Radiometric dating sediments
As it turns out, the Moon is truly a whole new world, with rocks and surface features that provide a record of events that occurred during the first billion years of the solar system.
This record is not preserved on Earth because all rocks formed during the first 800 million years of Earth's history were recycled back into the interior.
So, some caution might be in order before even long established theories are accepted as the "gospel truth", especially when some of the most famous scientists in the field start to question their own life's work.
In considering the theory of human evolution it is interesting to note that some very well known scientists have actually suggested that the line of human evolution is far from clear.
Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves.
By measuring the amount of radioactive decay of a radioactive isotope with a known half-life, geologists can establish the absolute age of the parent material.
A number of radioactive isotopes are used for this purpose, and depending on the rate of decay, are used for dating different geological periods.
More slowly decaying isotopes are useful for longer periods of time, but less accurate in absolute years.
Biostratigraphy does not directly provide an absolute age determination of a rock, but merely places it within an interval of time at which that fossil assemblage is known to have coexisted.
Both disciplines work together hand in hand however, to the point where they share the same system of naming rock layers and the time spans utilized to classify layers within a stratum.