No. 47: Sep-Oct 1986
"On two occasions it happened on a still night, suddenly -- a vibrant booming so loud I had to shout to be heard by my companion. Soon other sources, set going by the disturbance, joined their music to the first, with so close a note that a slow beat was clearly recognized. This weird chorus went on for more than five minutes continuously before silence returned and the ground ceased to tremble."
P.K. Haff opens his review of booming sands with the above quote from R.A. Bagnold. One would think that since booming sand is not uncommon and scientists can pick it up and take it back to their laboratories, we know all about why it booms so unexpectedly when set in motion down a dune face. Haff relates his own experiments and ties them into the rather large body of previous work on the subject. The factors of dampness, grain size, cleanliness, grain shape and smoothness, etc., have all been examined. But Haff concludes:
"In spite of these experiments and the work of other researchers, it is still not known how booming dunes work."
(Haff, P.K.; "Booming Dunes," American Scientist, 74:376, 1986.)
Reference. Booming dunes are cataloged along with "muscial sands" in ESP14 in the catalog volume: Anomalies in Geology. For ordering information, visit: here.