In 2009, Australian creationist Dr. Don Batten, “Ph.D. in Plant Science,” wrote a compendium of evidence for a young earth, “101 evidences for a young age of the earth and the universe” for Creation Ministries International.
RationalWiki has just published a point-by-point refutation of each of these arguments (some of which are truly moronic) in their new article with the same title as Batten’s. (I’d suggest they add the word “rebuttal” to their title!). I’m pointing out their piece here for two reasons: so you can have a convenient place to go if, God help you, you need to refute a young-earth creationist; but also because they’re seeking input from readers. If you find any mistakes or unclear issues in their piece, post it as a comment below.
If you’ve dealt with creationists, you’ll be familiar with some of these arguments, but it’s nice to see them dealt with in one place.
Note that RationalWiki also has another article that’s partly but not completely overlapping, “Evidence against a recent creation.” You might want to have a look to see just what kind of arguments this extra-loony brand of creationism employs