He follows you throughout your holiday at the sea, becomes your best friend when he stays wisely under your towel, and quite the opposite when he comes to invade the inside of your swimsuit. It is also a great success with the youngest, who works for whole afternoons to model it to create castles and other ball tracks.
So you have probably already asked yourself this question, during a long and pleasant day of idleness: where does the sand that we tread on most of the beaches of the world come from?
Where does the sand come from?
It turns out that the answer is not necessarily the same depending on where you are. “The sands come from different sources. They do not have the same appearance, the same dimensions”, warns Carlos Oliveras, a coastal specialist at the Bureau of Geological and Mining Research (BRGM), to 20 Minutes.
Indeed, on some beaches, the sand may seem a little coarser, while others display a bed of grains so smooth that one would almost think oneself in Paradise. This difference is mainly due to the level of degradation of the rock that composes it, under the effect of water, temperature, and wind.
“The color of the sand also depends on the minerals that compose it (quartz, mica, feldspar…). We can find black sands overseas, in volcanic areas, such as Martinique, Guadeloupe or Reunion”, completes the specialist.
For example, Brittany has sand from the erosion of granite coasts, while that of Normandy is more calcareous. And the white sand of the atolls that makes us dream so much is of organic origin, composed of fragments of corals, shells, and skeletons of organisms.
Sand, a (very) useful material
Most of the time, the formation of sandy beaches is not new. “The sand on the current beaches was set up 3,000-4,000 years ago,” explains David Menier, a marine geologist at the Laboratoire géosciences océan (LGO) at the Université Bretagne Sud, in Ouest France.
And beyond the aesthetic aspect of comfort, it brings to our little feet and is a natural barrier that protects against swells or sea storms. But it is also (unfortunately) very useful in the industry, especially the construction industry.
Many groups and companies come to “draw” in this nature reserve far too frequently for the sand reserve to be able to reconstitute itself, which has the consequence of pushing back very many beaches and even to make disappear. So much so that many experts fear that the sand will eventually disappear due to human activity.