ABSTRACT
Geological materials have been used for building for much of human history. Strong rocks form dimension stone for walls (Fig. 8.1). Thin-bedded flags or cleaved slates are suitable for roofs. Clay can be shaped, then sun-baked or kilned to make bricks and tiles. Clay can be mixed with limestone, then fired to make cement. Cement, sand and water form mortar for bonding stone and brick. Gypsum is heated to produce plaster. Only timber matches rocks in importance as a traditional building material.
