geology : a scientific theory that the Earth's surface is made of very large sections that move very slowly; also : the movements of the large sections that form the ...
(used with a sing. verb) A theory that explains the global distribution of geological phenomena such as seismicity, volcanism, continental drift, and mountain ...
Mar 21, 2016
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A Aa - Aa (pronounced "ah-ah" - a Hawaiian term), is lava that has a rough, jagged, spiny, and generally clinkery surface. In thick aa flows, the rubbly surface of ...