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GEOREF RECORD

Speleogenesis of the Mount Elgon elephant caves, Kenya

Joyce Lundberg and Donald A. McFarlane
Speleogenesis of the Mount Elgon elephant caves, Kenya (in Perspectives on karst geomorphology, hydrology, and geochemistry; a tribute volume to Derek C. Ford and William B. White, Russell S. Harmon (editor) and Carol M. Wicks (editor))
Special Paper - Geological Society of America (2006) 404: 51-63

Abstract

The eastern flanks of Mount Elgon, an early Miocene stratovolcano, host caves ( approximately 150 m long, approximately 60 m wide, approximately 10 m high) of debatable origin. Many animals, primarily elephants, "mine" the pyroclastic bedrock for sodium-rich salts. Speleogenesis has been argued to be primarily zoogeomorphic, or primarily dissolutional with only minor zoogeomorphic modification. This report provides the first detailed mapping and geomorphological study of the caves. Speleogenesis is polygenetic and strongly related to lithology. Geological units are, from the top down, approximately 2 m of dense pyroclastic agglomerate cap rock over which water falls, approximately 10 m of more permeable agglomerate, up to approximately 0.2 m of discontinuous impermeable lava, approximately 2 m of very soft and permeable agglomerate, and >2 m of impermeable swelling-clay tuff. Caves develop behind waterfalls under surface stream valleys by sapping of the incompetent agglomerate above the clay, and failure of the clay (aquiclude and base level for speleogenesis), followed by collapse of harder agglomerate layers above. The dominant passage shape is breakdown dome, with abundant fresh collapse. Geophagy by elephants and other species, and human mining significantly modify and enlarge the caves and remove collapse debris. These activities, focused on accessible and salt-rich units, create quasi-horizontal undercuts (up to approximately 4 m tall and deep), the loci of which move upward as collapse raises the floor. Significant erosion also occurs by incongruent dissolution, corrosion, pressure release, efflorescence flaking, and biogeochemical activity from huge bat colonies. No evidence was found of channeled flow, or of phreatic or vadose activity. These caves are probably no older than Holocene.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 404
Title: Speleogenesis of the Mount Elgon elephant caves, Kenya
Title: Perspectives on karst geomorphology, hydrology, and geochemistry; a tribute volume to Derek C. Ford and William B. White
Author(s): Lundberg, JoyceMcFarlane, Donald A.
Author(s): Harmon, Russell S.editor
Author(s): Wicks, Carol M.editor
Affiliation: Carleton University, Department of Geography and Environmental Studies, Ottawa, ON, Canada
Affiliation: U. S. Army Research Office, Environmental Sciences Division, Research Triangle Park, NC, United States
Pages: 51-63
Published: 2006
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 978-0-8137-2404-1
ISBN: 0-8137-2404-7
References: 20
Accession Number: 2006-075406
Categories: Geomorphology
Document Type: Serial Map
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., strat. col., sketch maps
Map Scale: 1:1000
Map Type: cave map
N00°10'00" - N00°19'60", E34°30'00" - E35°30'00"
Secondary Affiliation: University of Missouri-Columbia, USA, United StatesW. M. Keck Science Center, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200643
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