Superior Basin Research Articles

Geoarchaeology and late glacial landscapes in the western lake superior region, Central North America

AbstractThe transition from full glacial to interglacial conditions along the southern margin of the Laurentide ice sheet resulted in dramatic changes in landscapes and biotic habitats. Strata and landforms resulting from the Wisconsin Episode of glaciation in the area directly west of Lake Superior indicate a context for late Pleistocene biota (including human populations) connected to ice margins, proglacial lakes, and postglacial drainage systems. Late Glacial landscape features that have the potential for revealing the presence of Paleoindian artifacts include abandoned shorelines of proglacial lakes in the Superior and Agassiz basins and interior drainages on deglaciated terrains. The linkage between Late Pleistocene human populations and Rancholabrean fauna has yet to be demonstrated in the western Lake Superior region, although isolated remains of mammoth ( Mammuthus) have been documented, as well as fluted points assigned to Clovis, Folsom, and Holcombe‐like artifact forms. Agate Basin and Hell Gap (Plano‐type) artifacts also imply the presence of human groups in Late Glacial landscapes associated with the Agassiz and Superior basins. © 2007 Wiley Periodicals, Inc.

Constraints on paleolake levels, spillways and glacial lake history, north-central Ontario, Canada

The recognition of ice-marginal deltas constructed during the formation of the Nakina II moraine and a previously unrecognized spillway, in the vicinity of Longlac, northern Ontario, indicates that existing concepts of ancestral lake level history and drainage systems in the Lake Superior–Lake Nipigon region is inadequate. Based on isostatically corrected digital elevation maps, ice-marginal deltas of the Nakina II moraine probably formed at the level of glacial Lake Minong, most likely Minong III, and not glacial Lake Nakina as has been commonly suggested. In addition, the presence of a spillway near Longlac indicates that lake water drained southward through the Mullet Outlet–Pic River system immediately following ice-marginal retreat from the Nakina II moraine and not eastward as previously proposed. Architectural-element analysis of exposures within the spillway indicates hyperconcentrated outbursts of meltwater produced thick channel-fill elements during flood conditions with peak-velocities exceeding 3 m/s. Subsequent retreat of ice from the Pic River valley to the east, may have allowed waters of Lake Agassiz, Lake Barlow–Ojibway, or both, to drain into post-Minong lake levels in the Lake Superior basin. These findings place major constraints on previously proposed concepts of northeastern or eastern outlets of Lake Agassiz.

The Duck Lake Site and Implications for Late Archaic Copper Procurement and Production in the Southern Lake Superior Basin

Few sites relating to Archaic procurement of copper have been archaeologically investigated in the southern part of the Lake Superior basin. The Duck Lake site, located in the Ontonagon River watershed of Michigan's Upper Peninsula, is within the source area for native copper. Investigations at this site reveal a field camp consisting of one or more occupations by Late Archaic groups. Lithic analysis demonstrates a strong reliance on non-local raw materials, and suggests a degree of residential mobility within a region known to the occupants. Lithic material was obtained through embedded procurement and exchange with more distant groups. Copper likely entered the early Late Archaic exchange system in the Midwest through frequent interactions and trade between groups, and appears consistent with a down-the-line model of exchange.

Testing the Lake Agassiz meltwater trigger for the Younger Dryas

Meltwater drainage from glacial Lake Agassiz has been implicated for nearly 15 years as a trigger for thermohaline circulation changes producing the abrupt cold period known as the Younger Dryas. On the basis of initial field reconnaissance to the lake's proposed outlets, regional geomorphic mapping, and preliminary chronological data, an alternative hypothesis may be warranted.Should ongoing data collection continue to support preliminary results, it could be concluded that Lake Agassiz did not flood catastrophically into the Lake Superior basin preceding the Younger Dryas (Figure 1). All preliminary findings imply a retreating ice sheet margin approximately 1000 years younger than previously thought, which would have blocked key meltwater corridors at the start of the Younger Dryas.

Geophysicists

Meltwater drainage from glacial Lake Agassiz has been implicated for nearly 15 years as a trigger for thermohaline circulation changes producing the abrupt cold period known as the Younger Dryas. On the basis of initial field reconnaissance to the lake's proposed outlets, regional geomorphic mapping, and preliminary chronological data, an alternative hypothesis may be warranted.Should ongoing data collection continue to support preliminary results, it could be concluded that Lake Agassiz did not flood catastrophically into the Lake Superior basin preceding the Younger Dryas (Figure 1). All preliminary findings imply a retreating ice sheet margin approximately 1000 years younger than previously thought, which would have blocked key meltwater corridors at the start of the Younger Dryas.

Changes in the human migration patterns in the Maramures region (Romania - Ukraine)

In this paper we discuss the changes in human migration patterns in the Maramures region during the last decade. The term “Maramures region” refers to the historical Maramures County, in the Northern sector of the South-Eastern Carpathians, encompassing the superior basin of the Tisa river. After WWI, the region was divided into two distinct sectors, presently belonging to Romania and Ukraine. However, the unitary natural environment, a common history and their peripheral position justify a unified approach to the issue of human migration patterns. Before 1990, due to specific human and natural factors, the mobility pattern was characterized by seasonal agricultural work migrations. Due to the opening of new opportunities after 1990, internal agricultural migration was transformed into international work migration. Herein, we present statistical data acquired through fieldwork for two villages in the Romanian sector: Barsana and Sapanta. International migration rates in 2001 were, correspondingly, 6.4% and 4.8%. With respect to migration directions, the ease of communication in the destination country for lower educated persons plays a vital role.

Alternative routing of Lake Agassiz overflow during the Younger Dryas: new dates, paleotopography, and a re-evaluation

Overflow from glacial Lake Agassiz has been implicated in affecting late-glacial ocean circulation and climate. The timing of the diversion of Lake Agassiz overflow away from its southern routing (to the Gulf of Mexico) correlates closely with the Younger Dryas ca 11–10 14C ka. New models of paleotopography in the eastern outlet region of Lake Agassiz, adjusted for differential isostatic rebound, show that overflow to the Superior basin would have occurred when the lake formed its Herman, Norcross, and Tintah beaches, just after ∼10.9 14C ka, if the Laurentide Ice Sheet (LIS) had retreated from the Thunder Bay, Ontario, region by that time. However, the absence of coarse flood deposits normally associated with large overflows, plus the morphology of possible overflow channels in the Thunder Bay region, suggest that Agassiz overflow may not have been routed into the Great Lakes during the Younger Dryas, as previously believed. In addition, non-carbonate radiocarbon dates in the Thunder Bay area are all younger than 10 14C ka, suggesting that this area may not have been deglaciated until after the Younger Dryas, thus preventing Lake Agassiz overflow through this area. An alternative route of overflow from Lake Agassiz during the Younger Dryas could have been through the northwestern (Clearwater) outlet to the Arctic Ocean, although all research to date shows that this region was covered by ice until ∼10 14C ka. On the other hand, it is possible that older and coarser overflow sediment may now lie buried beneath finer deposits associated with the 10 14C ka Marquette readvance of the LIS, which ponded waters in valleys between Lake Agassiz and Lake Superior, or that eastward overflow in this area was not catastrophic.

Relationship of stream flow regime in the western Lake Superior basin to watershed type characteristics

To test a conceptual model of non-linear response of hydrologic regimes to watershed characteristics, we selected 48 second- and third-order study sites on the North and South Shores of western Lake Superior, MN (USA) using a random-stratified design based on hydrogeomorphic region, fraction mature forest, and fraction watershed storage (lake+wetland area/watershed area). We calculated several commonly used hydrologic indices from discharge and velocity estimates, including daily flow indices, overall flood indices, low flow variables, and ratios or ranges of flow percentiles reflecting the nature of cumulative frequency distributions. Four principal components (PCs) explained 85.9 and 88.6% of the variation of flow metrics among second- and third-order stream sites, respectively. Axes of variation corresponded to a runoff vs. baseflow axis, flow variability, mean flow, and contrasts between flood duration and frequency. Analysis of velocity metrics for third-order streams yielded four PCs corresponding to mean or maximum velocity, Froude number, and inferred shear velocity, as well as spate frequencies vs. intervals associated with different velocity ranges. Using discriminant function analysis, we could discriminate among watershed classes based on region, mature forest, or watershed storage as a function of flow metrics. For second-order streams, median flow ( Qs 50) increased as watershed storage increased. North Shore streams showed a more skewed distribution and greater spread of discharge values than did South Shore streams for both stream orders, while third-order North Shore streams exhibited a higher frequency of spates. Independent of regional differences, loss of mature forest increased the range of variation between baseflow and peak flows, and depressed baseflow. Consistent with our initial model for watershed classification, Classification and Regression Tree (CART) analysis confirmed significant thresholds of change in flow metrics averaging between 0.506 and 0.636 for fraction mature forest and between 0.180 and 0.258 for fraction watershed storage.

PREHISTORIA DEL PERÍODO FORMATIVO EN LA CUENCA ALTA DEL RÍO SALADO (REGIÓN DEL LOA SUPERIOR)

The systematization on chronology, rock art, landscape, and settlement pattern carried out at the upper Salado river in the Loa superior basin have produced important advance in the understanding of the regional prehistory. This is particularly true for the Formative and Early Intermediate periods as multiple archaeological settlements have been identified, supported by more than forty archaeometric from 1.400 BC to AD 900. These results have permitted to go ahead in the comprehension of the subsistence and settlement systems of the local populations, and to understand their entailment with the complex formative processes that are developing in the Circumpunean. In this paper, a specifically cultural/historical period frame for the Formative period is proposed throughout a systematization of settlement and chronology's new information in this sub-region, updating previous chronological data and integrating the whole archaeological information.

REGION, LANDSCAPE, AND SCALE EFFECTS ON LAKE SUPERIOR TRIBUTARY WATER QUALITY1

ABSTRACT: In 1998 and 1999, third‐order watersheds in high mature forest (HMF) and low mature forest (LMF) classes were selected along gradients of watershed storage within each of two hydrogeomorphic regions in the Lake Superior Basin to evaluate threshold effects of storage on hydrologic regimes and watershed exports. Differences were detected between regions (North and South Shore) for particulates, nutrients, and pH, with all but silica values higher for South Shore streams (p < 0.05). Mature forest effects were detected for turbidity, nutrients, color, and alkalinity, with higher values in the LMF watersheds, that is, watersheds with less that 50 percent mature forest cover. Dissolved N, ammonium, N:P, organic carbon, and color increased, while suspended solids, turbidity, and dissolved P decreased as a function of storage. Few two‐way interactions were detected between region and mature forest or watershed storage, thus threshold based classification schemes could be used to extrapolate effects across regions. Both regional differences in water quality and those associated with watershed attributes were more common for third‐order streams in the western Lake Superior drainage basin as compared with second‐order streams examined in an earlier study. Use of ecoregions alone as a basis for setting regional water quality criteria would have led to misinterpretation of reference condition and assessment of impacts in the Northern Lakes and Forest Ecoregion.

Landscape Character and Fish Assemblage Structure and Function in Western Lake Superior Streams: General Relationships and Identification of Thresholds

As part of a comparative watershed project investigating land-cover/land-use disturbance gradients for streams in the western Lake Superior Basin, we examined general relationships between landscape character and fish assemblage structure and function. We also examined the shape of those relationships to identify discontinuity thresholds where small changes in landscape character were associated with marked shifts in the fish assemblages. After completing a geographic analysis of second- and third-order watersheds in the western Lake Superior drainage, we randomly selected 48 streams along mature forest and watershed storage gradients in 2 hydrogeomorphic regions as our study sites. During the summers of 1997 and 1998, we used electrofishing to sample fish assemblages from each stream. Each of the landscape factors was significantly associated with fish assemblage structure and function based on analysis of covariance. Watershed storage was related to the greatest number of fish assemblage characteristics, but hydrogeopmorphic region and mature forest cover were strongly associated as well. The hydrogeomorphic region also mediated relationships between watershed character and fish assemblages. Discontinuity thresholds for our fish assemblages averaged 11% for watershed storage and 50% for watershed mature forest cover based on piecewise regression analysis. Although many of the landscape-fish relationships might have been manifest through effects on in-stream habitat, our results highlight the importance of management and land-use planning decisions at the watershed and landscape scales.

A Comparison of Organochlorine Contaminant Levels, on a Lipid Basis, in Sea Lamprey Larvae from Mad River, Lake Huron Basin and Michipicoten River, Lake Superior Basin (1960-1976)

Abstract Organochlorine concentrations, on a lipid basis, were determined for formalin-preserved sea lamprey larvae, collected between 1960 and 1976 in the Mad River, Lake Huron basin, and compared with previously published data from Michipicoten River, Lake Superior basin. Although the ages of the lamprey specimens between the two lake basins were different, their lipid content, expressed as a percentage of dry body weight, was comparable. Despite the fact that the samples came from areas separated by about 550 km and with different land use (heavily forested area with mining activities but little agriculture for Lake Superior versus poultry farming, agricultural, urban and military uses for Lake Huron), no statistically significant differences were found for most organochlorine residue concentrations (Σaldrin, ΣCB, Σchlordane, ΣDDT, Σendosulfan and ΣPCB) between the two lake basins. The exception was ΣHCH, which was significantly lower in Lake Huron due to the absence of a high-level period observed in 1970 to 1975 in Lake Superior samples. Additionally, no differences were found between the relative concentrations of the various DDT metabolites between the two basins, but significantly higher relative concentrations of higher chlorinated PCBs (hexa to decachloro congeners) were found in Lake Huron samples. This study demonstrates the usefulness of formalin-preserved museum material to conduct retrospective contaminant analyses. However, given that certain amounts of contaminants were also found in the preservative solution, consideration of these levels is important to properly interpret the results.

Paleotopographic reconstructions of the eastern outlets of glacial Lake Agassiz

Paleotopographic reconstructions of the eastern outlets of glacial Lake Agassiz provide a foundation for understanding the complex manner in which terrain morphology controlled the routing of overflow through the eastern outlets during the lake's Nipigon Phase (ca. 9400–8000 14C years BP) and for understanding the causes of outlet-driven declines in lake level during that period. Although flow paths across the divide between the Agassiz and Nipigon basins were numerous, eastward releases from Lake Agassiz to glacial Lake Kelvin (modern Lake Nipigon) were channeled downslope into a relatively small number of major channels that included the valleys of modern Kopka River, Ottertooth Creek, Vale Creek, Whitesand River, Pikitigushi River, and Little Jackfish River. From Lake Kelvin, these waters overflowed into the Superior basin. The numerous lowerings in lake level between stages of the Nipigon Phase, controlled by topography and the position of the retreating southern margin of the Laurentide Ice Sheet, had magnitudes of between 8 and 58 m, although some of these drawdowns may have occurred as multiple individual events that could have been as small as several metres. The total volumes of water released in association with these drops were as great as 8100 km3, and for all Nipigon stages were probably between about 140 and 250 km3 per metre of lowering. The topographic reconstructions demonstrate that Lake Agassiz occupied the area of glacial Lake Nakina (located northeast of modern Lake Nipigon) by the The Pas stage (ca. 8000 14C years BP) and that Lake Agassiz drainage through the Nipigon basin to the Great Lakes ended before the succeeding Gimli stage.

Effects of hydrogeomorphic region, catchment storage and mature forest on baseflow and snowmelt stream water quality in second‐order Lake Superior Basin tributaries

SUMMARY1. In this study we predict stream sensitivity to non‐point source pollution based on the non‐linear responses of hydrological regimes and associated loadings of non‐point source pollutants to catchment properties. We assessed two hydrologically based thresholds of impairment, one for catchment storage (5–10%) and one for mature forest (<50% versus >60% of catchment in mature forest cover) across two different hydrogeomorphic regions within the Northern Lakes and Forest (NLF) ecoregion: the North Shore [predominantly within the North Shore Highlands Ecological Unit] and the South Shore (predominantly within the Lake Superior Clay Plain Ecological Unit). Water quality samples were collected and analysed during peak snowmelt and baseflow conditions from 24 second‐order streams grouped as follows: three in each region × catchment storage × mature forest class.2. Water quality was affected by a combination of regional influences, catchment storage and mature forest. Regional differences were significant for suspended solids, phosphorus, nitrogen: phosphorus ratios, dissolved organic carbon (DOC) and alkalinity. Catchment storage was significantly correlated with dissolved silica during the early to mid‐growing season, and with DOC, specific conductance and alkalinity during all seasons. Total nitrogen and dissolved nitrogen were consistently less in low mature forest than in high mature forest catchments. Catchment storage interacted with the influence of mature forest for only two metrics: colour and the soluble inorganic nitrogen : phosphorus ratio.3. Significant interaction terms (region by mature forest or region by storage) suggest differences in regional sensitivity for conductance, alkalinity, total organic carbon, and colour, as well as possible shifts in thresholds of impact across region or mature forest class.4. Use of the NLF Ecoregion alone as a basis for setting regional water quality criteria would lead to the misinterpretation of reference condition and assessment of condition. There were pronounced differences in background water quality between the North and South Shore streams, particularly for parameters related to differences in soil parent material and glacial history. A stratified random sampling design for baseflow and snowmelt stream water quality based on both hydrogeomorphic region and catchment attributes improves assessments of both reference condition and differences in regional sensitivity.

Modification of a correlation-based circulation pattern classification to reduce within-type variability of temperature and precipitation

When a correlation-based circulation pattern classification was applied to daily 700 hPa heights for 25 summer seasons, and the circulation types were related to surface temperature and precipitation for the Lake Superior basin, within-type variability was found to be high. Regarding temperature, the difference between warm and cold days of a type is a positive height anomaly centred to the east of the lake, which is very similar to the height anomaly for winter temperatures identified in an earlier study. The difference between wet and dry days of a type is a pattern quite unlike that for temperature. It is a dipole pattern consisting of a negative anomaly to the northwest of the lake and a positive anomaly to the east and southeast. These small-scale circulation components were missed by the correlation-based classification because they are much smaller than the differences in height between circulation types. Regression models, relating monthly mean temperature anomalies to circulation type frequencies, produced results comparable to those obtained for winter temperature. For precipitation, the variance explained by the regression models is only half that obtained for temperature. Two approaches were used to reduce within-type variability and to improve the regression results: the division of the first few circulation types into warm/cold and wet/dry subtypes on the basis of differences in 700 hPa vorticity (an approach introduced in the earlier paper), and a modified correlation-based circulation pattern classification. The modification consisted of raising the correlation threshold for a few selected grid-points to capture the small-scale circulation component and also, of lowering the threshold for the comparison between maps and map sectors in order to minimize the number of unclassified days. Of the two approaches used to reduce within-type variability, the modified classification scheme produced superior results. In particular, the variance in precipitation explained by the regression models is about 30% higher than that achieved using vorticity to create subtypes. Copyright © 2000 Royal Meteorological Society

Spatial Distribution of Mercury and Organochlorine Contaminants in Great Lakes Sea Lamprey ( Petromyzon marinus)

Adult sea lamprey ( Petromyzon marinus) were collected during their spawning migration in streams entering each of the Great Lakes, except Lake Michigan. Skinless muscle tissue samples were analyzed for a range of organochlorine contaminants including p,p’-DDE, total PCB, toxaphene, and mercury. Concentrations of p,p’-DDE and PCBs were above the detection limit of 0.002 μg/g in all samples. Levels of total toxaphene in some individuals from Lake Superior were above recent Health Canada consumption advisory limits of 0.2 μg/g for fish. PCBs and ΣDDT concentrations in some lamprey tissue samples from the Lake Ontario basin exceeded limits for unrestricted human consumption. Mercury concentrations were highest in lamprey from the Lake Superior basin. Mercury levels were above the 0.5 μg/g Canada Health Protection Guideline for consumption in 75% of all the lamprey muscle tissue samples analyzed. Comparison of organic contaminant levels for lamprey muscle tissue samples and whole lake trout ( Salvelinus namaycush) collected from the same lakes showed patterns of contaminant accumulation that were similar within each lake for both species. Mercury concentrations were up to 10 times higher in lamprey muscle tissue samples than whole lake trout sampled from the same lake. Lamprey display a differential ability to accumulate mercury versus organochlorines. By understanding these relationships for different classes of contaminants, it may be possible to utilize lamprey as a future alternate to lake trout as an indicator species to track spatial and temporal contaminant trends in the Great Lakes.

Wonderful power: the story of ancient copper working in the Lake Superior Basin

Wonderful power: the story of ancient copper working in the Lake Superior Basin

Application of Non-hierarchically Clustered Circulation Components to Surface Weather Conditions: Lake Superior Basin Winter Temperatures

An S-mode principal component analysis was applied to the correlation and covariance matrices of a 700 hPa height window centered over eastern North America. The first five components were retained and rotated. K-means clustering algorithm was applied to the four solutions to generate 22 circulation types for each. Regression models were built, relating monthly mean temperature anomalies to monthly circulation type frequencies. The results were compared to those obtained in an earlier study using a correlation-based approach to classify the same data set. It was found that i) the amount of within-type variability is comparable for the two and that ii) the difference between cold and warm days of a circulation type is for both classification approaches an anomaly located to the east of the lake. A detailed analysis of this difference indicated that some information is contained in the scores for the first five principal components (and could therefore be used to improve the regression results) but that some is contained in the higher order components and was thus lost. Differences in the PC scores between warm and cold days were used to divide the circulation types into warm and cold subtypes. This improved the regression results but the best results were still inferior to those that had been obtained with the correlation-based classification.

Age verification of the Lake Gribben forest bed and the Younger Dryas Advance of the Laurentide Ice Sheet

Analysis of nine wood samples from the Lake Gribben forest bed near Lake Gribben, Michigan, yielded a combined age of 10 025 ± 100 14C years BP, which confirms and refines prior age estimates for the bed. The stratigraphic position of these samples below a prograding ice-contact fan indicates the time that a glacial margin reached the southern edge of the Lake Superior basin. Geomorphic tracing and correlation of associated deposits indicate that a contemporaneous margin extended almost 1000 km from Duluth, Minnesota, across the Lake Superior basin to North Bay, Ontario. Along the southern shore of Lake Superior ice-margin expansion began during and ended at the close of the Younger Dryas. A surging glacier system would not produce a nearly linear moraine system across both a major basin (Lake Superior) and a major upland (Abitibi Upland). Therefore, we attribute this advance of the Laurentide Ice Sheet to climatic forcing of the Younger Dryas event.

Nitrogen Mineralization in a Mature Boreal Forest, Isle Royale, Michigan

AbstractThe 115‐ha boreal Wallace Lake watershed, located on Isle Royale in the Lake Superior Basin, receives moderate anthropogenic atmospheric N inputs (3 kg ha−1 yr−1). Ecosystem response to atmospheric N inputs is, in part, determined by internal production and consumption of this limiting nutrient. The objectives of this 2‐yr study on plots dominated by birch, spruce, or alder were to quantify forest floor and surface soil net and gross N mineralization rates, and examine potential effects of changes in temperature and moisture on these processes. Gross N mineralization rates were 23 times net mineralization rates, and increased with forest floor/soil temperature and moisture. Substrate quality was a likely factor in higher gross mineralization rates beneath birch and spruce. Ammonium immobilization increased with forest floor/soil temperature and moisture. Higher net N mineralization rates beneath alder resulted from lower microbial immobilization rather than greater gross N mineralization. The greatest differences between gross N mineralization and immobilization occurred in early summer. Ammonium immobilization averaged 62% of gross N mineralization. Net and gross nitrification rates differed by vegetation type, were highest in spring and fall, and increased with moisture. Gross nitrification was 19 times net nitrification rates. Nitrate immobilization increased with soil moisture, and equalled or exceeded gross nitrification. Net and gross N mineralization or nitrification rates were not correlated. Seasonal variation in forest floor and surface soil N cycling coupled with high ecosystem retention of precipitation N inputs suggest streamwater N concentrations and output reflect trends in soil processes.