Board Thread:Help Desk/@comment-23999285-20140311170652/@comment-24407447-20140915131757

Talk to the dryad, since she tells you how much of your world is hallowed/corrupted. If she says something like 7% hallow, 20% corruption, you may be in a rathe bad situation. Also, the V or X of hallow may have passed through too many non-hallowable blocks, such as snow or mud, and thus may not have hallowed enough blocks to spawn any shards. You may be screwed, sir.