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Possible hydraulic significance of two kinds of potholes; examples from the paleo-Potomac River

E-an Zen and Karen L. Prestegaard
Possible hydraulic significance of two kinds of potholes; examples from the paleo-Potomac River
Geology (Boulder) (January 1994) 22 (1): 47-50

Abstract

Potholes preserved along abandoned sections of bedrock-bounded rivers should provide significant paleohydraulic data if the conditions for pothole formation are understood. In a prototype study, we recognize two kinds of potholes along the paleo - Potomac River near Great Falls, Virginia. Vertical potholes, drilled into the strath floor, are circular in plan and are interpreted to form at sites of small stream depths and high flow velocity. Lateral potholes, noncircular with overhanging roofs, are found on flanks of rock obstacles. They are interpreted to be eroded by sediment-laden vortical flow near the air-water interface. The vortices circulate water in the horizontal plane, and begin to form near the free surface in flow separation zones downstream of the obstacles. The geometry of flow separation zones and thus the location of the lateral potholes are scaled by flow Reynolds number. Therefore, lateral potholes could be used to reconstruct paleoflow depths and velocities if parts of the channel bed adjacent to the flow obstruction are preserved.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 22
Serial Issue: 1
Title: Possible hydraulic significance of two kinds of potholes; examples from the paleo-Potomac River
Affiliation: University of Maryland, Department of Geology, College Park, MD, United States
Pages: 47-50
Published: 199401
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 17
Accession Number: 1994-015560
Categories: Geomorphology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
S44°00'00" - S10°00'00", E113°00'00" - E154°00'00"
N36°34'60" - N39°28'00", W83°34'60" - W75°15'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 199407
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