Spain's Central Plateau: Formation and Features

The Plateau

The Plateau is a high-altitude morphostructural unit that constitutes half of the peninsular relief units. Extensive plains alternate with hilly areas. The Alpine Orogeny caused the slope of the plateau towards the Atlantic Ocean. The Central System divides the plateau into two: the Northern Sub-Plateau and the Southern Sub-Plateau. These subunits were formed during downhill movement.

The Northern Sub-Plateau

It is situated within the northern half of the peninsula. Bordered to the northwest by the Galician-Leonese Massif, on the north by the Cantabrian Mountains, east by the Iberian System, and west by the gorges of the Douro and its tributaries. Its average altitude is 750m and it is crossed by a network of rivers, primarily the Douro.

• The Sedimentary Basin of the Duero

  It's a basement in that sector that, as a result of the Alpine Orogeny, sank deep. The basin became an inland lake and was replenished during the Tertiary and Quaternary periods. The rivers of the sedimentary basins carved river terraces, which are flat as banks. This area is dominated by clay lithologies. The landforms are simple two-level plains, moors, and countryside. Sometimes, hills are present in the plains. Limestone is prominent in the eastern half of the basin. The plains are located in the land of fields and pine forests.

• The Western Peneplain

  A peneplain is a gently undulating plain with low slopes, a result of the razing of an ancient mountainous terrain. They belong to the siliceous lithologic domain of granites and shales. These erosion surfaces have inselbergs, formed by resistant rock. They are located in the western sector of the Northern Sub-Plateau in Salamanca and Zamora.

The Southern Sub-Plateau

It is located in the southern half of the peninsula. Bordered on the north by the Central System, east by the Iberian System, south by Sierra Morena, and west by the Extremadura peneplain. It has an altitude of around 650m.

• The Sedimentary Basin of the Southern Sub-Plateau

  It has aspects in common with the Duero basin: the same geological origin, clay lithologies dominate in both, and vast plains are predominant. However, it has unique features: less symmetry and more hills. The Mountains of Toledo fragment this unit into two river basins: the Tagus to the north and the Guadiana to the south.

• The Peneplain

  Erosion surfaces are carved on the primary plinth, in which isolated outcrops of quartzite and inselbergs stand out. In the field of Calatrava.

The Mountainous Interior Units

The Central System

It is configured as a massive ancient Germanic-style mountain range. The Central System is divided into several groups. The Sierra de Gata and the Rock of France form a more western section and do not exceed 1,800 m in altitude. The Sierra de Gredos and the Sierra de Guadarrama are situated in the center. At the eastern end is the Sierra de Somosierra. It is a long and very close unit. The lithology is silica. In the remote mountains, metamorphic materials predominate, while in the central mountain ranges, granites dominate. The tops of the hills are soft and flat. Sometimes more abrupt and sheer forms appear, such as the peak or Galayos, carved on the granite in the Sierra de Gredos. In the higher elevations of Gredos and Guadarrama, there are traces of glaciation.

The Mountains of Toledo

They are located in the center of the Southern Sub-Plateau. Its genesis is a block socket subsequently destroyed in a complex fractured horst and graben system after the Alpine orogeny. It is modeled on Paleozoic quartzite and slate materials, which offer a typical Appalachian relief.