Journal of Cave and Karst Studies - ISSN 1090-6924
Volume 66 Number 3: 89-97 - December 2004

A publication of the National Speleological Society

Some carbonate erosion rates of southeast Alaska
Kevin Allred

Abstract

As a way to determine the erosion rate of carbonate bedrock surfaces in Southeastern Alaska, an instrument was designed to directly measure the lowering of rock surfaces relative to fixed stainless steel bolts epoxied into the rock. A total of 582 measuring points were set in 31 measurement sites. Dissolution was found to be the predominant mode of erosion at most stations. Dissolution rate increased with thicker humus soil, but the presence of silty soil limited dissolution, even with deep humus. After deforestation of karst landscapes there was a preliminary dissolution rate increase from 38 mm/ka to 46 mm/ka. Bare rock erosion rates ranged from 31 mm/ka under old growth forests, to 38 mm/ka in alpine settings. Both bare and soil covered site results were similar to measurements elsewhere in the world where precipitation is comparable. However, Alaskan runoff from acidic peat bogs produced dissolution rates up to 1.66 m/ka, which are some of the highest known anywhere.

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