| 释义 |
clay-slate
An argillaceous sedimentary rock, of bluish or greenish colour, composed of indurated clay, characterized by being extremely fissile, the cleavage being entirely distinct from, and in origin subsequent to, the original stratification, which it crosses at all angles, while parallel to itself over large areas of country.
In Great Britain the beds of clay-slate belong to the Cambrian and Silurian series, and supply ordinary roofing slates as well as slates for school use, and slate pencils. In other parts there are masses of clay-slate of very different ages, some supposed to be as recent as the chalk formation.
1837Penny Cycl. VII. 247/1 Clay slate. 1846McCulloch Acc. Brit. Empire (1854) I. 351 There is also a strip of clay-slate. 1869E. A. Parkes Pract. Hygiene (ed. 3) 19 The purest water from granitic or clay-slate districts. 1878Lawrence tr. Cotta's Rocks Class. 256 The characteristic feature of clay-slate..is that its slaty cleavage..is altogether independent of its original bedding. 1881Jukes Sch. Manual Geol. 325 In the Andes of South America vast masses of dark clay-slate, just like those found in our Silurian formations..having Cretaceous fossils in some parts, and in other beds fossils more like Oolitic ones. |