Relief. The structure of the Pyrenees in the Basque area offers an intricate folding and a considerable depression. The peaks drop in altitude from Iror Errege Maya to Aralar, in the centre of the country, and begin to rise again to the Ordunte mountains. The watershed or Pyrenean chain itself:

1. (Iror Errege Maya (2,434 m), Ori (2,029 m), Aralar (1,427 m), Aizgorri (1,544 m), Anboto (1,544 m), Aizgorri (1,544 m) and the Pyrenees (1,544 m), and the Pyrenees (1,544 m). ), Anboto (1.296), Gorbea (1.475), Orduña (1.039), Ordunte (Burgeño, 1.037).

2. Another line of mountains parallel to the previous one, or Pre-Pyrenees (Leire, Perdón. Sarvil, Andia, Montes de Vitoria, Oteroa, Arkamo, Guibijo).

3. A third succession of mountain ranges of lower altitude, almost parallel to the previous ones, pierced by the Ebro at Haro in the section known as Montes Obarenes (Alaiz, Eskinza, Cantabria, Obarenes), from all of which mountainous foothills rise up, to the north or south in such abundance that they give the country a labyrinthine and intricate appearance.

In the Cantabrian area, the foothills that start in the Pyrenees form rugged valleys that flow into the great rivers: Saison, Errobia, Ugarana, Bidasoa, Oyarzun, Urumea, Oria, Ibalzabal, etc. In the Zuberoa, Benabarre and Laburdi area, there is a series of massifs, or Pre-Pyrenees, crossed by the Pyrenean rivers: the Oskitz, Hotxamendi, Pagaburu, Yparlatza, Baigura and Urzuia mountains. In the centre of Guipúzcoa, the mountains that run from the Navarre border to Vizcaya: Unamuno, Urdelar, Adarra, Uzturre, Ernio, Elosumendi, Irukurutzeta, Muneta, Arrikurutz and Arno. In Vizcaya, the Kalamua, Urko, Mendibil, Oiz, Bizkargui and Berriaga mountains. On the other side of the Bilbao estuary, the Sasiburu mountain range and the Triano mountains.

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