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a device for capturing wild animals and birds. There are traps that require the attendance of a person and there are those that are actuated by a trigger mechanism (unattended traps). The first group includes various types of nets for capturing the animals live. The second group comprises three types of traps: those that crush, those that grasp, and those that capture live.
There are three kinds of traps (deadfalls) that crush the animal. One is used in the tundra to capture arctic foxes and, more rarely, other animals. It consists of a floor, two walls, and a weight held by a trigger mechanism. The other two operate on the same principles; one of them is used for capturing both small (squirrel, sable) and large (wolf, bear) animals, while the other is used only for small animals (squirrel, sable, Siberian weasel, polecat).
There are three kinds of traps that grasp the animal. One is the steel-jaw trap (seeSPRING TRAP). The second is the noose, which is set across game trails or at den openings to capture rabbits, small rodents, and game birds. The noose entraps the animal and is tightened by the animal’s movements. The third type operates with the aid of a taut crossbow, whose force presses the animal against the trap’s crosspiece.
There are a number of traps for capturing animals live. The box-type trap is one. It is of various sizes and designs and is used for capturing many economically important animals, such as muskrat, coypu, and mink. Rabbit warrens and pitfalls are sometimes used in hunting regions to capture capercailles, grouses, and partridges.
Many traps that were used in prerevolutionary Russia have been banned because they led to the killing of a great number of animals and in some cases proved to be dangerous to humans.
REFERENCERakhmanin, G. E. Tekhnika dobychi promyslovykh zhivotnykh samolovami. Moscow, 1951.
S. A. LARIN
(also traprock), the group designation of basic igneous rocks with a characteristic stair-step jointing.
Traps include such rocks as diorite, gabbro-diorite, gabbro, dolerite, and basalts and occupy considerable areas called trap regions. Traps consist of clinopyroxene (usually augite), olivine, basic plagioclase, magnetite, apatite, and, less frequently, ortho-pyroxene and biotite. Among the many secondary minerals are iddingsite (which develops by alteration of olivine), palagonite, chlorite, zeolites, prehnite, and actinolite. An ophitic texture is characteristic of traps; a microlitic or glassy texture is less common. Traps are usually gently sloping lava flows, sometimes with a pillow structure, tuff beds, or intrusive veins 10–25 m thick. Dikes, bosses, ring dikes, and necks are also encountered.
Traps are typical of craton regions of the earth’s crust and may occupy considerable areas. They are found, for example, in Eastern Siberia (about 2 million sq km), in the Deccan plateau of India, in South Africa, and in the Paraná plateau of South America. Traps are mostly derivatives of tholeiitic magma (see) and partly of olivine-basalt magma; they apparently originated in the mantle. In the Central Siberian Plateau the traps were formed by the intrusion and extrusion of magma that occurred in several phases over a long period of time, from the Permian to the middle Triassic. The thickness of the traps may reach 2,000 m.
Traps include many kinds of useful minerals. The differentiation of the magma forming the traps led to the development of copper and nickel sulfide deposits (as in the Noril’sk Ore Region), platinum ore deposits (as in South Africa), and iron ore deposits. Deposits of Iceland spar are associated with the products of postmagmatic hydrothermal processes. Deposits of graphite that developed during contact metamorphism of coals under the action of traps are temporally correlated with formation of the trap.
REFERENCESGodlevskii, M. N. Trappy i rudonosnye intruzii Noril’skogo raiona. Moscow, 1959.
Zolotukhin, V. V. Osnovnye zakonomernosti prototektoniki i vo-prosy formirovaniia rudonosnykh trappovykh intruzii (na primere Noril’ska). Moscow, 1964.
V. P. PETROV
This term is associated with assembler programming ("interrupt" or "exception" is more common among HLL programmers) and appears to be fading into history among programmers as the role of assembler continues to shrink. However, it is still important to computer architects and systems hackers (see system, sense 1), who use it to distinguish deterministically repeatable exceptions from timing-dependent ones (such as I/O interrupts).