Geomorphology and Mountain Systems of the Iberian Peninsula

Geomorphology of the Campinas

The Campinas are vast, undulating landscapes with slopes lacking escarpments. They formed on clay and sand, resulting in elongated hills and wide valleys, rarely featuring an actual riverbed. These plains vary in altitude (700–1000 m), genesis, and location:

• Tierra de Campos: Located in the river valleys originating from the mountains, formed by impermeable clay excavation and interrupted by rapid, shallow lagoons.
• South of the Duero Campinas: Known as "Pine Land," these are covered with sand brought from the mountains by wind, even forming dunes. This includes the Arevalo-Madrigal countryside.
• Marginal-Campinas: Narrow strips located between the moors and mountains.
• Detrital-Platform: Characterized by alluvium and highlighted river terraces.

The Land of Medina

The Land of Medina features six levels of terraces with a total drop of 120 m, landing close to the watersheds and isolated hills on the highest points.

Ridge Mountains and Tectonic Activity

These formations resulted from Tertiary faults caused by the reactivation of the old basement and the folding of material deposited at the edges during the Secondary era.

Galaico-Leonese Massif

Located at the NW angle of the basement, it is fractured and unbalanced, featuring raised and sunken blocks. It consists of Paleozoic materials with low, rounded peaks. Key ranges include Segundera, Cabrera, and Los Ancares. The Leon Mountains, formed by fractured granite blocks, created the Bierzo rift valley, which is the most significant.

Cantabrian Mountains

This range consists of two distinct sectors:

• Asturian-Massif (West): The western part presents an Appalachian relief. The eastern part features a powerful carboniferous limestone outcrop, such as the Picos de Europa, containing the highest peaks shaped by glacier and periglacial modeling.
• Eastern Sector: Characterized by downhill folding from powerful Cretaceous sedimentary thicknesses resulting from marine regression. It features classic Jurassic relief with anticlines, synclines, and relief inversion.

Cordillera Ibérica

Composed of secondary materials and Paleozoic blocks, such as the break in the Moncayo. Secondary materials remain high due to the Paleozoic units themselves.

• Northern Mountains: These have a remarkable impact, dividing the basins of the Duero and Ebro. On the southern side, folds are eroded, amplifying the effects of reverse faults and bending stress. In central and northeast Soria, large limestone platforms and eroded Tertiary basins like Almazán are found.

Two branches follow a NW-SE direction toward the Mediterranean:

• Sierra de Albarracín: Includes the external or Aragonese saws and the Gúdar Javalambre limestone (both 2020 m), with abundant carvings and large poljes in their higher sectors.
• Jiloca Rift Valley: Separates both branches, containing recent and Quaternary materials. It widens to the north in the Calatayud depression, where Tertiary infilled material is arranged in gullied platforms and tables.

Sierra Morena

An abrupt step that separates the Meseta Central Ibérica (MCI) from the Guadalquivir valley. It is a large deflection of the basement, fractured in many places.