Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. combination inorganic/organic material
7. soil
8. [soil by composition or origin]
9. sediment

Anotations

Scope note:

A nitrogen-rich, combustible, sludge-like black sedimentary deposit that occurs as a result of the decomposition of microorganisms in anaerobic conditions on the bottoms of lakes and seas. Compressed into hard rock, sapropel becomes oil shale or sapropelic coal.