Importance of the Regelation Process to Certain Properties of Basal Tills Deposited by the Laurentide Ice Sheet in Iowa and Illinois, U.S.A

Kemmis, Timothy J.

doi:10.3189/172756481794352351

Cited by 30 publications

(25 citation statements)

References 10 publications

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“…Relatively sharp basal-till contacts and undeformed, weak sub-till beds are more likely with a deforming-bed origin for tills than with a rigid-bed origin, contrary to the proposals of Kemmis (1981Kemmis ( , 1986, Sharpe (1986), and others (1987, 1989). This is based on several lines of evidence: 70 the high basal velocities and low shear stresses of the ice lobes that deposited these till sheets seem to require a melted, saturated bed with high water pressure.…”

Section: Tills Exhibit Sharp Basal Contacts With Undeforlded or Weaklcontrasting

confidence: 47%

“…As summarized by Kemmis ( 1981Kemmis ( , 1986, Beget (1986), Sharpe (1986), and others (1987, 1989), among others, these basal tills:…”

Section: Till Observationsmentioning

confidence: 99%

“…Stratigraphically (Kemmis, 1981;Wickham and J ohnson, 1981;Wickham and others, 1988;Clayton and others, 1989…”

Section: Till Observationsmentioning

confidence: 99%

“…Possible transport mechanisms include a regelation layer (Kemmis, 1981), a thicker layer of debris-rich basal ice, and a deforming bed.…”

Section: Model-data Relations: Sediment Fluxesmentioning

confidence: 99%

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Deforming-bed origin for southern Laurentide till sheets?

Alley

1991

J. Glaciol.

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ABSTRACT. The widespread, uniform till sheets of the southern margin of the Laurentide ice sheet were deposited by fast-moving, wet-bedded ice over relatively short periods of time. Characteristics of these till sheets are entirely consistent with deposition from deforming subglacial sediment layers; it is difficult (although not impossible) to explain their origin through debris transport in basal ice. Careful estimation of debris budgets and studies of sorted sediments contained in the till sheets may clarify their origin further.

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Section: Tills Exhibit Sharp Basal Contacts With Undeforlded or Weaklcontrasting

confidence: 47%

“…As summarized by Kemmis ( 1981Kemmis ( , 1986, Beget (1986), Sharpe (1986), and others (1987, 1989), among others, these basal tills:…”

Section: Till Observationsmentioning

confidence: 99%

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Deforming-bed origin for southern Laurentide till sheets?

Alley

1991

J. Glaciol.

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“…Multiple criteria yield the best results, however, the most common techniques frequently used for correlation have been matrix texture and lithologie composition of various till sheets; these can be identified by careful field mapping primarily and by laboratory analysis. The fact that till sheets often show uniform matrix composition (texture) is a properly that is widely used and it allows for glaciological interpretations (KEMMIS, 1981). Matrix texture may remain very uniform over large areas (100-400 km 2 ) and this allowed strata such as subglacial Catfish Creek till faciès to be traced from river bank to river bank (Fig.…”

Section: Present Statusmentioning

confidence: 99%

Significance of Sedimentological Studies on the Wisconsinan Stratigraphy of Southern Ontario

Sharpe¹,

Barnett²

2007

gpq

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ABSTRACTDetailed facies mapping along Lake Erie and Lake Ontario Bluffs, plus other studies illustrate that sedimentological studies, especially those with geomorphic or landform control, have had three main effects on the Wisconsinan stratigraphy of Ontario: (1) improved understanding of depositional processes and environments of several major rock stratigraphic units, without altering the stratigraphic framework, (2) aided correlation of drift sequences, and (3) questioned previous interpretations and stratigraphic correlations of drift sequences. Thus sedimentological analysis can not be separated from stratigraphy because the interpretation of depositional environnments of many mapped strata relies on their geometry and the inclusion of regional data. The geomorphic control provided by sedimentological study of surface landforms is also important because assessment of older buried sediments such as those at the Scarborough Bluffs has been hampered by the failure to determine landform control. The Late Wisconsinan stratigraphy of Southern Ontario generally remains unchanged, except for questions on the role of climate versus ice margin dynamics. The pre-Late Wisconsinan stratigraphy is scarce and not well defined, yet sedimentary studies support the presence of glacial ice in the Ontario Lake basin for all of the Middle Wisconsinan and possibly earlier, including the formation of the Scarborough delta. Large channel cut and fill sequences in the Toronto area (Pottery Road Formation), initially interpreted as resulting from subaerial erosion, were probably formed by subaqueous or subglacial meltwater erosion. If so, the pre-Late Wisconsinan stratigraphy in southern Ontario changes because the Pottery Road Formation may not be an Early Wisconsinan correlative of the St. Pierre beds. The channel example illustrates that stratigraphie correlation without sedimentological investigations may be misleading.

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References

2017

Till: A Glacial Process Sedimentology

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Importance of the Regelation Process to Certain Properties of Basal Tills Deposited by the Laurentide Ice Sheet in Iowa and Illinois, U.S.A

Cited by 30 publications

References 10 publications

Deforming-bed origin for southern Laurentide till sheets?

Deforming-bed origin for southern Laurentide till sheets?

Significance of Sedimentological Studies on the Wisconsinan Stratigraphy of Southern Ontario

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