Imaggeo On Monday: Stands of Time

Imaggeo On Monday: Stands of Time

Within the heart of the Malagasy Hauts-Plateaux, the rolling grasslands are pitted by deep incisions locally referred to as lavaka (‘hole’ in Malagasy). These mass failure features provide vast quantities of terrestrial matter to local freshwater arteries, accounting for over 80% of the annual sediment load of the Betsiboka River. The collapse of the overlying laterite exposes a comparatively nutrient enriched saprolite layer, and in later stages of lavaka evolution, these conditions provide the substrate for a relatively species-rich microcosm isolated amongst the homogenous grasslands, as can be seen here.

The imagery evoked from this lavaka is unmistakeable; the cascading vegetation draining through the neck of the hourglass as time progresses, mirroring the cycles of erosion and stabilisation so characteristic of these dynamic landscape features.

Description by Trent Marwick, after the description on


Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at

This guest post was contributed by a scientist, student or a professional in the Earth, planetary or space sciences. The EGU blogs welcome guest contributions, so if you've got a great idea for a post or fancy trying your hand at science communication, please contact the blog editor or the EGU Communications Officer to pitch your idea.

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