Lack of 50:50 racemization (Racemization dating is a process which uses the measurement of the decay rate of carbon protein amino acids to date once-living organic tissue)
of amino acids in fossils “dated” at millions of years old, whereas complete racemization would occur in thousands of years.

Read more here.

Science is based on observation, and the only reliable means of telling the age of anything is by the testimony of a reliable witness who observed the events. The Bible claims to be the communication of the only One who witnessed the events of Creation: the Creator himself. As such, the Bible is the only reliable means of knowing the age of the earth and the cosmos. In the end we believe that the Bible will stand vindicated and those who deny its testimony will be confounded.

Source: Creation.com