Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Built Environment (hierarchy name)
4. Settlements and Landscapes (hierarchy name)
5. landscapes (environments)
6. natural landscapes
7. landforms (terrestrial)
8. fluvial landforms

Anotations

Scope note:

Deep, steep-sided land depressions, often having a river at the bottom; common to arid and semi-arid areas. Distinct from "valleys (landforms)," which tend to have a flattish landscape rather than high, precipitous slopes. Distinct from "gorges (landforms)," which tend to be smaller, narrower, and more rocky.