oil-base mud
31Drilling rig — For a detailed diagram of a Petroleum drilling rig, see List of components of oil drilling rigs. Drilling rig preparing rock blasting …
32Devonian Period — Interval of geologic time from 417 to 354 million years ago; it was the fourth period of the Paleozoic Era. During the Devonian, a giant continent was situated in the Southern Hemisphere (see Gondwana), and other landmasses were located in the… …
33Cold seep — Marine habitats Tube worms are among the dominant species in one of four cold seep community types in the Gulf of Mexico. Littoral zone …
34Yemen — /yem euhn, yay meuhn/, n. 1. Republic of, a country in S Arabia, formed in 1990 by the merger of the Yemen Arab Republic and the People s Democratic Republic of Yemen. 13,972,477; 207,000 sq. mi. (536,130 sq. km). Cap.: (political) San a. Cap.:… …
35building construction — Techniques and industry involved in the assembly and erection of structures. Early humans built primarily for shelter, using simple methods. Building materials came from the land, and fabrication was dictated by the limits of the materials and… …
36international relations — a branch of political science dealing with the relations between nations. [1970 75] * * * Study of the relations of states with each other and with international organizations and certain subnational entities (e.g., bureaucracies and political… …
37Iraq — /i rak , i rahk /, n. a republic in SW Asia, N of Saudi Arabia and W of Iran, centering in the Tigris Euphrates basin of Mesopotamia. 22,219,289; 172,000 sq. mi. (445,480 sq. km). Cap.: Baghdad. Also, Irak. * * * Iraq Introduction Iraq Background …
38Nigeria — Nigerian, adj., n. /nuy jear ee euh/, n. a republic in W Africa: member of the Commonwealth of Nations; formerly a British colony and protectorate. 107,129,469; 356,669 sq. mi. (923,773 sq. km). Cap.: Abuja. Official name, Federal Republic of… …
39Europe, history of — Introduction history of European peoples and cultures from prehistoric times to the present. Europe is a more ambiguous term than most geographic expressions. Its etymology is doubtful, as is the physical extent of the area it designates.… …
40Germany — /jerr meuh nee/, n. a republic in central Europe: after World War II divided into four zones, British, French, U.S., and Soviet, and in 1949 into East Germany and West Germany; East and West Germany were reunited in 1990. 84,068,216; 137,852 sq.… …
