I am currently reacquainting myself with the Oracle documentation, starting with the Concepts Manual, now on Database Administration, and on to a load more. It's surprising what one can forget, or think one knows, but doesn't.
Anyway, I was surprised to find that there is a nice little tool - written 11 years ago - called DEPTREE.
The doco is here.
NOTE: the objects created by utldtree.sql are created in the schema you are current logged in to.