English: Glowing `a`a lava flow front advancing over pahoehoe lava on the coastal plain of Kilauea Volcano, Hawaii. '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.
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2006-10-23 15:45 Edwardtbabinski 800×500×8 (89587 bytes) Source United States Government http://volcanoes.usgs.gov/Imgs/Jpg/Photoglossary/aa_large.jpg In difference to pāhoehoe, Aa is a term of Polynesian origin, pronounced Ah-ah, rough, jagged, spiny lava.
{{Information |Description=[http://volcanoes.usgs.gov/Products/Pglossary/aa.html] This is what is now lava. It used to be what was called magma. Magma is a hot substance that is deep with in the earth. Volcanoes grow just like humans do. They can grow up