Geological History and Morphostructural Relief of the Peninsula

1. Geological History and Morphostructural Relief

Landforms result from tectonic movements occurring within the Earth. The constant movement of these plates causes the crust to rise or sink, creating relief forms known as orogenic structures.

Erosion is the wearing down of relief through exposure to ice, water, wind, and biological activity, which constitutes the process of modeling. Eroded materials are subsequently deposited on the Earth's crust through sedimentation.

The Primary Era

The Hercynian orogeny occurred during this period, creating mountain ranges composed of siliceous rocks such as granite, slate, and quartzite. These ridges were later destroyed by erosion, becoming sockets. The resulting socket on the Peninsula leaned toward the Mediterranean.

The Secondary Era

This was a period of relative calm characterized by erosion and sedimentation. Sea penetration led to the deposition of soft materials—including limestone, sandstone, and marl—on the eastern edge of the socket. During this time, deep trenches in the areas of the modern-day Pyrenees and Betic Cordilleras were filled with large sediment deposits.

The Tertiary Period

The Alpine orogeny defined this era. Sediments in the Pyrenean and Betic regions were folded, rising to form the Pyrenees and the Betic Cordilleras. Pre-Alpine depressions, such as the Ebro and Guadalquivir, were created by subsidence during intense tectonic activity.

• Drainage: The plateau tilted toward the Atlantic, causing most peninsular rivers to flow into the ocean.
• Mountain Formation: Soft materials deposited during the Secondary Era were folded by tectonic movements, giving rise to the Cantabrian Mountains, the Iberian System, and Sierra Morena.
• Fractures and Faults: The plateau, composed of rigid siliceous materials, developed fractures and faults where the Earth's crust split into blocks.