At level 86, digging up a troll fragment gave me 38,170 XP. (level 14 guild). Solves gave nothing. That is .3% of a level per dig, roughly 1% of level per site.
I don't think the experience per dig has been adjusted. I was digging at 85 and 86 but was getting 17,350 (34,700 rested) per dig (104,100 (208,200 rested) xp per site with 6 digs in a site) on both levels (this was done without a guild, so no bonus xp).