...are expressed landward of this barrier. Two Vibracores were taken from the lake in February 2000 and contain pebbly sand, sand, buried soils, marl, peat, and sandy muck. It is suggested here that fluctuations in the level of Lake Michigan are reflected in Silver Lake since the Chippewa low phase, and possibly at the end of the Algonquin phase. An age of 12,490 B.P. (10,460[+ or -]50 [.sup.14]C yrs B.P.) on wood from buried Entisol may record the falling Algonquin phase as the North Bay outlet opened. A local perched water table is indicated by marl deposited before 7,800 B.P. and peat between 7,760-7,000 B.P. when Lake Michigan was at the low elevation Chippewa phase. Continued deepening of the lake is recorded by the transition from peat to sandy muck at 7,000 B.P. in the deeper core, and with the drowning of an Inceptisol nearly 3 m higher at 6,410 B.P. in the shallower core. A rising groundwater table responding to a rising Lake Michigan base level during the Nipissing transgression, rather than a response to mid-Holocene climate change, explains deepening of Silver Lake. Sandy muck was deposited continually in Silver Lake between Nipissing and modern time. Sand lenses within the muck are presumed to be eolian in origin, derived from sand dunes advancing into the lake on the western side of the basin.

INTRODUCTION

Qualitative analysis of former Lake Michigan embayments along the western coastline of the Lower Peninsula of Michigan relied upon geomorphic principles (e.g., Scott and Dow 1937). With only relative dating control, the absolute age of specific landforms and lake stages were not known. This paper presents preliminary results from coring in Silver Lake, Michigan (Figures 1 and 2), that establish a chronology for the Silver Lake embayment. The initial intent of the coring was to establish a chronological framework for the dunes on the west side of Silver Lake by dating loess within lacustrine sediment; but much to our surprise, instead of loess, we encountered buried soils, peat, and marl (Loope and Fisher 2000). These sediments indicate that the hydrological conditions within the Silver Lake basin have varied considerably since deglaciation and are the focus of this paper. We also test the hypothesis that captured lakes along the Lake Michigan coastline preserve records of fluctuating late Pleistocene and Holocene levels of Lake Michigan.

[FIGURE 1 OMITTED]

Regional Deglaciation and Proglacial Lakes

During recession of the Michigan Lobe of the Laurentide Ice Sheet~14,000 B.P., glacial Lake Chicago was impounded between the ice margin and the Valparaiso Moraine, the later making up the subcontinental drainage divide. The Chicago outlet, cut to bedrock through the Valparaiso Moraine, controlled lake level during both the Glenwood and Calumet phases of Lake Chicago (see review by Hansel et al. 1985) when the glacier was south of the Straits of Mackinac. The Calumet level, dated between 11.8 and 11.2 ka [.sup.14]C yrs B.P. (Hansel et al. 1985), was controlled by the Chicago outlet when ice again covered the Straits of Mackinac at the northern end of Lake Michigan. After the Calumet phase, the Kirkfield phase in the Michigan basin became confluent with the main level of Lake Algonquin in the Huron basin. Because strand lines are not abundant along Lake Michigan, some have suggested that the Kirkfield water plane lay below modern lake level. Hansel et al. (1985) conclude that the elevation of the Algonquin phase in the Lake Michigan basin (i.e., Kirkfield) lay below the elevation of the Nipissing phases at the southern end of Lake Michigan when the Fenelon Falls outlet in Ontario was open. Recently however, Capps (2002) further documents a strandline in northwestern Indiana between the Calumet and Nipissing beach initially described by Chrzastowski and Thompson (1994) as Algonquin in age. His conclusion is based on radiocarbon, geomorphological, and sedimentological evidence. Lake Algonquin dropped episodically as lower outlets...

NOTE: All illustrations and photos have been removed from this article.



Looking for additional articles?
Search our database of over 3 million articles.

Looking for more in-depth information on this industry?
Search our complete database of Industry & Market reports by text, subject, publication name or publication date.

About Goliath
Whether you're looking for sales prospects, competitive information, company analysis or best practices in managing your organization, Goliath can help you meet your business needs.

Our extensive business information databases empower business professionals with both the breadth and depth of credible, authoritative information they need to support their business goals. Whether it be strategic planning, sales prospecting, company research or defining management best practices - Goliath is your leading source for accurate information.