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Sound-Producing Dune and Beach Sands

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Sound-Producing Dune and Beach Sands Sound-producing dune and beach sands JOHN F. LINDSAY Marine Science Institute, University of Texas at Galveston, Galveston, Texas 77550 DAVID R. CRISWELL Lunar Science Institute, 3303 Nasa Road 1, Houston, Texas 77058 T. L. CRISWELL Battelle Pacific, Northwest Laboratories, Richland, Washington 99352 B. S. CRISWELL Department of Microbiology, Baylor University College of Medicine, Houston, Texas 77001 ABSTRACT discernible once prolonged avalanching is established, hence the term "booming sand." Humphries (1966, p. 139) described the Field and laboratory investigations have confirmed differences low frequency as beating at about 1 Hz. Dryness is essential for between the acoustic and seismic emissions of "singing" and sound production. Warm or hot sand generally seems to boom best "booming" sands and revealed that booming grains possess ex- but heat is not essential. Avalanches can be many metres on a side tremely smooth surfaces. Singing sand is the most common of the (and as much as a few centimetres deep) in the natural case or only two types of sound-producing sands. It occurs widely as a beach a few cubic centimetres when the sound is evoked by pulling one's sand and consists of well-rounded highly spherical grains that have fingers through the sand. Avalanche velocities range from 20 to 30 a well-sorted highly symmetric grain-size distribution. Sound is cm sec-1 in both silent and booming events. The sound-producing produced when the sand is mechanically sheared, possibly causing sands are commonly termed "desert thunder," "booming dunes," the closely packed grain array to dilate in a coherent manner. Fre- and "roaring sands." There have been no reports in which one type quency (>500 Hz) is controlled by grain size, and amplitude may of sand (squeaking or booming) could be manipulated to evoke in part relate to grain morphology. Booming sand is a relatively both the high- and low-frequency emissions. rare phenomenon that occurs in some desert regions. This sand The properties of these two types of sands are not well known produces a low-frequency (f„ = 80 Hz) sound during avalanching. despite the widespread although rare occurrence. In this paper the The process efficiently (=0.1 to 1 percent) produces very narrow morphological properties of sound-producing sands are studied in band seismic energy in the 50- to 80-Hz range. Simultaneously an attempt to understand their unique characteristics. Criswell and produced audio signals are broader band but are composed of others (1974, 1975) described in detail the first quantitative mea- signals that peak at the same fundamental frequencies as the seis- surements of seismic and acoustic emissions of a booming dune. mic emissions. In addition, the acoustic emissions display first and Application of the booming phenomenon to lunar seismic data and second harmonics. Acoustic production is ~ 400 times less efficient thermal quakes on the Moon was discussed by Criswell and Lind- than seismic energy production. Booming occurs in quartz and say (1973, 1974). carbonate sand grains that are well sorted, fine skewed, and mesokurtic. The individual quartz sand grains are only moderately BOOMING SAND well rounded. When compared to normal eolian grains, however, they have highly polished surfaces that are smooth on the 1-/Ltm Booming dunes have been mentioned in mideast literature for at scale. The exceptional smoothness of the grains may facilitate least 1,500 yr and in Chinese literature from as early as the ninth booming. The effective Q (magnification factor) and compressibil- century (Stein, 1912). Booming sand has since been reported from ity (k) of the grain system may be the key physical quantities in- the Middle East, the Sahara Desert, southern Africa, Chile, Baja volved in booming. Thus, whereas booming is rare in the terrestrial California, California, Hawaii, and Nevada (Fig. 1, Table 1). environment, it may be common in the high-Q soils of the Moon Instrumental measurements of the acoustic and seismic output of and the near waterless dune environment of Mars. Key words: booming sand have never been reported. This is clearly of impor- sedimentary petrology, extraterrestrial geology, dune sand, beach tance not only to obtain quantitative information on the relative sand, eolian, seismology, acoustic, deserts, geophysics. spectral output of the dunes but on the efficiency of conversion of the slumping energy of the grains into seismic and audio output. INTRODUCTION Of several known booming dunes in the U.S., two were visited and sampled, and acoustic and seismic signals were recorded at one Two types of sands emit loud and distinct — often music-like — locality. sounds when they are sheared. Most common is a particular type of beach sand that emits a short note in the 500- to 2,500-Hz range of a few tenths of a second or less duration when sharply poked or stepped on (Brown and others, 1964; Takahara, 1973). Colloqui- ally, these are called singing, squeaking, barking, or whistling sands. Sound production by desert dune sand is less common and has been likened to that produced by a kettle drum, zither, nakus, bass violin (Curzon, 1923), or low-flying propeller aircraft (Humphries, 1966). All describe a loud, relatively low-frequency sound being produced by loosely flowing or avalanching sand. Lewis (1936) estimated the frequency of the sound between 132 and 300 Hz, whereas Humphries (1966) placed the frequency at between 50 and 100 Hz. Also common to many descriptions of the sound produced by the desert dune sand is that a much lower beat frequency is Figure 1. Map showing the location of booming sand. Geological Society of America Bulletin, v. 87, p. 463-473, 12 figs., March 1976, Doc. no. 60316. 463 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/87/3/463/3433909/i0016-7606-87-3-463.pdf by guest on 25 September 2021 464 LINDSAY AND OTHERS TABLE 1. LOCATION OF BOOMING SAND DUNES Name and location Type and size Comments and references (lat, long) (height x width X length) Hill of Sounding Sand Dune field Like rumble of distant carts, drums, or thunder; audible 5.4 to 10 km; near Tunyang, China 100 m X 20 km X 40 km small lake at "Caves of Thousand Buddhas"; possibly at toe of dune field 40°03'N, 95°00'E) (1, 2, 3, 17) Reg-i-Ruwan Sand drift On detached foothill of Paghman Range; sand supply not obvious; booms 64 km north of Kabul, Afganistan 130 m X 130 m spontaneously about 12 times a year; loud hollow drum sound (approx. 35°N, 69°E) (1) Rig-i-Riwan Sand drift On detached ridge of Calakoh Range; on southern face; no sand on adjacent Between Herat, Afganistan, and 200 m x 800 m hills, surrounding terrain not sandy; audible at 16 km; like vibration of Sijistan due north of district of telegraph wires of Kalah-i-Kah (1) Jebel Nakus Sand drift Faces Gulf of Suez 3 km to the east; in situ humming sound; from a distance, 11 km north of Tor, Sinai like distant cannon or deep bass of pipe organ; ground vibration and sand (28°18'N, 33°33'E) detachment during flow (1,5) Bedawin Ramadan Sand drift Audible at 30 m; bass note Wadi Werkan, Sinai, north of Jebel, 13 m x ? x ? (1,5) Nakus Oh Shomar Sand drift Bass note Mountain of the Sinai group (1) Rowsa No details Several nameless dunes identified by nearest oasis, Nefuz desert near El-Hyza, Deffafiat Arabia Subbia (1) Itzum Wadi Hamade No details Northern Arabia, north of Medina (1) Nameless Probably barchan In Uruq Adh Dhahiya region of the "empty quarter" of Arabia; like foghorn, Sand of Yadila 30 m x ? x ? 2-min duration (22) Nameless No details Near dead city of Jahura Arabia (1) (approx. 22°N, 51°E) Jebel-et-Tabul No details Between Medina and Mecca Arabia (1) Nameless No details Near Taif in sand belt of Arq-al-Subai; many booming dunes Abraq-al-Manazil, Arabia (1, 19) Nameless No details 150 km ESE of Medina Khanug, Arabia (1) Nameless Sand sheets On or close to Nubian sandstone plateau; sand coated with iron oxide; Gilf Kebib Desert Seifs many booming sands in area (23°N, 26°E) Barchans (2, 4) Es-Sadat Sand drift In cave on hillside in western Beirut facing "Pigeon Rock"; sound resembles Beirut, Lebanon beating of tambourines (1) Sand Mountain, Nevada crophone. A complete report on the acoustic and seismic observa- tions, instrumentation details, and analysis procedures was given in Sand Mountain (Fig. 2) is a booming sand dune that lies 5 km Criswell and others (1975). At the time of the visit, the dune sand north of U.S. Highway 50 about 25 km southeast of Fallon, was extremely dry. Sand at most places on the dune, but especially Nevada. The dune lies on the northeastern end of a large salt pan on the ridge line, could be made to produce a sound by setting in and in the constriction of a rocky pass. The prevailing wind direc- motion a mass of sand more than 10 to 15 cm in thickness. On the tion is to the northeast across a salt pan; the wind is then deflected gentler slopes at the base of the dune, slumping had to be induced down the narrow rocky pass in which the dune has formed. The artificially; however, higher on the dune where the slope exceeded dune location appears to be static, and little change has occurred in 52 percent (27°), sound-producing avalanches were readily ini- dune morphology in the last 10 yr (C. Snyder, 1973, personal tiated. Aural observations during the traverse were comparable commun.).
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