Externet Posted October 7, 2011 Posted October 7, 2011 Hi. About the age of certain rocks... If a rock is -say 1 million year old- What was the material/mineral/compound it is made of 1.1 million years ago (or before such date) ?
Realitycheck Posted October 7, 2011 Posted October 7, 2011 Depends on what type of rock it was. Igneous rocks were lava and the sort. Sedimentary rocks were trees, soil, anything that settled into the earth. Metamorphic rocks were one type of rock, like sedimentary, that got transformed by heat and pressure, into a different rock.
Moontanman Posted October 8, 2011 Posted October 8, 2011 (edited) Hi. About the age of certain rocks... If a rock is -say 1 million year old- What was the material/mineral/compound it is made of 1.1 million years ago (or before such date) ? The age of a rock is usually judged by the time it became a rock, in lava it's when it cooled, in sedentary rock both the rock strata and the individual grains it's made of can often be dated but not always. Sometimes it's the relative age of layers of rock that are dated, when a rock is changed as in metamorphic rock it's the change that sets the dating mechanism. Sometimes several different methods are used to judge the age of rocks. So it usually depends on the type of rock as to the dating method. Edited October 8, 2011 by Moontanman
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