Mahomet Bedrock Valley in east-central Illinois; Topography, glacial drift stratigraphy, and hydrogeology

Kempton, John P.; Johnson, W. Hilton; Heigold, Paul C.; Cartwright, Keros

doi:10.1130/spe258-p91

Cited by 31 publications

(35 citation statements)

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“…The Pleistocene glacial aquifer system was deposited in an ancient river valley by continental glaciations during the past several hundred thousand years (Kempton et al, 1991). The water-bearing sediments are largely unconsolidated sands and gravels, whereas the confining layers are composed of glacial till.…”

Section: Introductionmentioning

confidence: 99%

Bacterial sulfate reduction limits natural arsenic contamination in groundwater

Kirk¹,

Holm²,

Park³

et al. 2004

Geol

226

117

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Natural arsenic contamination of groundwater, increasingly recognized as a threat to human health worldwide, is characterized by arsenic concentrations that vary sharply over short distances. Variation in arsenic levels in the Mahomet aquifer system, a regional glacial aquifer in central Illinois, appears to arise from variable rates of bacterial sulfate reduction in the subsurface, not differences in arsenic supply. Where sulfate-reducing bacteria are active, the sulfide produced reacts to precipitate arsenic, or coprecipitate it with iron, leaving little in solution. In the absence of sulfate reduction, methanogenesis is the dominant type of microbial metabolism, and arsenic accumulates to high levels.

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Section: Introductionmentioning

confidence: 99%

Bacterial sulfate reduction limits natural arsenic contamination in groundwater

Kirk¹,

Holm²,

Park³

et al. 2004

Geol

226

117

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“…At some localities, the sand and gravel deposits at the base of the Vandalia are hydraulically connected with the Mahomet aquifer because the Hillery and Tilton Members are absent and the top of the Mahomet aquifer is relatively high. The Wedron Group (Figure 4), which was deposited during the Wisconsin Glacial Episode between 25,000 and 12,000 years ago (Soller et al, 1999), contains thin beds of Kempton et al, 1991 andBurch andKelly, 1993). …”

Section: Hydrogeologic Setting Of the Mahomet Aquifer In East-centralmentioning

confidence: 97%

The Mahomet Aquifer

Larson

Mehnert

Herzog

2003

Water International

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Emerging intrastate transboundary issues focus on use of the Mahomet aquifer, which underlies about fifteen counties and many other political entities in east-central Illinois. This sand and gravel aquifer in the lower part of the buried Mahomet Bedrock Valley ranges between four and fourteen miles wide and from about 50 to 200 feet thick. Much of the region's rural population, several large communities, and many small towns obtain water from the Mahomet aquifer, as do industrial, agricultural, and commercial users. Increased development of the Mahomet aquifer to meet growing demands for water has caused conflicts over real or perceived adverse effects. One result has been the creation of fifteen resource protection zones and twelve water authorities. For groundwater supplies, resource protection zones help municipalities protect water-supply wells from potential adverse impacts. Many resource protection zones overlap one another, however, so this situation could lead to disputes over use of the resource. The reason that several of the twelve water authorities were organized was to meet a challenge perceived from a demand to be placed on the aquifer, in other words, a potential for conflict of use. Complicating the situation is that some of the water authorities overlap the resource protection zones. This could lead to disputes not only about water use, but also over which jurisdiction has the authority to settle a dispute. The Mahomet Aquifer Consortium was recently organized by concerned people representing diverse groundwater interests at the local level, including the private sector, professional organizations, and various governmental units. The consortium brings together representatives of some groups that typically did not communicate with each other in the past. The consortium may provide a forum through which emerging transboundary issues pertaining to use of the Mahomet aquifer can be addressed. Because the consortium is a voluntary organization that relies on consensus building, the success it may achieve in resolving future conflicts over groundwater use from the Mahomet aquifer remains to be seen.

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“…During the pre-Illinois Episode in the USRB (∼1.2-0.4 Ma), glaciofluvial sediment (or outwash) was repeatedly deposited and excavated from the MBV. Such outwash mainly filled the preglacial bedrock valley and is overlain by till sequences with some glaciolacustrine sediment ( Figure 5C; Kempton et al, 1991;Stumpf and Atkinson, 2015). (moraines) is dominant.…”

Section: Upper Sangamon River Basin Illinoismentioning

confidence: 99%

“…Three or more pre-Illinois Episode till sequences, together up to 30 m thick, occur in areas outside the MBV or overlie the pre-Illinois Episode glaciofluvial deposits (Kempton et al, 1991;Stumpf and Atkinson, 2015). Following the pre-Illinois Episode glaciations, a long period of weathering, soil formation and landscape denudation occurred during the Yarmouth interglacial episode (∼0.4-0.2 Ma) (Grimley et al, 2003;.…”

Section: Upper Sangamon River Basin Illinoismentioning

confidence: 99%

Critical Zone Structure in the Glaciated Interior Lowlands, Usa: A Conceptual Model From the Intensively Managed Landscape Critical Zone Observatory

Anders¹,

Bettis

Grimley

et al. 2018

Geological Society of America Abstracts With Programs

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The concept of a critical zone (CZ) supporting terrestrial life has fostered groundbreaking interdisciplinary science addressing complex interactions among water, soil, rock, air, and life near Earth's surface. Pioneering work has focused on the CZ in areas with residual soils and steady-state or erosional topography. CZ evolution in these areas is conceptualized as progressive weathering of local bedrock (e.g., in the flow-through reactor model). However, this model is not applicable to areas in which weathering profiles form in transported materials including the formerly glaciated portion of the Central Lowland of North America. We present a new conceptual model of CZ evolution in landscapes impacted by continental glaciation based on investigations at three study sites in the Intensively Managed Landscapes Critical Zone Observatory (IML-CZO) The IML-CZO is devoted to the study of CZ processes in a region characterized by thick surficial deposits resulting from multiple continental glaciations, with bedrock at depths of up to 150 m. Here the physical (glacial ice, loess, developing soil profiles) and biological (microbes, tundra, forest, prairie) components of the CZ vary significantly in time. Moreover, the spatial relationships between mineral components of the CZ record a history of glacial-interglacial cycles and landscape evolution. We present cross-sections from IML-CZO sites to provide specific examples of how environmental change is recorded by the structure of the mineral components of the CZ. We build on these examples to create an idealized model of CZ evolution through a glacial cycle that represents the IML-CZO sites and other areas of low relief that have experienced continental glaciation. In addition, we identify two main characteristics of CZ structure which should be included in a conceptual model of CZ development in the IML-CZO and similar settings: (1) mineral components have diverse origins and transport trajectories Anders et al. CZ Structure at IML-CZO including alteration in past CZs, and, (2) variability in climate, ecosystems, and hydrology during glacial-interglacial cycles profoundly influence the CZ composition, creating a legacy retained in its structure. This legacy is important because the current physical CZ structure influences the occurrence and rates of CZ processes, as well as future CZ responses to land use and climate change.

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Mahomet Bedrock Valley in east-central Illinois; Topography, glacial drift stratigraphy, and hydrogeology

Cited by 31 publications

References 0 publications

Bacterial sulfate reduction limits natural arsenic contamination in groundwater

Bacterial sulfate reduction limits natural arsenic contamination in groundwater

The Mahomet Aquifer

Critical Zone Structure in the Glaciated Interior Lowlands, Usa: A Conceptual Model From the Intensively Managed Landscape Critical Zone Observatory

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