Geol. Forms: 6 tuph, 7–8 (9 dial.) tuft, (8 tufft), 7– tuff, (9 tuf). [ad. 16th c. F. tufe, tuffe, (R. Estienne) tuf, Cotgr. tuf, tuffe, ad. It. tufo ‘a kind of soft, crumbling, or mouldring stone to build withall’ (Florio):—L. tōfus, TOPHUS, q.v. The change of gender in obs. F. tuffe (= tufa) has not been explained. Tuft follows the better known TUFT sb. (where also the t is an addition).]
1. Any light porous cellular rock; = TUFA. (But there is a recent tendency to differentiate tuff from TUFA, and restrict it to ‘volcanic tuff.’)
a. Calcareous (or calc) tuff: see TUFA 1 a and quot. 1816.
1569. Stocker, trans. Diod. Sic., II. xliv. 99/2. With their axes and hatchets they cut thereof as a man shoulde do on a Tuph or softe Stone.
1603. [see tuff stone in 2].
1744. Platt, in Phil. Trans., XLIII. 266. A rocky petrified Substance,… by the Miners called Tuft.
1785. Barker, ibid., LXXV. 353, note. Tuft is a stone formed by the deposit left by water passing through beds of sticks, roots, vegetables, &c. of which there is a large stratum at Matlock Bath.
1816. Accum, Chem. Tests (1818), 166. When these waters suddenly lose the excess of carbonic acid … essential to the solution of the lime, there is an irregular precipitation; hence those tender calcareous cellular stones, and calcareous spongy tuffs.
1839. Ure, Dict. Arts, 771. Calcareous tuf consists of similar incrustations made by petrifying rivulets running over mud, sand, vegetable remains, etc.
1843. Portlock, Geol., 213. As calc tuff, it [carbonate of lime] is of very frequent occurrence throughout the primary and secondary district.
1881. Raymond, Mining Gloss., Tuff or Tufa, a soft sandstone or calcareous deposit.
(b) 1893–4. Heslop, Northumbld. Gloss., Tuft, a bed of fine-grained, siliceous stone, like ganister, which occurs in the carboniferous series below the Great Limestone. It is also known as water sill.
b. Volcanic tuff, a tuff produced by the consolidation of volcanic ashes and other erupted material.
1815. W. Phillips, Outlines Mineralogy & Geol. (1818), 187. Pumice, obsidian or volcanic glass, slime called volcanic tuff,… are also the products of volcanic eruptions.
1839. Darwin, Voy. Nat., xvii. (1852), 373. Craters, composed of the soft and yielding tuff.
1841. Trimmer, Pract. Geol., 173. Aqueous lavas, which, as they consolidate, form rocks of an earthy appearance, known by the name of volcanic tuff or tufa.
1850. Ansted, Elem. Geol., Min., etc., Gloss., Tufa, Tuff, an Italian name for a variety of volcanic rock of earthy texture,… made up … of fragments of volcanic ashes.
1881. Judd, Volcanoes, v. 117. The tuffs covering the city of Pompeii consist of numerous thin layers of lapilli and volcanic dust.
1914. Brit. Mus. Return, 229. Volcanic lapilli and palagonite-tuff from Monte Brazil, Terceira, Azores.
c. Trap-tuff: see quot.
1833–4. J. Phillips, Geol., in Encycl. Metrop. (1845), VI. 768/1. Aggregations of the disintegrated … materials of trap rocks are generally known under the vague name of trap tuff and compared with volcanic tuff.
2. attrib. and Comb., as tuff bed, block, cone, crater, mountain, stone [F. pierre de tuffe (Cotgr.)], tuff-wacke; tuff-like adj.
1854. Hooker, Himal. Jrnls., I. ii. 44. Enormous *tuff beds are deposited on the sandstone.
1864. J. Hunt, trans. Vogt’s Lect. Man, x. 262. In these *tuff blocks, in the vicinity of the town of Puy, are found the mammoth and the rhinoceros with a bony nasal septum.
1881. Judd, Volcanoes, 118. Finely-stratified *tuff-cones.
1839. Darwin, Voy. Nat., xvii. (1845), 376. To the south of the broken *tuff-crater.
1880. Academy, 20 Nov., 370. They [certain Chinese rocks] exhibit *tuff-like characters.
1861. E. T. Holland, in Peaks, Passes & Gl., Ser. II. I. 9. A high range of *tuff mountains.
1603. Owen, Pembrokeshire (1892), 80. There is *Tuff Stone found in the Mountaine over Newport.
c. 1640. J. Smyth, Lives Berkeleys (1883), I. 309. Fetching … the Tuft stone from Dursley by land.
1802. Brookes’ Gazetteer (ed. 12), s.v. Lugano, Most of the houses are built of tufstone.
1822–7. Good, Study Med. (1829), I. 61. Tufa or tuffwacke, as Schmeisser calls it, and tarras, which are compounds of iron, alumine, silex, and carbonate of lime.
1847. Leitch, trans. C. O. Müller’s Anc. Art, § 271 (1850), 303. Pozzolana (an earthy tuff-wack).
