Environment, the complex of physical, chemical, and biotic factors that act upon an organism or an ecological community and ultimately determine its form and survival. The Earth’s environment is treated in a number of articles. The major components of the physical environment are discussed in the articles atmosphere, climate, continental landform, hydrosphere, and ocean. The relationship between the principal systems and components of the environment,…
Concrete, in construction, structural material consisting of a hard, chemically inert particulate substance, known as aggregate (usually sand and gravel), that is bonded together by cement and water. concrete Among the ancient Assyrians and Babylonians, the bonding substance most often used was clay. The Egyptians developed a substance more closely resembling modern concrete by using lime and gypsum as binders. Lime (calcium oxide), derived from limestone, chalk, or (where…
Brick and tile, structural clay products, manufactured as standard units, used in building construction. The brick, first produced in a sun-dried form at least 6,000 years ago and the forerunner of a wide range of structural clay products used today, is a small building unit in the form of a rectangular block, formed from clay or shale…
Hide, the pelt taken from a cow, steer, or bull of the bovine species, from the pelt of a horse, or from the integument of some other large adult animal. The pelts of smaller animals are commonly called skins—namely, sheepskins, goatskins, calfskins, etc. For the preservation and tanning of hides . Tanning Tanning, chemical treatment of raw animal hide or…
Marbles are used principally for buildings and monuments, interior decoration, statuary, table tops, and novelties. Colour and appearance are their most important qualities. Resistance to abrasion, which is a function of cohesion between grains as well as the hardness of the component minerals, is important for floor and stair treads. The ability to transmit light is important for statuary marble,…
Asbestos Asbestos, any of several minerals that readily separate into long, flexible fibres. Chrysotile, the fibrous form of the mineral serpentine, is the best-known type and accounts for about 95 percent of all asbestos in commercial use. It is a hydrous magnesium silicate with the chemical composition of Mg3Si2O5(OH)4. The other types all belong to the amphibole group of minerals and include…
Origins of agriculture, the active production of useful plants or animals in ecosystems that have been created by people. Agriculture has often been conceptualized narrowly, in terms of specific combinations of activities and organisms—wet-rice production in Asia, wheat farming in Europe, cattle ranching in the Americas, and the like—but a more holistic perspective holds that humans are environmental engineers who disrupt terrestrial habitats in specific ways. Anthropogenic disruptions such as clearing…
Igloo, also spelled iglu, also called aputiak, temporary winter home or hunting-ground dwelling of Canadian and Greenland Inuit (Eskimos). The term igloo, or iglu, from Eskimo igdlu (“house”), is related to Iglulik, a town, and Iglulirmiut, an Inuit people, both on an island of the same name. The igloo, usually made from blocks of snow and dome-shaped, is used only in the area…
Masonry Masonry, the art and craft of building and fabricating in stone, clay, brick, or concrete block. Construction of poured concrete, reinforced or unreinforced, is often also considered masonry. masonry The art of masonry originated when early man sought to supplement his valuable but rare natural caves with artificial caves made from piles of stone. Circular stone huts, partially…
Climate, conditions of the atmosphere at a particular location over a long period of time; it is the long-term summation of the atmospheric elements (and their variations) that, over short time periods, constitute weather. These elements are solar radiation, temperature, humidity, precipitation (type, frequency, and amount), atmospheric pressure, and wind (speed and direction). From the ancient Greek origins of the word (klíma, “an inclination or slope”—e.g., of…