Orig. and chiefly Sc. [Origin unascertained: cf. THILL2 in similar sense.]
1. A term applied to a stiff clay, more or less impervious to water, usually occurring in unstratified deposits, and forming an ungenial subsoil. Originally a term of agriculture in Scotland.
1765. A. Dickson, Treat. Agric., II. (ed. 2), 222. They [plowmen] are so inattentive, as to leave good soil in some places, and turn up till in others.
1799. J. Robertson, Agric. Perth, 19. On the declivities of almost all the hills a strong stiff till abounds. Ibid., 477. Like all the land on the south aspect of the Seedlaws being a red till, capable of high cultivation and in most places approaching to the nature of loam.
1805. Forsyth, Beauties Scotl., II. 66. Till,… is in universal use among farmers,… implying very various mixtures of mineral substances placed under the fertile mould…. In general,… a hard clay of any sort, which in a very slight degree admits the passage of water, and is impenetrable by the roots of plants.
1816. Scott, Antiq., iv. Placing paving-stones beneath the tree when first planted … a barrier between his roots and the unkindly till. Ibid., xxiii. We’re down to the till now,… and the ne’er a coffin or ony thing else is here.
fig. 1831. Brewster, Nat. Magic, xi. (1833), 287. It may lie long unproductive in the ungenial till of human knowledge.
b. In the majority of cases this clay belongs to the Glacial or Drift period, and in geological use ‘till’ has the specific sense ‘boulder clay.’
1842. Darwin, in Life & Lett. (1887), I. 300. A contribution to the Geological Society, on the boulders and ’till’ of South America.
1851. Jrnl. R. Agric. Soc., XII. I. 281. This clay … rests upon ‘till,’ or boulder clay.
1863. Lyell, Antiq. Man, xii. (ed. 3), 218. Erratics of Scandinavian origin occur chiefly in the lower portions of the till.
1863. A. C. Ramsay, Phys. Geog., xxiv. (1878), 384. Much of the Lower Boulder-clay is known as ’Till’ in Scotland.
2. Hard or soft shale; app. = THILL2 dial.
1672. G. Sinclair, Misc. Obs. Hydrostaticks, 260. And so we find in Digging or Sinking, that after the Clay is past, which keeps no course, all Metals, as Stone, and Tilles (which are Seems of black Stone, and participat much of the nature of Coal), ly one above another, and keep a regular Course.
1831. W. Patrick, Plants Lanark, Pref. 18. The stratum inself lies on a bed of till above the main coal.
3. Comb. Till-stone, a fissile shale, in coal-mines, etc.
c. 1830. Glouc. Farm Rep., 4, in Lib. Usef. Kn., Husb., III. A thin wet clay, of a most adhesive nature, covering the thin fissile till-stone.
