Knowledge Skills

In relation to the note about using the knowledge skills for epic magic... how ARE these skills figured?

I went through several of my characters, and going by the numbers, I thought at first it was based purely on the lore skill + class factors, but the numbers aren't showing that, and I can't figure out any system that would cause the numbers I get.

Example, Alastair with maxed lore and a +7 int modifier has 57 knowledge(religion), 37 in the other three knowledges.... I would have thought that history would have been the greater, and if not history, arcana. Likewise, my epic druid has practically no nature knowledge (+2 on all the knowledge skills). Comparing between two of my clerics, one 40th level with 26 cleric levels, the other 24th pure cleric, same int mod on both, the 24th level character has higher scores than the 40th level character (who not only has more levels in total, but more cleric levels as well)