Truncated spurs are steep-sided cliff formations created when glaciers erode pre-existing interlocking spurs in river valleys.
Formation Process
Originally, rivers carve V-shaped valleys with interlocking spurs – rock ridges that extend into the valley, forcing water to zigzag around them. During glaciation, valley glaciers move in straight paths down valleys, unlike meandering rivers. The massive ice mass uses abrasion and plucking to bulldoze away the protruding rock formations, creating vertical cliff faces where spurs once extended.
Location and Characteristics
These erosional features display smooth, polished surfaces with angular terminations, contributing to the characteristic U-shaped profile of glaciated valleys. Truncated spurs are found in regions experiencing significant past glaciation, including the European Alps and Rocky Mountains, Scottish Highlands, Scandinavian fjords, Patagonian landscapes, and Himalayan valleys.
They serve as diagnostic indicators of former glacial activity and demonstrate the superior erosional power of ice compared to running water.