Alpine glacial erosion, through overdeepening of valleys, may lead to structural collapse of the valley sides and mountain crest along small normal faults. Such features, known as sackungen, are described from crystalline rocks of the Alps and Rocky Mountains. Sackungen are reported herein for the first time from sedimentary bedrock of the Culebra Range of the Sangre de Cristo Mountains in south-central Colorado. The examples include small and large valley-side ridges and a double-crested mountain ridge. In all cases, the sackungen trend parallel to valleys sides or ridge crests above the limit of glaciation. Sackung deformation may involve both brittle and ductile mass movements of bedrock, which were probably aided by ice in subsurface joints. Seismic activity may have contributed to formation of sackungen in the Culebra Range. Sackungen are examples of glaciotectonic features created in hard bedrock under the impact of glaciation.