Tag: Elsa River

Elsa Fiume (Elsa River)

One of our favorite walks is along the Elsa River (about 4 miles round trip). The headwaters of the Elsa are near Siena. From there, it flows north through Colle di Val d’Elsa to the Arno (the river that runs east-west through Florence). The turquoise color of the river is due to the limestone river bed. The river erodes the limestone releasing microscopic crystals of calcium carbonate. These crystals reflect blue and green light creating the unusual color. Actually, satellite images of the ocean can have turquoise patches if there is a bloom of coccolithophorids, which have calcium carbonate in their cell walls…that’s probably enough of that.

The Elsa is the green strip running up through the middle of the image.
The light green “cones” are from a wild hops plant. It’s a vine growing through something else. The three-lobbed leaves on the left are the hops leaves.
The Elsa has cut a bit of a canyon so the river is well below the level of the town. In the Middle Ages, they went upstream and dug a canal to bring water in at the level of the city. This is the gatehouse to regulate flow into the canal.