White beaches and celestial mechanics. What do they have in common?
This picture-postcard scenery of Sicily exists thanks to the peculiar way in which our planet moves in space. It may sound incredible, and yet it’s what geologists found out by studying the white marlstone on the Agrigento coast.
How does the Earth move in space?
(a) it rotates around a titled axis;
(b) that shifts in orientation like a spinning top;
(c) and along an elliptical orbit that changes shape in time.
These three mechanisms work by cycles, called Milankovitch cycles, and have an impact on the amount of solar radiation that hits the surface of the Earth at a certain time.
If the solar radiation changes so does climate, and with it many other factors such as rainfall and temperature. In the long term, this cyclic pattern forms alternations of wet and dry periods.
What does it have to do with Southern Sicily’s wonderful beaches?
While the white marlstone was forming on the seafloor, successions of wet and dry periods were occurring due to Milankovitch cycles.
During wet periods, microfossils thrived on the seafloor giving the rock a white color.
During dry periods, desertification got more intense in North Africa; the winds blew towards Sicily and its seas spreading dust, which mixed with the microfossils giving the rock a beige color.
Besides color, this process influenced rock hardness as well, creating alternations of more and less indurated layers. And it is exactly this factor to create the majestic stairway-like aspect that characterises places like Scala dei Turchi.
As tree-rings correspond to annual cycles, in this rock every layer was deposited in the same amount of time.
Each layer of the marl was formed in about twenty thousand years.
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We walk to discover the stories hidden in the landscape. The true face of the land includes the border region in which it ends. For that reason we decided to cover a stretch along the coast.
“In the valley of the temples and astronomical cycles”: that’s how we call our journey chapter that starts from Agrigento.
