Martin; S. There are three types of radioactive decay that can occur depending on the radioisotope involved: However, they do not reveal the relative ages of rocks preserved in two different areas. Plant Biology 1. Accordingly, the oldest rocks in a sequence are at the bottom and the youngest rocks are at the top. While uranium is water-soluble, thorium and protactinium are not, and so they are selectively precipitated into ocean-floor sedimentsfrom which their ratios are measured.
Dating Rocks and Fossils Using Geologic Methods
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See also: Dating method that uses heat to measure the amount of radioactivity accumulated by a rock or stone tool since it was last heated. Relative Dating with Fossils: