According to the South China Morning Post, "More than 400 fragments of stone implements have been found in a stratum of sediment that was originally thought to have formed 15 million years ago". The site was in northern China, in Shibaozhuang village.
At the time of the find (in 2013), and according to evolutionary dating methods and assumptions, the earliest tools appeared in Africa no earlier than 2.6 million years ago. So, according to a researcher: "The sediment [in Shibaozhuang] must be considerably younger than geologists thought, because no stone tools could have appeared so early."
Hence, despite it being said that the sediments had "long been determined by geologists to be at least 15 million years old" they now suddenly 'must' be much younger, as such an old date would be incompatible with evolutionary ideas of human origins.
Whilst any date of millions of years does not fit the framework of biblical creation, the above demonstrates how evolutionists confine dates to within 'acceptable' limits of their theory. i.e., the sediments can't be that old because that goes against evolutionary theory. Later, when a younger date is presumably 'found', this date can then be used to support evolutionary theory. And the whole episode may be used even as an example of how 'science' is self-correcting.
This is a great example of how, when the evidence contradicts evolution, it is the evidence that gets thrown out, not evolutionary theory.
Chen, S., Sediment in Nihewan might hold clues to the first Homo sapiens, www.scmp.com, 5 November 2013.