Root problem, I am trying to fence in a small area in my backyard and there are allot of roots?

Question:post hole digger cannot get thru the roots any suggestions?

Answers:
You could cut the roots out with a reciprocating saw {sawzall) with a 12" blade. Push the blade into the dirt next to root and cut them out. I have done this with a fence, and with a big root lifting part of my sidewalk with success.