Geologic Time Table
30-Aug-94 23:46:23
Sb: #143925-Geologic Time Table
Fm: Lanny R. Ream 73512,1163
To: Kamron Kirkconnell 73740,2246
You might say all matter on earth is the same age (as the molecules or
molecular parts), but the crystals, grains, etc. that make up rock are of
different ages, i.e. when a lava flow is formed it takes on a certain ration of
minerals, and thus elements and many of these are unstable and break down at
certain rates (such as Uranium breaking down to Lead and all those nasty
radiocative things, and many other elements do the same thing). Because of
this, it is possible to measure the ratios of isotopes of U, Pb to each other,
Potassium to Argon, etc. to determine the ages of rocks. Thus, the igneous
rocks can all be dated because they formed by the each mineral crystallizing
out of a melt of some sort and have a determined ratio of one element to
another at the time of formation. Measure the amount of change and you can
determine the age.