐isostatic uplift of the outlet sill, faster than sea‐level rise, lifted ELO above the Champlain Sea about 12.5 cal. ka. Shortly after, a hydrological deficit due mainly to a combination of diverted meltwater inflow and dry climate, well known from regional pollen studies, forced the lake into a lowstand. The lowstand stranded the barrier, which remains as evidence of sea level, the farthest inland in eastern North America north of the Gulf of Mexico at the time. The highest palaeo‐washover surface provides a sea‐level index point.

A younger glacial Lake Iroquois in the Lake Ontario basin, Ontario and New York: re-examination of pollen stratigraphy and radiocarbon dating

“…Following the decline of Lake Iroquois, glacial lake waters in the Ontario basin stabilized briefly at the Frontenac, Sydney?, Belleville, and Trenton levels (Mirynech 1962;Muller and Prest 1985) before falling to Early Lake Ontario, confluent with the Champlain Sea in the upper St. Lawrence Valley at about 12 800 cal years BP (Pair et al 1988;Pair and Rodrigues 1993;Anderson and Lewis 2012;Lewis and Todd 2019). As the Sydney level has been contested (Leyland 1984) and is thought instead to be evidence of intermittent, falling water levels (Pair et al 1988), it is portrayed here with a question mark (Fig.…”

Tensile Strength of Cement-Treated Champlain Sea Clay: An Experimental and Numerical Study

“…Lawrence lowlands to the vicinity of city of Ottawa (Lewis & Todd, 2019). The origin of this deposit can be traced to the Wisconsin Ice Sheet of the last ice age that reached its maximum reach around 18,000 to 20,000 years BP (before present) and covered much of present day Hudson Bay area, eastern Canada and northeastern United States.…”

“…The origin of this deposit can be traced to the Wisconsin Ice Sheet of the last ice age that reached its maximum reach around 18,000 to 20,000 years BP (before present) and covered much of present day Hudson Bay area, eastern Canada and northeastern United States. Glacial retreat occurred between 18,000 to 6,000 years BP (Lewis & Todd, 2019) and during this process, a glacial sea known as Champlain Sea covered present day St Lawrence River valley between 12,000 to 10,000 years BP and directly fed into Early Lake Ontario (Quigley, 1980;Lewis & Todd, 2019) (Quigley, 1980).…”

A late-glacial lake-effect climate regime and abundant tamarack in the Great Lakes Region, North America

“…P2early, 12.9-12.5 ka The ARWs indicate that a southern boreal-type climate was established across the EOL-AP by the start of P2early, 12.9 ka, concurrent with increasing lake surface area, the wind interface north of the Lake Ontario basin, and an overall reduction in meltwater flow south of the interface, including the absence of meltwater in ELE (Eschman and Karrow, 1985;Farrand and Drexler, 1985;Pair and Rodrigues, 1993;Webb et al, 2003;Rayburn et al, 2005Rayburn et al, , 2011Anderson and Lewis 2012;Lewis et al, 2012;Watson et al, 2018;Leydet et al, 2018;Lewis and Todd, 2019; Fig. 3B).…”