Under the Muraglie, the Casana Valley expands considerably in a space of 14 hectares, then narrows suddenly into a gorge: as a whole, the combination of these morphologies and the flat bottom have created what appears to be a large decantation bowl in which the largest alluvial materials have accumulated for centuries.

In the subsequent area, so-called Melette Plain, fine sand and soil have deposited. The residents of Caso have been able to take advantage of this happy geo-morphological combination for centuries and used the 12-13 hectares of the Melette Plain to successfully cultivate farm produce, especially hay and fodder. The Plain, at its best during Spring, dotted by apple trees, almond trees and willows, also provides food for the wild animals.

Crops and vineyards have also been planted on the right slope of the Plain where a centuries-old hazelnut and fig tree tower above a nearby medieval fountain.