A method for identifying and measuring the chemical elements in a sample to be analyzed. The sample is first made radioactive by bombardment with neutrons, charged particles, or other nuclear radiation. The newly radioactive atoms in the sample give off characteristic nuclear radiations that can identify the atoms and indicate their quantity.

    `A`a flow `A`a (pronounced "ah-ah") is a Hawaiian term for lava flows that have a rough rubbly surface composed of broken lava blocks called clinkers. The incredibly spiny surface of a solidified `a`a flow makes walking very difficult and slow. The clinkery surface actually covers a massive dense core, which is the most active part of the flow. As pasty lava in the core travels downslope, the clinkers are carried along at the surface. At the leading edge of an `a`a flow, however, these cooled fragments tumble down the steep front and are buried by the advancing flow. This produces a layer of lava fragments both at the bottom and top of an `a`a flow.

    Atomic Absorption Spectrometry for chemical analysis especially at low levels.

    Surface removal of ice or snow from a glacier or snowfield by melting, sublimation, and/or calving.

    Physical wearing and grinding of a surface through friction and impact by material carried in air, water, or ice.

    The mechanical wearing or grinding away of rock surfaces by the friction and impact of rock particles transported by wind, ice, waves, running water, or gravity. Reference : R.L. Bates & J.A.Jackson, DICTIONARY OF GEOLOGICAL TERMS, Third Edition, American Geological Institute, 1983

    The grinding and scraping of a rock surface by the friction and impact of rock particles carried by water, wind, and ice. Reference : Tarbouk, E.J. & F.K. Lutgens, (2006), EARTH, 8th edition, Pearson Education International.

    The content of water vapor in air, expressed as the mass of water per unit volume of air. Reference : R.L. Bates & J.A.Jackson, DICTIONARY OF GEOLOGICAL TERMS, Third Edition, American Geological Institute, 1983

    absolute humidity The mass of water vapor in a given volume of air. It represents the density of water vapor in the air.

    The ability of a rock to conduct a fluid, e.g. gas, at 100% saturation with that fluid. Reference: R.L. Bates & J.A.Jackson, DICTIONARY OF GEOLOGICAL TERMS, Third Edition, American Geological Institute, 1983.