[AndrewC]

By finding fossils out of place -- a fossil rabbit in the pre-Cambrian, for example.[Previous post]

Actually, they can't. Evolution makes certain predictions (that fossils will be found in a specific sequence, for example).

How is that sequence determined?

[Junior]

By thousands of paleontologists working hand-in-hand with thousands of biologists, geologists and physicists, locating, dating and cataloging hundreds of thousands of fossils over a couple of centuries.