As a meeting point, in the border between the march and the stabilised sands or reserves, there is a strip of land that gets wider from south to north, due to the water filtrations of the dunes and the most permeable As a meeting point, in the border between the march and the stabilised sands or reserves, there is a strip of land that gets wider from south to north, due to the water filtrations of the dunes and the most permeable sands.

As it hits the impermeable and clayey soil of the marsh, it emerges and maintains the humidity constant allowing the growth of wide pasturelands where a great amount of species of both ecosystems converge, converting this ecotone into a favourite place for great mammals: deer, fallow deer, cows, wild boars and marsh mares.