Mysterious singing sands discovered on Hainan coast
Chinese scientists have discovered an area of "singing sands" on the tropical island province of Hainan, the first time the strange auditory phenomenon has been identified on the country's coastline.
Singing sands – also known as rattling sands, whistling sands or musical sands – consist of sandy areas of desert or coastline that naturally produce sounds in the wind due to a combination of physical characteristics, including the size and composition of the grains.
According to the Northwest Institute of Eco-Environment and Resources (NIEER) under the Chinese Academy of Sciences, the discovery of singing sands on Hainan marks the first time that an area of Chinese coastline has displayed the phenomenon, and enhances the province's tourism potential.
"The discovery of the magical natural phenomenon fills the gap of coastal singing sands in China. It will provide technical support to the development and protection of tourism resources in Hainan," said Qu Jianjun, an NIEER researcher and leader of the team that made the discovery.
Singing sands can be found at multiple inland sites within China, including the renowned Singing-sand Mountain, located near the Mogao Grottoes in the oasis city of Dunhuang, in northwest China's Gansu Province. Such sites provide a draw to visitors, keen to experience the strange phenomenon.
"The distribution of coastal singing sands is regarded as a reflection of quality beaches. It has long been assumed that there are no coastal singing sands in China, and our latest study provides a new answer," said Qu.
The NIEER team discovered multiple singing-sand sites along the coasts of Clearwater Bay, Shenzhou Peninsula and other areas in Hainan.
The study shows that the unique geomorphology and wave-breaking dynamics of these bays have shaped the well-sorted coastal sands in terms of grain size.
The scientists investigated the characteristics of the coastal singing sands, such as the mineral composition, particle size, surface structure and acoustic characteristics, and compared them with those of singing sands in a desert region.
Their study shows that the surface of the coastal sands has typical V-shaped craters formed by underwater mechanical etching, and deep dissolution craters formed by chemical etching.
"This well-developed surface porous physical structure is an important factor in controlling the sound mechanism of the singing sands," said Qu.
However, the frequency spectrum of the coastal singing sands is narrower than that of the desert singing sands, with a high proportion of high-frequency components and a relatively sharp sound, according to the study.
Qu said the discovery of the coastal sands in Hainan reflects the resort island's excellent seawater and beach quality, which are significant characteristics for the tourism resources of Hainan Province, thus generating significant economic, social and ecological benefits.
"Further study regarding protection is needed," said Qu. "Meanwhile, it would be great to establish a coastal sand desert park, which could serve as a platform for scientific research and education."