Relative dating does not provide actual numerical dates for the rocks.
Dirty chat hook up - Dating of rock layers
Geologists have studied the order in which fossils appeared and disappeared through time and rocks. Fossils can help to match rocks of the same age, even when you find those rocks a long way apart.
This matching process is called correlation, which has been an important process in constructing geological timescales.
This time interval was from 542-520 million years ago.
This approach avoids the circularity associated with using fossils to correlate rocks, and then using those correlations to infer biological patterns…” (“Cambrian Explosion: New Timeline for Appearances of Skeletal Animals in Fossil Record,” , Nov.
(Welles, Samuel Paul, “Paleontology,” In some cases darwinists have recognized circularity as a typical problem in evolutionary models and worked to avoid it.