Going to go out on a limb here as I have spent a long time searching for this film and am beginning to forget the details but here goes.

The film is a fantasy / supernatural horror genre film set in america and would have originally been produced in the mid 80's (maybe)

I can remember a few details like this college student finds a girl in some excavation and she is entangled in a tree and he sets her free but when he does he release some evil spirit that is part of her that chases them about.

I think the girls name was Elida or something sounding like that, the final bit i remember is that they end up going into a library or something and thats about it.

A long shot I know but maybe it may ring a bell.

Ed

Sounds vaguely familiar. Did the tree trunk kind of open up? Something about some bloke dying and the girl/women hiding in the tree from whoever killed him?

To be honest not sure, was that long ago i can barely remember those details in OP, I'm sure trying top remember the name of this film will continue to haunt me for more time to come :)