Key takeaways
- Talus is a field of large, angular rock blocks piled at the base of cliffs and steep slopes.
- It forms from rockfall and freeze-thaw weathering breaking rock off the slopes above.
- Blocks are big enough to step on (vs finer, slide-prone scree).
- Cross it deliberately: test blocks, step on stable ones, and watch for shifting or 'tippy' rocks.
From French 'talus' (slope), from Latin 'talutium'.
What talus is and how it forms
Talus is the sloping apron of large, angular rock fragments that collects at the foot of cliffs and steep mountainsides. It forms over time as freeze-thaw weathering and rockfall pry blocks loose from the rock faces above, which tumble down and pile up. The result is a field of blocks ranging from football- to car-sized.
Talus vs scree
The key difference from scree is size: talus blocks are large enough to step on individually, while scree is finer rock and gravel that slides. That makes talus more stable to walk but harsher if a block shifts. See scree vs talus.
Crossing a talus field, a mountaineer steps from one large, embedded block to the next, testing each before committing weight and avoiding perched ‘tippy’ rocks — while the group spreads out so a dislodged block can’t strike anyone below.
Traveling talus safely
Move deliberately with balanced weight, favor big stable rocks, and avoid perched blocks. In a group, manage spacing so a kicked-loose rock doesn’t hit those below, and use trekking poles for balance. Talus near glaciers grades into moraine.
The bottom line
Talus is the large-block rubble at the base of mountain slopes — more stable than scree but unforgiving when a block tips. Cross it with deliberate, balanced steps on solid rock, mind your spacing in a group to avoid knocking rocks onto others, and talus fields become a routine, manageable part of alpine travel.
Frequently asked questions
What is talus?
Talus is the apron of large, angular rocks that builds up at the foot of cliffs and steep mountainsides, created as rockfall and freeze-thaw weathering break material off the slopes above. The blocks are generally big enough to step on one at a time.
What's the difference between talus and scree?
It's mainly size. Talus is made of large blocks you step across; scree is smaller, looser rock and gravel that slides underfoot. Talus is more stable to walk but punishing if a block shifts; scree is unstable but can be descended by 'scree skiing'. See our scree vs talus comparison.
How do you safely cross a talus field?
Move deliberately and keep your weight balanced over your feet. Test blocks before committing weight, favor large, embedded, stable-looking rocks, avoid 'tippy' or perched blocks, and keep spacing in a group so a dislodged rock doesn't hit someone below. Trekking poles help with balance.
Sources
- Mountain landforms & geology — USGS
- Mountain travel skills — The Mountaineers