The area of Val d'Orcia is mostly made up of hilly terrains with gentle elevations and shallow valleys. Its landscape is characterized by the so-called "C rete ", as well as by a rich vegetation, especially along its external margins towards the valley bottom.
The course of the river Orcia cuts through the valley crossways and pours out of it through a deep cleft.
The beginning of the valley's geological history dates back to 5 million years ago, when the area started to rise due to the retreat of seawaters and the building up of sand and clay sediments, which created the surface layers of the valley.
Subsequently, the activity of the Radicofani and Amiata volcanoes spread a layer of lava over the pre-existing rocks. The lava cooled down and created igneous rock formations called trachytes.
The landscape has been shaped by erosion and, where the phenomenon is stronger, the clay substratum of a light color surfaces through the darker rocks. The most visible and peculiar forms of erosion have created unusual gullies called "Calanchi" and round bare clay formations called "Biancane", which are still visible in the areas of Casa a Tuoma (Pienza), Ripalta (San Quirico), Lucciolabella , Beccatello, Torre Tarugi (Pienza), and Contignano (Radicofani).
A wonderful gorge opens from Bagno Vignoni towards the north-west. It is made of living rocks and covered in forests and Mediterranean scrub stretching towards the sea and bordering the endless vineyards of the Montalcino area.
Moving towards the side of Mount Amiata, one enters a mountain forest mostly made up of beeches and chestnut trees. From a naturalistic point of view, the most interesting biotypes are those of Scarceta (where a truly beautiful holm oak forest is still intact) and of Abetina del Vivo (what is left of the original and very ancient Amiata forests); not far from these is the health resort of Vivo d'Orcia, a small old village famed for its spa, located just above the settlement.
The most common plant species in the area are the holm oak, the common oak, the Turkey oak, and the Quercus robur peduncolata, which make up thick forests that become denser moving into the land of Maremma; but the most characteristic tree of the Orcia Valley is undoubtedly the cypress.
The area is also very rich in animal species, there are hedgehogs, polecats, badgers, beech martens, weasels, foxes, long-eared owls, little owls, screech-owls, and tawny owls; it is not difficult to see buzzards, European serpent eagles, harriers, kestrels, Eurasian nuthatches, green woodpeckers, common ravens, wrynecks, and spotted flycatchers.