Radiometric dating human history
It looks like this: Most of the other measurements for the age of the Earth rest upon calculating an age for the solar system by dating objects which are expected to have formed with the planets but are not geologically active (and therefore cannot erase evidence of their formation), such as meteorites.
Below is a table of radiometric ages derived from groups of meteorites: As shown in the table, there is excellent agreement on about 4.5 billion years, between several meteorites and by several different dating methods.
While these values do not compute an age for the Earth, they do establish a lower limit (the Earth must be at least as old as any formation on it).
This lower limit is at least concordant with the independently derived figure of 4.55 billion years for the Earth's actual age.
The actual underlying assumption is that, if those requirements have not been met, there is no reason for the data points to fall on a line.
The resulting plot has data points for each of five meteorites that contain varying levels of uranium, a single data point for all meteorites that do not, and one (solid circle) data point for modern terrestrial sediments.
And from the slope of the line we can compute the amount of time which has passed since the pool of matter became separated into individual objects.
See the Isochron Dating FAQ or Faure (1986, chapter 18) for technical detail.
This value is derived from several different lines of evidence.
Further, the processes of erosion and crustal recycling have apparently destroyed all of the earliest surface.