tuff
/tʌf
/noun [mass noun]
A light, porous rock formed by consolidation of volcanic ash.Among the 30 different types of stone recognized are varieties of diorite, granite, bedded tuff, sandstones, limestones, and tufa....
- Lenses incorporate varicoloured tuffaceous cherts intercalated with tuffaccous mudstone and tuff.
- The lower series consists of alternating basalt lava, tuff breccia, tufite, and siliceous rock, whereas the upper one is dominated by diabase.
Derivatives
tuffaceous
- Further up section the geology is dominated by a succession of unmetamorphosed but strongly fractured and veined blocky andesites, basalts and tuffaceous rocks.
- In addition, there are tuffaceous (volcanic ash) layers at various horizons throughout the Green River Formation.
- Built of uniformly gray, granular volcanic tufa, or peperino, the courtyard was completed by 1579, as recorded in the building documents.
Origin
Mid 16th century: via French from Italian tufo, from late Latin tofus, Latin tophus (see tophus).