2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 4
Presentation Time: 2:30 PM


GRESS, Elizabeth A.1, COX, Rónadh1 and RAKOTONDRAZAFY, A.F. Michel2, (1)Department of Geosciences, Williams College, Williamstown, MA 01267, (2)Département des Sciences de la Terre, Université d'Antananarivo, BP 906, Antananarivo, 101, Madagascar, Elizabeth.Gress@williams.edu

Lavakas are large gullies that form in the thick laterite and saprolite of Madagascar's deeply-weathered crystalline basement. Although little known outside of Madagascar, they are a common geologic hazard in this developing nation, causing the collapse of roads and the inundation of rice fields with debris flows. Conventional wisdom states that lavakas are directly related to human activities and to land mismanagement, but in fact these claims are not based on scientific data collection. The origins of lavakas and the rates at which they grow and evolve are not yet understood, but research suggests that lavakas are a natural element of Madagascar's Holocene landscape.

The Malagasy highlands are characterized by steep slopes, developed in saprolite up to 100 m thick; so the landscape is inherently unstable and prone to rapid erosion. While it is definitely true that some lavakas form due to human activities, the non-scientific alarmist portrayal of lavakas as wholly anthropogenic is unfounded, and damaging to both to national morale and international perception of the Malagasy people. By careful data collection and careful reporting we hope to dispel some myths and increase general understanding of the fundamental causes of lavaka formation.

Part of our goal is to make our findings widely available. We plan to provide practical guidance to infrastructure planners in Madagascar, by meeting local leaders and presenting our technical results in oral and report form. We also hope to provide the general public with a balanced picture of this complicated phenomenon, by constructing well-illustrated summaries of our results for submission to a variety of wide-readership and popular-science publications in English and in Malagasy. Wide dissemination of accurate information, based on scientific principles and high-quality data analysis, but framed clearly and interestingly, is especially important as Madagascar gains increasing international attention due to its prominence as a biodiversity hotspot. The challenge lies in presenting a nuanced understanding of a complicated phenomenon in which the roles of man and nature are intimately entangled.