On the origin and significance of basal notches or footcaves in karst terrains
Date
2011
Authors
McDonald, R.
Twidale, C.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Journal article
Citation
Physical Geography, 2011; 32(3):195-216
Statement of Responsibility
Roy Charles McDonald, C. Rowland Twidale
Conference Name
Abstract
Albeit under various names (footcave, slot, cliff-foot cave, shelter, notch) basal indents form in various lithological and climatic environments. But footcaves in crystalline limestone are especially well and widely developed, not only in marine environments, but also inland. In the humid tropics, footcaves and swamp slots are associated with surface and shallow groundwaters charged with chemicals and biota. The indents developed around the bases of widely separated karst towers are responsible for their conversion from cupolas or domical residuals. Even in mature tower karst landscapes, some arcuate footcaves are shaped by laterally corrading streams in flood that have transported and deposited exotic debris. Such corrasion is, however, particularly widespread in youthful karst where valley floors are narrow. Here, footcaves not only may have been initiated, but also occasionally maintained, enhanced, and modified by migrating streams, as well as by scarp-foot weathering and sapping. Microorganisms that colonize moist walls of footcaves may also have contributed.