[1] The sand formations were created when sediment deposits carried from the Chūgoku Mountains by the Sendai River were thrown away into the Sea of Japan.
Strong winds then shaped the dunes over a span of 100,000 years.
[2] The area of the dunes has been steadily decreasing due to a government reforestation program following World War II.
Concrete barriers have been built along the coast to prevent the formations from eroding.
Authorities have adopted measures to stop the shrinkage of the dunes, partly because they attract a significant amount of tourism to the area.