GEOL 1250 Midterm: Midterm 2 - Review Questions

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Is indicated by the types of index minerals present in the rock a: reflects the pressure and temperature conditions at which the rock is formed. If the half life of a radioactive parent isotope is 1. 5 million years (ma), and a rock has. 25% parent and 75% daughter, the age of the rock is. Is constant and characteristic of each isotope: a clastic sedimentary rock contains grains of the mineral feldspar that have an age of. The sedimentary rock is cut by two igneous dikes, one of them has an age of. 396 ma and the other once an age of 68 ma. What is a possible age of the sedimentary rock: 410 ma. The arete of radioactie decay for a given isotope is constant. The earth must be at least several hundren million tears old. Geological processes in the past were the same as those that we see today.