Isostatic rebound and its effects on fish colonization and distribution in the western Lake Superior basin

1994 ◽  
Vol 72 (1) ◽  
pp. 78-86
Author(s):  
S. A. Stephenson ◽  
W. T. Momot
Keyword(s):  
Comparative Study ◽  
Lake Superior ◽  
Mountain Lakes ◽  
Isle Royale ◽  
Lake Agassiz ◽  
Western Basin ◽  
Glacial Retreat ◽  
Isostatic Rebound ◽  
Western Lake ◽  
Large Numbers

Ichthyofaunal surveys of the Huron Mountains and Isle Royale, Michigan, and the Sibley Peninsula, Ontario, allow for both a comparative study of colonization events and the effects of sequential isostatic rebound within a large portion of the western Lake Superior basin. The distribution of some fish species in these areas is the result of catastrophic events related to glacial retreat. The highest Huron Mountain lakes were colonized during channel events occurring shortly after the Marquette readvance began its retreat. Some species present on the Sibley Peninsula were likely carried by overflows from Lake Agassiz. Most lakes within these areas, however, were colonized well after 9700 BP, when large numbers of species had gained entrance to Lake Superior, mainly from Mississippi basin refugia. Several species, presumably because of earlier warming periods, had a wider distribution than they exhibit today. Some colonization of Isle Royale was probably through the straying of a few individuals from these populations. Lake Superior remains a formidable barrier to many species, restricting them to favourable areas within the western basin.

Moraines and late-glacial stratigraphy in central Lake Superior

2020 ◽  
Vol 98 ◽  
pp. 19-35
Author(s):  
Steven M. Colman ◽  
Andy Breckenridge ◽  
Lucas K. Zoet ◽  
Nigel J. Wattrus ◽  
Thomas C. Johnson
Keyword(s):  
Seismic Reflection ◽  
Lake Superior ◽  
Late Glacial ◽  
Laurentide Ice Sheet ◽  
Isle Royale ◽  
Lake Agassiz ◽  
Ice Dynamics ◽  
Glacial Sediments ◽  
Western Lake ◽  
Glacial Lake Agassiz

AbstractSeismic-reflection surveys of the Isle Royale sub-basin, central Lake Superior, reveal two large end moraines and associated glacial sediments deposited during the last cycle of the Laurentide Ice Sheet in the basin. The Isle Royale moraines directly overlie bedrock and are cored with dense, acoustically massive till intercalated down-ice with acoustically stratified outwash. Till and outwash are overlain by glacial varves, a lower red unit and an upper gray unit.The maximum extent of late Younger Dryas-age readvance into the western Lake Superior basin is uncertain, but it was probably controlled by both ice dynamics and climate. Our data indicate that during retreat from the maximum, the ice paused just long enough to construct the outer of the two moraines, >100 m high, and then retreated to the inner moraine, during which time most of the lower glacial-lacustrine sequence (red varves) was deposited. Retreat from the inner moraine coincided with a marked flux of icebergs at the calving margin and a change to gray varves. Rapid retreat may be related to both an influx of meltwater from Glacial Lake Agassiz about 10,500 cal yr BP and retreat of the calving margin down an adverse slope into the Isle Royale sub-basin.

Interpretation of seismic reflection and gravity profile data in western Lake Superior

1994 ◽  
Vol 31 (4) ◽  
pp. 652-660 ◽  
Author(s):  
John L. Sexton ◽  
Harvey Henson Jr.
Keyword(s):  
Fault Zone ◽  
Seismic Data ◽  
Seismic Reflection ◽  
Lake Superior ◽  
Rift System ◽  
Isle Royale ◽  
Midcontinent Rift ◽  
Detachment Faults ◽  
Western Lake ◽  
Midcontinent Rift System

The interpretation of 1047 km of seismic reflection data collected in western Lake Superior is presented along with reflection traveltime contour maps and gravity models to understand the overall geometry of the Midcontinent Rift System beneath the lake. The Douglas, Isle Royale, and Keweenaw fault zones, clearly imaged on the seismic profiles, are interpreted to be large offset detachment faults associated with initial rifting. These faults have been reactivated as reverse faults with 3–5 km of throw. The Douglas Fault Zone is not directly connected with the Isle Royale Fault Zone. The seismic data has imaged two large basins filled with more than 22 km of middle Keweenawan pre-Portage Lake and Portage Lake volcanic rocks and up to 8 km of upper Keweenawan Oronto and Bayfield sedimentary rocks. These basins persisted throughout Keweenawan time and are separated by a ridge of Archean rocks and a narrow trough bounded by the Keweenaw Fault Zone to the south. Another fault zone, herein named the Ojibwa fault zone, previously interpreted as the northeastern extension of the Douglas Fault Zone, has been reinterpreted as a reverse fault that closely follows the ridge of Archean rocks. Previous researchers have stated that neighboring segments of the rift display alternating polarity of basins associated with large detachment faults. Accommodation zones have been previously interpreted to exist between rift segments; however, the seismic data do not image a clearly identifiable accommodation zone separating the two basins in western Lake Superior. Thus, the seismic profile may lie directly above the pivot of a scissors-type accommodation fault zone, there is no vertical offset associated with the zone, or the zone does not exist. Seismic data interpretations indicate that application of a simple alternating polarity basin – accommodation zone model is an oversimplification of the complex geological structures associated with the Midcontinent Rift System.

Genetic diversity and distribution of Sarracenia purpurea (Sarraceniaceae) in the western Lake Superior basin

2006 ◽  
Vol 84 (2) ◽  
pp. 235-242 ◽  
Author(s):  
Jennifer M. Karberg ◽  
Margaret R. Gale
Keyword(s):  
Genetic Diversity ◽  
Demographic Data ◽  
Lake Superior ◽  
Plant Morphology ◽  
Morphological Diversity ◽  
Morphological Characters ◽  
Sarracenia Purpurea ◽  
Western Basin ◽  
Seed Sources ◽  
Western Lake

Restoring plant populations requires an understanding of plant morphological adaptation to site locations and population genetic diversity and relatedness. This study examined the genetic and morphological diversity of Sarracenia purpurea L. within the natural fragmentation of western Lake Superior. Populations of S. purpurea were compared among three locations: Isle Royale National Park, the Keweenaw Peninsula, Michigan, USA, and Sleeping Giant Provincial Park, Ontario, Canada. Analysis of genetic and demographic data showed Canadian populations to be less robust with smaller plant sizes. Canadian populations were also slightly distinct genetically. Overall genetic diversity appears moderate (H = 0.30–0.36) and populations genetically similar. Analysis of molecular variance showed only 3.83% of variation among the three locations (p = 0.0049). Fragmentation did not have a distinguishable effect on genetic diversity and morphological characters but the limestone bedrock geology of the Canadian region may be starting to influence plant morphology and genetic differentiation. This indicates that restoration can take place within the western basin of Lake Superior using a variety of seed sources but regional geology may influence observed plant morphology.

Predation by Rainbow Smelt (Osmerus mordax) on Lake Herring (Coregonus artedii) in Western Lake Superior

1978 ◽  
Vol 35 (11) ◽  
pp. 1457-1463 ◽  
Author(s):  
James H. Selgeby ◽  
Wayne R. MacCallum ◽  
Donald V. Swedberg
Keyword(s):  
Lake Superior ◽  
Commercial Production ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Predator Prey ◽  
Western Lake ◽  
Large Numbers ◽  
Coregonus Artedii ◽  
Historical Levels ◽  
Lake Herring

The stock of lake herring (Coregonus artedii) in the Apostle Islands (Wisconsin) region of western Lake Superior has diminished severely during the past 30 yr, and predation by rainbow smelt (Osmerus mordax) on herring larvae has been considered a possible cause of this decline. In contrast, the herring stock in Black Bay, 160 km to the northeast, has remained nearly stable despite the presence of large numbers of smelt and high commercial production of herring. Predator–prey interactions were studied in both areas during 1974. Herring larvae and smelt were about 120 and 3 times as dense, respectively, in Black Bay as in the Apostle Islands region. Substantial predation by smelt on young herring was evident in Black Bay, where 17% of 1195 smelt stomachs examined contained herring larvae. From calculations of the relative densities of the two species, and of the daily ration of the predators, we estimated that smelt consumed 3.3–11% of the herring larvae. Nevertheless, the herring stocks have sustained average historical levels of commercial production. In contrast, no herring larvae were found in the stomachs of 1711 smelt collected in the Apostle Islands region. We conclude that predation by smelt on herring larvae is not the major factor controlling or suppressing herring stocks in either region. Key words: lake herring, rainbow smelt, predation, Lake Superior

Seismic Reflection Study of Recessional Moraines beneath Lake Superior and Their Relationship to Regional Deglaciation

1982 ◽  
Vol 17 (2) ◽  
pp. 173-190 ◽  
Author(s):  
C. W. Landmesser ◽  
T. C. Johnson ◽  
R. J. Wold
Keyword(s):  
Seismic Reflection ◽  
Lake Superior ◽  
Lacustrine Sediments ◽  
Acoustic Properties ◽  
Glacial Lake ◽  
Glacial Retreat ◽  
Lake Evolution ◽  
Western Lake ◽  
Seismic Reflection Profiles ◽  
Basal Till

AbstractApproximately 8000 km of continuous seismic reflection profiles throughout Lake Superior were examined for evidence of recessional moraines and other ice-margin deposits associated with the retreat of late Wisconsin ice. These features are correlated with the record of glacial-lake evolution in western Lake Superior. An offlapping sequence of glacial and glacial-lacustrine sediments overlying bedrock is recognized in west-central Lake Superior that is progressively younger to the northeast. The sequence underlies more recent glaical-lacustrine and postglacial sediments. Four facies are recognized on the basis of geomorphologic and acoustic properties and are interpreted to represent a southwest-to-northeast assemblage of: proglacial stratified drift (facies A), drift in major end moraines (facies B), till deposited as glacial retreat resumed, or possibly late-stage ablation till (facies C), and basal till (facies D). The prominent moraines of facies B are unusually thick and are believed to mark the ice-margin shorelines of successive major proglacial lakes that formerly occupied parts of western Lake Superior. The moraines are tentatively correlated with Glacial Lake Duluth (unit 1), Glacial Lake Washburn (unit 2), and Glacial Lake Beaver Bay (unit 3), the most prominent of lakes drained via the progressively lower outlets via the Moose Lake/ Brule-St. Croix Rivers, the Huron Mountains, and the Au Train-Whitefish regions, respectively.

An analysis of the late glacial lake levels within the western Lake Superior basin based on digital elevation models

2013 ◽  
Vol 80 (3) ◽  
pp. 383-395 ◽  
Author(s):  
Andy Breckenridge
Keyword(s):  
Lake Michigan ◽  
Digital Elevation Models ◽  
Lake Superior ◽  
Late Glacial ◽  
Glacial Lake ◽  
Lake Levels ◽  
Lake Agassiz ◽  
Western Lake ◽  
Digital Elevation ◽  
Ice Retreat

This study establishes a detailed lake-level history for the Lake Superior basin by mapping strandlines from 10-m and 3-m digital elevation models. There are 24 levels above the mid-Holocene Nipissing level, and elevations increase along a direction of 23.1° due to post-glacial rebound. The highest level, the Epi-Duluth, is steeper than subsequent levels and may pre-date the Lake View ice advance into the western Lake Superior basin at the end of the Younger Dryas stade. The most prominent level is the Duluth, ca. 10,800 cal yr BP. Ice retreat exposed successively lower outlets, routing overflow to the Lake Michigan and Huron basins. By 10,600 cal yr BP, lake levels in the western Superior basin had dropped almost 200 m. This transformative period is complicated by multiple basin-wide events: the influx of glacial Lake Agassiz overflow, the creation of three sub-aqueous moraines, and a red to gray color transition in basin sediments. A later drawdown event has been hypothesized to have initiated the 9300 cal yr BP cooling event, but this flood was much smaller than estimated previously. If freshwater triggered the 9300 cal yr BP event, the source of the water must have been Lake Agassiz, not Lake Superior.

Estimating Sediment and Nutrient Loads in Four Western Lake Superior Streams

2014 ◽  
Vol 50 (5) ◽  
pp. 1138-1154 ◽  
Author(s):  
Elaine M. Ruzycki ◽  
Richard P. Axler ◽  
George E. Host ◽  
Jerald R. Henneck ◽  
Norman R. Will
Keyword(s):  
Lake Superior ◽  
Nutrient Loads ◽  
Western Lake

The effect of a flood pulse on the water column of western Lake Superior, USA

2014 ◽  
Vol 40 (2) ◽  
pp. 455-462 ◽  
Author(s):  
Elizabeth C. Minor ◽  
Brandy Forsman ◽  
Stephanie J. Guildford
Keyword(s):  
Water Column ◽  
Lake Superior ◽  
Flood Pulse ◽  
Western Lake

Paleohydrology of the upper Laurentian Great Lakes from the late glacial to early Holocene

2009 ◽  
Vol 71 (3) ◽  
pp. 397-408 ◽  
Author(s):  
Andy Breckenridge ◽  
Thomas C. Johnson
Keyword(s):  
Great Lakes ◽  
Lake Michigan ◽  
Lake Superior ◽  
Late Glacial ◽  
Lake Huron ◽  
Michigan Basin ◽  
Great Lakes Basin ◽  
Lake Agassiz ◽  
Sharp Drop ◽  
Freshwater Fluxes

AbstractBetween 10,500 and 9000 cal yr BP, δ18O values of benthic ostracodes within glaciolacustrine varves from Lake Superior range from − 18 to − 22‰ PDB. In contrast, coeval ostracode and bivalve records from the Lake Huron and Lake Michigan basins are characterized by extreme δ18O variations, ranging from values that reflect a source that is primarily glacial (∼ − 20‰ PDB) to much higher values characteristic of a regional meteoric source (∼ − 5‰ PDB). Re-evaluated age models for the Huron and Michigan records yield a more consistent δ18O stratigraphy. The striking feature of these records is a sharp drop in δ18O values between 9400 and 9000 cal yr BP. In the Huron basin, this low δ18O excursion was ascribed to the late Stanley lowstand, and in the Lake Michigan basin to Lake Agassiz flooding. Catastrophic flooding from Lake Agassiz is likely, but a second possibility is that the low δ18O excursion records the switching of overflow from the Lake Superior basin from an undocumented northern outlet back into the Great Lakes basin. Quantifying freshwater fluxes for this system remains difficult because the benthic ostracodes in the glaciolacustrine varves of Lake Superior and Lake Agassiz may not record the average δ18O value of surface water.

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