The Sculpture of Ice and Water

Glacial Legacies

Both mountain ranges bear the unmistakable marks of ice age glaciation, though manifested differently. During the last glacial maximum 20,000 years ago, the Alps lay buried beneath an ice cap that sent massive glaciers flowing down every major valley, some reaching as far as present-day Lyon. These rivers of ice carved the characteristic U-shaped valleys, excavated lake basins, and sculpted the sharp peaks and ridges known as arêtes and horns.

Today's Alpine glaciers, though much reduced, remain active landscape sculptors. The Mer de Glace, France's largest glacier at 7 kilometers long, continues its slow descent from the Mont Blanc massif, though it has lost over 700 meters in length since the 19th century. Smaller glaciers persist on north-facing slopes throughout the Alps, each contributing to the ongoing erosion and sediment transport that shapes valleys below.

The Pyrenees experienced less extensive glaciation, with ice confined mainly to valley glaciers rather than a continuous ice cap. This created a different landscape signature—cirques (bowl-shaped depressions) are particularly numerous and well-preserved, especially in the central Pyrenees. The famous Cirque de Gavarnie, with its 1,500-meter walls and spectacular waterfalls, represents one of Europe's most perfect examples of glacial sculpture.

Living Rivers

Mountain waters define life in both ranges. The Alps serve as Europe's water tower, with rivers like the Rhône, Rhine, and Po originating in French Alpine glaciers and snowfields. The hydrological regime follows seasonal patterns—low flows in winter when precipitation falls as snow, dramatic increases during spring snowmelt, and variable summer flows depending on glacier melt and thunderstorms.

Pyrenean rivers, known locally as gaves in the west and rivers in the east, display different characteristics. Fed more by rainfall than glacier melt, they show greater year-round consistency but can experience violent floods during autumn storms. The gave system has carved spectacular gorges through limestone plateaus, creating dramatic landscapes and providing renewable energy through numerous hydroelectric installations.

Both ranges feature remarkable karst hydrology where limestone dominates. Water disappears into underground networks, traveling through caves and fissures before emerging in massive springs. The Fontaine de Vaucluse, fed by Vercors groundwater, ranks among the world's most powerful karst springs. These hidden water networks support unique cave ecosystems and create challenges for water resource management.