1.   Each of these incremental shifts represents only a brief moment in geological time.

2.   Every radioactive isotope provides an independent clock for measuring geological time.

3.   Over geological time it is likely that impacts have reduced the mass of the Martian atmosphere by a factor of one hundred.

4.   What we do know is that geological time is awfully long.

5.   Biological evolution works on a nearly geological time scale, which suggests that human nature, as a partial product of our genes, is basically constant.

6.   Fortey ends with some reflections on the measurement of geological time.

7.   If microbes are discovered in the heated zone, that will suggest that they migrated there relatively recently in geological time.

8.   It would take very convincing data coming from many different directions, but the mechanisms used to measure geological time are not unshakable truths.

9.   Over geological time, nature has conspired powerfully against what would become China.

10.   Over geological time, underground streams carved caves.