The Gavarres massif is the northeastern end of the Litoral range. It has gentle terrain and is surrounded by normal (relatively modern) Neogene faults that have led to tectonic pits such as La Selva in the south; or that of the Empordà, in the north, and the current coast in the east.

The outlying rocks are very ancient, over 450 million years, from the Paleozoic age. The main ones are: sandstone, lutite and limestone, the latter used in old lime kilns present in the area. We also find rocks of volcanic origin of the same age. All these rocks have a low degree of metamorphism.

The ease of alteration of these rocks often causes them to be covered by soils that facilitate the implantation of the large forest mass that covers the area, leaving a landscape in which the vegetal mantle of holm oak and cork forests stands out above all.