Morphostructural Units of the Iberian Peninsula
Morphostructural Units of the Iberian Peninsula, Balearic and Canary Islands
Large Morphostructural Relief Units
The Peninsular Plateau
The Peninsular Plateau is a high plain located between 600-800 meters. Formed in the Paleozoic Era by erosion of the ancient Hesperian Massif (which emerged during the Hercynian orogeny), the plateau was later deformed in the Tertiary Period during the Alpine orogeny. This resulted in three distinct units:
- Former Paleozoic Base: Located in the western peninsula, this unit features prominent silicate rock. The relief consists of peneplains and rugged hills.
- Interior Mountain Ranges: These include the Central System and the Montes de Toledo.
- Central System: This range divides the Meseta in half. Its most prominent peaks include Somosierra, Guadarrama, Gredos, Peña de Francia, and Gata.
- Montes de Toledo: This range divides the southern sub-plateau, separating the basins of the Tagus and Guadiana rivers. The most important peak is in the Guadalupe Mountains.
- Inland Sedimentary Basins: These basins, located in the northern and southern sub-plateaus, formed in the Tertiary Period as a result of the Alpine orogeny. They consist of moors, fields, and hills (e.g., Alcarria, Mesa de Ocaña, La Mancha).
- Moorlands: Elevated, flat areas.
- Campinas: Plains traversed by rivers like the Douro, Tagus, and Guadiana.
- Cuestas: Sloping areas between the moors and the fields.
- Northern Sub-plateau Basin: Higher and more uniform, belonging entirely to the Douro river basin and almost entirely enclosed by mountains.
- Southern Sub-plateau Basin: Lower, divided by the Montes de Toledo into the Tagus and Guadiana river basins, and open to the Atlantic Ocean.
Mountain Ridges of the Plateau
- Galaico-Leonese Massif: Formed in the Tertiary Period during the Alpine orogeny, this massif consists of Paleozoic materials. Its most prominent peaks are Segundera, Cabrera, and Los Ancares.
- Cantabrian Mountain Range: This range has two sectors:
- Western Sector (Asturian Massif): Formed in the Tertiary Period during the Alpine orogeny from Paleozoic materials.
- Eastern Sector (Cantabrian Mountains): Formed in the Tertiary Period by the folding of secondary materials deposited on the edge of the plateau. Its materials are primarily limestone.
- Iberian Range: This range also has two sectors:
- Northern Sector: Features peaks like Urbión (2235m), as well as the Demand and Moncayo mountains.
- Southeast Sector: Forks into the interior branch (Sierra de Albarracín and Serrania de Cuenca) and the exterior branch (Sierra de Javalambre and Gúdar).
Units Outside the Plateau
Depressions Outside the Plateau
- Ebro Depression: Parallel to the Pyrenees, bounded by the Iberian Range and the Coastal Cordillera Catalana. Initially occupied by the sea, it later became a large lake before opening again to the sea at the end of the Tertiary Period.
- Guadalquivir Depression: Parallel to the Baetic System, located between the Sierra Morena and the Atlantic Ocean. Initially open to the sea, it later transformed into a lake, then a shoreline, and finally, marshland.
The Pyrenean and Iberian foothills are flat, gently sloping hills located between the external and central depressions.
Mountain Ridges Outside the Plateau
- Pyrenees:
- Axial Zone: Features a rugged relief with peaks like Montes Malditos and Aneto.
- Pre-Pyrenees: Located south of the Axial Zone, formed during the Alpine orogeny. They have a softer, less pronounced relief and are divided into inner and outer ranges.
- Median Depression: A long, narrow depression separating the inner and outer Pre-Pyrenean ranges.
- Basque Mountains: An extension of the Pre-Pyrenees, these mountains are characterized by limestone crags and moderate heights.
- Coastal Cordillera Catalana: A transformation of the eastern Pyrenees. The northern half consists of Paleozoic materials, while the southern half is primarily limestone. The range is divided into two lines: one parallel to the coast and another inland, separated by a longitudinal depression.
- Baetic System: Consists of two mountain ranges:
- Penibaetic Range: Located along the coast, featuring Sierra Nevada with peaks like Mulhacén and Veleta.
- Subbaetic Range: Located inland, featuring the mountains of Grazalema, Ubrique, and Cazorla.