They are built of large slabs of slate and granite. Geologically, Plymouth has a mixture of limestone, Devonian slate, granite and Middle Devonian limestone. The scheme was constructed in the abandoned Dinorwic slate quarry. It is particularly well suited for slate and sandy clay soil. Roofs are traditionally constructed from Alpine rocks such as pieces of schist, gneiss or slate. Shingle is a corruption of German schindle (schindel) meaning a roofing slate. Belly colour white with pale slate undercolour. The entire left caucus slate was then elected. His eyes are a shade of slate blue. Bardel has a rolling slate of projects in production. The company started with a completely blank slate. Thus they truly are a blank slate. The meeting ended at 4&colon;45pm having agreed on a full slate of candidates. The word "slate" is also used for certain types of object made from slate rock. Manufacturing of slate blackboards began by the 1840s.