Catalonia and Andalusia: Geography and Relief of Key Regions

Catalan Coastal Mountain Range

The Catalan Coastal Mountain Range extends from the Pyrenees to the Ebro Delta, in a northeast-southwest direction. The sector with siliceous material is formed by the rest of the Catalan-Balearic solid. The southern sector includes Montseny. The sector with calcareous materials includes the mountains of Montserrat and Montsant.

Ebro Depression

The Ebro Depression, with a northwest-southeast direction, originates in the Cantabrian Mountains. However, it mainly flows through the Pyrenees and the Iberian System, leading to the Catalan Coastal System in the northeast and forming the main delta of the peninsula. The relief of the depression is derived from eroded material from the surrounding mountains. In turn, erosion has been carried out by watercourses. The Ebro was a solid that sank during the primary era's Alpine movements in the Tertiary period. It was progressively filled and eroded. Clay loam and gypsum predominate. The Ebro River, at its mouth, forms the most extensive delta of the peninsula, a consequence of the large amount of eroded material transported, especially from the Pyrenees.

Betic System

The Betic System is a set of units formed by two mountainous channels, the Subbetica and Penibetica, and a series of internal basins and depressions that separate them. In addition, Gibraltar (sandstone) and the Sierra de Gata (volcanism) are located in this system.

Penibetica

The Penibetica runs parallel to the Mediterranean coast, in an east-west direction. It belonged in the mid-Tertiary period to the massive continent of Betico Godwana, from which it separated by the Strait of Gibraltar. Siliceous materials predominate in the Malaga Mountains, the Sierra Nevada mountain range, or other areas like Filabres. Limestone materials raised from the seabed are found in the White Highlands and the Red Highlands. The maximum heights are found in Mulhacen in the Sierra Nevada.

Subbetica

The Subbetica runs in a northeast-southwest direction, starting in the provinces of Cadiz and Seville, continuing through Cordoba and Jaen, extending into the provinces of Murcia and Alicante, and surfacing in the Balearic Islands. It is formed by limestone materials, although with different morphology. In the provinces of Malaga, Cordoba, and Jaen, there are sheets. From Alicante, there are marine uplifts. Notable are the former branches of Sierra Rute, Cabra, Priego, Cazorla, and Segura.

Interior Basins

The interior basins are small depressions separating the Penibetica and Subbetica. Their altitude is over 500 meters, lower in the west and higher in the east. The main basins are: Loja, Antequera, Ronda, Guadix, and Baza. They have been formed by the sedimentation of materials from the surrounding mountains. The Genil, the main tributary of the Guadalquivir, flows through them.

Guadalquivir Depression

The Guadalquivir Depression has a triangular shape, similar to the Ebro, but unlike the Ebro, it is open to the Atlantic Ocean. It runs in a southwest-northeast direction, originating in the Sierra de Cazorla and leading to Sanlucar de Barrameda. It was formed at the end of the Tertiary period by the filling of materials from upland erosion. What was once a marine gulf in the mid-Tertiary period disappeared. Two thousand years ago, it was a lake, and now it is the largest marshland in Spain. It is formed by clay, marl, and sand materials in the final course.