The earth is irrefutably older than 10 000 years. There are literally mountains (excuse the pun) of evidence which show the earth to be incredibly old (approx 4.4 - 4.5 billion years old).
There are many points that the young earth creationists bring up to refute modern scientific geology. One that stood out for me was how they described the formation of the grand canyon.
The grand canyon's highest point from sea level (the tops of the gorges) is somewhere in its centre. How then did the Colorado river flow over this centre high point to erode the canyon? did the water flow uphill and then down hill to the sea?
This is the type of idiocy that the young earth creationists come up with as arguments against geology. They didnt take into account that there was crustal uplift in the centre of the canyon at the ending stages of its formation. That is why its central region is at a higher elevation than the Colorado river's source. If they knew anything about geology, they would see that crustal uplift is very common.
It is their simple to non-existent knowledge of geology that allows them and others to believe the silly theories which are built to refute sound peer-reviewed modern scientific geology