Magnetic striping of the oceans, and the lengthier ice cores should do it.
A good additional one will be the Gaia spacecraft launching this year, which will be able to measure the distance to stars up to 30,000 light-years away through straightforward parallax trigonometry, thus adding yet another proof the galaxy, at least, is older than 6,000 years.
It will be amusing to watch the young-earth creationists contort themselves into trying to disprove those results - probably through some silly claims the speed of light has radically changed in the last 6,000 years.
No where in the bible does it say the earth is 6,000 years old.
That’s just a liberal talking point to try to discredit Christianity.