Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. inorganic material
7. rock (inorganic material)
8. [rock by form]

Anotations

Scope note:

A large, loose residual mass of stone left after the erosion of a once continuous bed or layer; often used to specifically refer to one of the large sandstone blocks scattered over the English chalk downs.