Rocky, obvs.

CHIrock or CHI (shy) stone

Bouldery McBoulderface.

“Deep Crust” surely?

Rocky McRockFace

Bean

Peewee Pebblestone

As an Australian aware of Chicago's Irish heritage and the implied weight balancing our antipodean clime, I'd suggest "Tip O'Dea".

PS. If visiting Chicago check out the Lincoln Park Conservatory, an amazing historic plant collection with one of the world's best ferneries, very close to downtown. https://www.lincolnparkconservancy.org/projects/conservatory...

Big Boy Boulder

Stonehangar, of course