Kat-
I kept walking past that carving as well!
What happened was basically the best of panhellism. During the 60s, membership was declining across the board and in order to increase membership there was talk of beginning a Panhellenic Council on campus. The members of AOII worked their butts of to get this formed and stabilized - at the cost of their own membership recruitment possibilities. At the end there were only two sisters remaining while the other chapters on campus flourished due to their efforts.
Okay, so that's the VERY brief version that I'm trying to dig from my memory of reading the chapter file in the archives at IHQ!
Hope that helps some!
Sarah