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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Title Description
 Unconsolidated Surface Deposits   

Surface deposits such as moss, peat, sand, gravel, silt, or mud.  
 Hydrothermal Stage   

That stage in the cooling of a magma during which the residual fluid is strongly enriched in water and other volatiles. The exact limits of the stage are variously defined by different authors, in terms of phase assemblage, temperature, composition, and/or vapor pressure; most definitions consider it as the last stage of igneous activity, coming at a later time, and hence at a lower temperature, than the pegmatitic stage. 
 Jig Bed   

The agent used in a jig that consists of the heavy fractions in the coal that behave in some respects like a dense fluid. The pulsation of the water or the motion of the screen keeps the bed open or in suspension during part of the cycle so that heavy minerals entering the jig can settle into the bed. Lighter materials cannot penetrate the jig bed and therefore are forced to remain in the upper part of the jig and eventually discharge over the top. Other agents in use are lead shot, iron punchings, iron shot, pyrite, and magnetite. 
 Tectonic Creep   

The almost constant movement of certain fault blocks that allows strain energy to be released without major earthquakes. 
 Valence   

The degree of combining power of an element or a radical.  
 Wire-line Drilling   

The drilling of boreholes with wire-line core-barrel drill-string equipment. 
 Ultimate Tensile Stress   

The load at which a test piece breaks, divided by its original area.  
 Natural Slope   

The maximum angle at which loose material in a bank or spoil heap will stand without slipping. 
 Sedimentology   

The scientific study of sedimentary rocks and of the processes by which they were formed; the description, classification, origin, and interpretation of sediments. 
 Jurassic   

The second period of the Mesozoic Era (after the Triassic and before the Cretaceous), thought to have covered the span of time between 190 million years and 135 million years ago; also, the corresponding system of rocks. It is named after the Jura Mountains between France and Switzerland, in which rocks of this age were first studied. 
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