The zoo train at Henry Vilas is a tiny thing intended for parents and toddlers. It makes a short round trip, passing through an artificial stone tunnel that doubles as its garage at night.

The Zoo director at the time, Jim Hubing, asked me to decorate the interior’s smooth but irregular stone walls with scary images. We decided the unifying theme would be that of an abandoned mine with dark transverse passages containing all sort of dangerous critters and feature a wealth of multi-colored gem stones (from a local hobby shop) popping out of the walls.

Sitting on a rock ledge near the exit I put an old wooden ammunition box left over from my Marine Corps days but relabeled as dynamite.

On top of the box sits a bundle of red sticks with the fuse dangling dangerously close to an electric candle.

The exterior of the train tunnel, done in 2004, was even more fun. Jim wanted something painted on the sedimentary layers of rock along one side of the tunnel facing a heavily trafficked walkway. Having been infected by Mad Magazine as a boy, I immediately thought of gag images: ancient petroglyphs, but humorous ones, of some ancient hunting-gathering culture doing stupid things.

Jim went for the idea. See if you can interpret the enigmatic meanings.

Not many passersby seem to take much notice of the pseudo-ancient images, but once a person notices the goofiness of one, he or she quickly engages the rest of their party, as well as passing strangers, into discovering all the gags running along the rockwork. I wish I had video of the phenomenon; it was very gratifying.

What do they mean?