Explore the nature of time in A Brief Overview of Time
Carbon dating depends upon carbon in the atmosphere and can be used only for dating once-living material.
Lake varves record annual layers.
The Cesium atomic clock is the U.S. time standard.
Cepheid Variables as Yardsticks and Clocks
Type 1a Supernovae give a measure of distance and time.
Nuclei as Clocks measure vast time periods.
Alpha decay halflives cover over 20 orders of magnitude and confirm their dependence on the fundamental constants c and h.
The whole-rock isochrons are methods to read the clocks-in-the-rocks
The measurement of moon rocks from the Apollo missions gave information consistent with meteorite measurements.