Hierarchy classification:

1. top of the aat hierarchies
2. Activities Facet
3. Processes and Techniques (hierarchy name)
4. [processes and techniques by specific type]
5. condition changing (processes)
6. surface or structural changes

Anotations

Scope note:

Describes a process of weathering in which the outer shell of rock becomes more resistant to erosion than its interior. Case hardening occurs by strengthening the exterior shell of the rock or by weakening of the rock's interior. In materials such as sandstone a greater accumulation of cements holding individual grains together at the surface causes shell strengthening. Case hardening in crystalline rock takes place when bonds are broken in the interior through chemical weathering.