Iberian Peninsula Mountain Systems and Depressions
Iberian Peninsula: Mountain Systems and External Depressions
The Iberian Peninsula features diverse mountain systems and external depressions. Here’s a breakdown:
Iberian System
Located in the eastern part of the plateau, the Iberian System separates it from the Ebro basin and the plains of Valencia. This system stretches approximately 400 km in a northwest-southeast direction, from the Sierra de la Demanda to the foothills of Iberian Valencia. It is divided into two sections:
- Northern Sector: Includes the highest mountains of the system, such as the Sierra de la Demanda, Urbión peaks, and Moncayo.
- Southern Sector: Extends into the Mediterranean. The Rift Valley Jiloca River separates this section into two branches: the Castilian interior, featuring the Sierra de Gúdar and Mastership.
Systems Outside the Plateau
Coastal Catalan Cordillera
This unit separates the Iberian Peninsula from the northeast. Faults separate it from the Pyrenees, sometimes leading to volcanic activity. It forms part of the Alpine mountain chain of the Iberian Peninsula and extends over 400 km.
Pyrenees
Within this network, three distinct areas can be identified:
- Axial Area: Home to the highest peaks, exceeding 3000 meters, such as Aneto (3404m) and Monte Perdido (3355m).
- Pre-Pyrenees: Features lower heights and gentler shapes.
- Basque Mountains: An extension of the western Pyrenees, serving as a link between them and the Cantabrian Mountains.
Betic Systems
This is a large mountainous chain in southeastern Iberia. Its formation resulted from the compression of the African and Eurasian plates during the Tertiary period. It extends from the southwest to the northeast and re-emerges in Ibiza and Mallorca.
From the coast inland, three areas are distinguished:
- Peribetic Alignment: Includes the highest altitudes of the Iberian Peninsula, such as Mulhacén (3478m) and Veleta peak (3382m).
- Intrabetic Trench: Formed by a series of depressions of tectonic origin, where erosion materials are deposited, creating a badlands landscape in areas such as Antequera, Granada, Guadix, and Baza.
- Subbetic Cordillera: Consisting of secondary-age materials folded during the Tertiary period, presenting lower altitudes, such as the Sierra de Cazorla and Segura. At the northern end of the alignment, the prebeta (Sierra de Espuña in Murcia and Alicante Sierra de Aitana) is in contact with the Plateau.
External Depressions
There are two main external depressions: the Ebro and the Guadalquivir. Both are located between major mountain ranges, with an average altitude lower than 300 meters. Their origins are linked to the formation of the surrounding mountain ranges.
Ebro Depression
It occupies the site of the old Ebro Massif, which sank during the Alpine Orogeny as the Pyrenees rose. The Catalan coastal range closed off marine access, while the Ebro made its way into the Mediterranean in the late Tertiary period. Consequently, its sediments are of both marine and continental origin.
Guadalquivir Depression
Runs parallel to the Betic systems. Originally open to the sea, it later became a lake shore and then a swamp. From the interior to the coast, the landscape transitions from the hills and gently rolling hills of Úbeda and Jaén to the plains of Córdoba and Seville, and finally to the coastal plains where the Guadalquivir marshes are separated by an extensive Atlantic coastal ridge.