But it is difficult to test this prediction because large floods usually wipe out the record of earlier inundations. Jonathan Nott of James Cook University of North Queensland, Cairns, Queensland and David Price of the University of Wollongong, New South Wales describe a kind of waterfall which preserves information about older floods.
Most waterfalls are at the head of gorges that they have worn back into a cliff.
In these waterfalls, every flood fills the ravine to the brim so that it is scoured out. Only sand and pebbles carried down by the most recent large flood are left, and the record of older deluges is destroyed. Writing in the August issue of Earth and Planetary Science Letters , Nott and Price describe how waterfalls that are not at the head of gorges can preserve information about older floods. Venezuela's Angel falls are the world's highest Fast-flowing water can carry more sand, gravel and pebbles than slower moving water. In a shallow stream, fast moving stretches of the stream have rocky beds, and slower moving sections have sandy beds.