Geology and Relief of the Iberian Peninsula

Spain is geographically softened, like an inaccessible castle. The Iberian Peninsula has the highest average altitude in Europe, second only to Switzerland. The coast is often surrounded by walls, and the citadel would be the plateau, with a mean altitude of 700 meters. This plateau is the higher, more archaic, and more exposed part of the peninsula. However, even within this core, inaccessibility occurs again, as if there were more castles within the main one.

Geological Evolution

The geological evolution of the Iberian Peninsula is primarily due to its location between the African and European plates. There are several geological land surface sets in Iberia:

Geological Sets

• Very Ancient Materials (Precambrian or Archaic): Heavily affected by even pre-Primary orogenies.
• Paleozoic Regions: Deformed Primary fields from the Hercynian orogeny during the Primary epoch.
• Rock (Crag) of the Secondary and Tertiary: Folded or broken by the Alpine Orogeny.
• Lots with Alpine Orogeny: Sedimentary strata folded after the Alpine Orogeny.

All sets listed above have been conditioned by a series of movements that the continental plates have made over time. There are at least three types of movements:

Plate Tectonic Movements

• Divergent Plate Separation: Logically, oceans are opened or submerged in these areas. Example: The Atlantic Ocean.
• Convergent Movements (Approaching or Collision): Occur when tectonic forces compress, fold, and lift the crust, forming new mountain ranges. Example: The Pyrenees formed by Alpine folding.
• Side-Slip Movements: Plates may not collide or diverge but simply slip past each other. This causes horizontal or tear faults.

Geological Stages of the Iberian Peninsula

Iberia Precambrian (Archaic)

This era is represented by the peninsula's location between two plates, the African (Gondwana) and the Paleoeuropean, with the Sea of Tethys in between.

Iberia Paleozoic (Primary)

This stage had little impact on the Iberian Peninsula, at least during the period known as the Cambrian.

Iberia Mesozoic (Secondary)

This was a period favored by tranquility and erosion, with flooding forming hard rock areas and the Pyrenees and Andalusia being infused by two ocean trenches.

Iberia Cenozoic (Tertiary)

During this stage, movements of the Alpine orogeny occurred across the entire region, lifting marine sediments in the Pyrenees and Andalusia, as well as in the Ebro area sinks.

Iberia Quaternary

In the post-Alpine era, the most important event was the tilting of the plateau to the west, directing large river systems towards the Atlantic and permanently settling the rivers.

Morphostructural Relief Units

There are three major morphostructural units:

1. Old and Paleozoic Beds: Remnants of old mountain ranges worn down by erosion into peneplains, although some have been rejuvenated by Alpine folding, such as the Sierra Morena.
2. Alpine Ranges: Young mountains raised to high altitudes by the Alpine movement, the last great movement in Earth's history. They are not worn down because they are young and are predominantly limestone, belonging to this type of relief, such as the Pyrenees.
3. Depressions or Post-Alpine Sedimentary Basins: Sediment-filled depressions like those in the Ebro basin or the interior of the plateau, such as the Douro basin, although the latter is shallower.