Stratigraphy, age, and flora of the Southport forest bed, Southeastern Wisconsin

Schneider, Allan F.; Leavitt, Steven W.; Lange, Todd

doi:10.1016/j.jglr.2009.07.003

Cited by 2 publications

(2 citation statements)

References 30 publications

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“…Importantly, the varved unit is underlain by an extensive organic deposit containing plant macrofossils and in situ trees-the remains of a forest that was drowned and buried by a rise in lake level. Elsewhere in the Upper Great Lakes, buried forests have provided key insight into lake level fluctuations, glacial chronology, and paleovegetation composition during the Holocene (Lowell et al 1999;Pregitzer et al 2000;Lewis et al 2005;Hunter et al 2006;Schneider et al 2009). In the present study, we report the first buried forest from the north shore of Lake Superior and one of only a small number of similar deposits known across the Great Lakes basin.…”

Section: Introductionmentioning

confidence: 99%

An 8,900-year-old forest drowned by Lake Superior: hydrological and paleoecological implications

et al. 2010

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Exposures along the lower Kaministiquia River (near Thunder Bay, Ontario, Canada) provide insight into early Holocene lake level fluctuations and paleoenvironmental conditions in the northwestern Lake Superior basin. These exposures show at least two large paleochannels which were downcut into offshore sediments, and were later filled with [2 m of sand, *3 m of rhythmically laminated silt and clay, and *6 m of interbedded silt and sand. Buried by the rhythmically laminated silty clay unit is a wellpreserved organic deposit with abundant plant macrofossils from terrestrial and emergent taxa, including several upright tree trunks. Three AMS radiocarbon ages were obtained on wood and conifer cones from this deposit: 8,135 ± 25 (9,130-9,010 cal), 8,010 ± 25 (9,010-8,780 cal), and 7,990 ± 20 (8,990-8,770 cal) BP. This sequence records an early postglacial high-water phase, followed by the Houghton lowstand, and reflooding of the lower Kaministiquia River Valley. The drop in lake level associated with the Houghton phase forced the ancestral Kaministiquia River to downcut. By *9,100 cal (*8,100) BP, older channels eroded into subaqueous underflow fan deposits in the Thunder Bay area near Fort William Historical Park (FWHP) were abandoned and colonized by a Picea-Abies-Larix forest. Based on stratigraphic data corrected for differential isostatic rebound, the lake was below the Sault Ste. Marie bedrock sill between at least 9,100 cal (8,100) and 8,900 cal (8,000) BP. Shortly after 8,900 cal BP, the lake quickly rose and buried in situ lowland vegetation at FWHP with varved sediments. We argue that this transgression was due to overflow from glacial Lakes Agassiz or Ojibway associated with the retreat of the Laurentide Ice Sheet from the Nakina moraine and/or the Cochrane surge margins in the Hudson Bay Lowlands. A continued rise in lake level after 6,420 ± 20 (7,400 cal) BP at FWHP may record uplift of the North Bay outlet above the Sault Ste. Marie bedrock sill and the onset of the Nipissing transgression in the Lake Superior basin.

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Section: Introductionmentioning

confidence: 99%

An 8,900-year-old forest drowned by Lake Superior: hydrological and paleoecological implications

et al. 2010

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“…According to Lewis (1969), this new phase, the Nipissing II, existed until about 4.0 ka when lake level fell to the level of the Algoma phase. Contemporary and subsequent researchers in the Lake Michigan-Huron and Lake Superior basins added data to improve understanding about the age of these events (e.g., Winkler, 1962;Farrand and Miller, 1968;Lewis, 1970;Larsen, 1974;Gutschick and Gonsiewski, 1976;Cowan, 1978;Monaghan et al, 1986;Lewis and Anderson, 1989;Thompson, 1989;Terasmae, 1979;Timmons et al, 2007;Schneider et al, 2009). Combined, however, these data yield a wide spectrum of ages for the initiation and duration of the Nipissing phase.…”

Section: Introductionmentioning

confidence: 99%

Mid Holocene lake level and shoreline behavior during the Nipissing phase of the upper Great Lakes at Alpena, Michigan, USA

Thompson¹,

Lepper²,

Endres³

et al. 2011

Journal of Great Lakes Research

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Stratigraphy, age, and flora of the Southport forest bed, Southeastern Wisconsin

Cited by 2 publications

References 30 publications

An 8,900-year-old forest drowned by Lake Superior: hydrological and paleoecological implications

An 8,900-year-old forest drowned by Lake Superior: hydrological and paleoecological implications

Mid Holocene lake level and shoreline behavior during the Nipissing phase of the upper Great Lakes at Alpena, Michigan, USA

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