clay-slate

The rock which appeared here and there on the riverbank was an indurated clay-slate, sometimes crystalline, and thrown up almost vertically.

The Malay Archipelago 2004

These alternating masses are covered in the central parts by a great thickness of red sandstone, conglomerate, and calcareous clay-slate, associated with, and passing into, prodigious beds of gypsum.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

The short divide beyond the far bank of the Sirr is strewn with glittering mica-schist that takes the forms of tree-trunks and rotten wood; and with dark purple-blue fragments of clay-slate looking as if they had been worked.

The Land of Midian 2003

I have already said the mountain is composed of white quartz rock, and with it a little glossy clay-slate is associated.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

The central part of Tierra del Fuego, where the clay-slate formation occurs, is most favourable to the growth of trees; on the outer coast the poorer granitic soil, and a situation more exposed to the violent winds, do not allow of their attaining any great size.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

Some of the icebergs were loaded with blocks of no inconsiderable size, of granite and other rocks, different from the clay-slate of the surrounding mountains.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

The lower country consists of clay-slate and sandstone, containing fossils, very closely related to, but not identical with, those found in the Silurian formations of Europe; the hills are formed of white granular quartz rock.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

The surrounding islands all consist of conical masses of greenstone, associated sometimes with less regular hills of baked and altered clay-slate.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

I have already said the mountain is composed of white quartz rock, and with it a little glossy clay-slate is associated.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003

The harbour consists of a fine piece of water half surrounded by low rounded mountains of clay-slate, which are covered to the water's edge by one dense gloomy forest.

Journal of researches into the geology and natural history of the various countries visited by H.M.S. Beagle 2003