kd7sov | I hate coming up with titles/names

I'm considering a set of fanarts emphasizing each of the classic elements, and particularly the centrism thereof. I started with "core of earth", "soul of fire", and "heart of water", but couldn't come up with any synonym I liked for air. After some thought - and some ultimately unhelpful perusing of a thesaurus - it occurred to me that I could do "soul of air" if I switched "core" to fire. This necessitates a replacement for earth, which brings me to this post.

Do you think "pillar of earth" would work, or is that too close to the imagery of Lot's wife?