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One of the common assertions in the literature is that booming dunes are rare. The standard test of whether a dune booms or not is to climb up to the top of a nearby slipface and forcefully dislodge sand with a boot. The Kelso Dunes in the Mojave Desert of California feature well-known booming sands, and the boot test often gives spectacular and memorable results (10). But not always. Booming dunes are temperamental, sometimes booming, sometimes mute. Some days will find the Kelso sands uncooperatively silent. Moreover, some slipfaces on a nominally booming dune such as at Kelso can never be made to boom.
A laboratory test for booming would clearly be of great value. Lewis showed that this was possible (7). He noted that bags of sand brought back to Pretoria would "roar" when disturbed. In this spirit, we collected one gallon plastic milk jugs of sand from a number of desert dune sites and took them back to the laboratory. On the dunes that boomed when booted, it was discovered that the loudest sounds are invariably produced near the dune crests and that basal regions of the dune bark only weakly if at all. On the basis of this observation, samples were collected from these two regions.
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发表于 2019-10-14 21:07:48
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