Thanks all.

@SplinterGroup  Yes it is black epoxy.  Your concern about further splitting is valid.  I noticed the other day that a pretty good sized split has appeared on one edge of the epoxy/wood boundary on the bottom shelf.  I will have to pour some more epoxy, but will wait another year to do it to let the piece dry some more.  I probably should have put a dutchman (bow tie) to span the gap, but I am pretty sure that would have just forced a crack to appear in another spot.  I should have waited for a few more years for it to properly dry, but just did not have the room to store it, and could not leave it outside or the bugs would feast.