Geologist time

2. Of a rock compared with others.
5. The age of a rock given as the number of years since the rock formed.
6. All the fossils that have been discovered and what scientists have learned from them.
8. The process of determining the age of an object using the half-life of one or more radioactive isotopes.
9. A group of similar organisms that can mate with each other and produce offspring that can also mate and reproduce.
12. This vast number of years into manageable periods, scientist created the geologic time scale.

1. Long span of time which begins geologic time.
3. The preserved remains or traces of an organism that lived in the past.
4. To improve something by making small changes.
7. One of the three long units of geologist time between the Precambrian at the present.
10. A horizontal row of element in the periodic table.
11. A record of the geologic events and life forms in Earth’s history.