light penetration depth
51harbours and sea works — Introduction harbour also spelled harbor any part of a body of water and the manmade structures surrounding it that sufficiently shelters a vessel from wind, waves, and currents, enabling safe anchorage or the discharge and loading of… …
52Wreck diving — Diver at the wreck of the Hilma Hooker, Netherlands Antilles. Wreck diving is a type of recreational diving where shipwrecks are explored. Although most wreck dive sites are at shipwrecks, there is an increasing trend to scuttle retired ships to… …
53Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… …
54KABBALAH — This entry is arranged according to the following outline: introduction general notes terms used for kabbalah the historical development of the kabbalah the early beginnings of mysticism and esotericism apocalyptic esotericism and merkabah… …
55Cave diving — is a type of technical diving in which specialized SCUBA equipment is used to enable the exploration of natural or artificial caves which are at least partially filled with water. It is an extension of the more common sport of caving, but is much …
56Operation Badr (1973) — Part of the Yom Kippur War/October War …
57Drilling rig — For a detailed diagram of a Petroleum drilling rig, see List of components of oil drilling rigs. Drilling rig preparing rock blasting …
58Asia — /ay zheuh, ay sheuh/, n. a continent bounded by Europe and the Arctic, Pacific, and Indian oceans. 2,896,700,000; ab. 16,000,000 sq. mi. (41,440,000 sq. km). * * * I Largest continent on Earth. It is bounded by the Arctic Ocean, the Pacific Ocean …
59international 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… …
60Battle of Passchendaele — For other uses, see Passchendaele (disambiguation). Battle of Passchendaele Third Battle of Ypres Part of the Western Front of the First World War …
