Here are some initial concept sketches for the cover of a 1984 science fiction novel called Digging Leviathan by James Blaylock.
The sketches are drawn in pen and marker. I was trying to stay loose, letting ideas happen with each iteration, like a musician's multiple takes in a recording studio.
In the story, the hero makes a machine that can dig under modern-day Los Angeles in search of Pellucidar.
Blaylock is widely regarded as one of the originators of the steampunk movement. I loved the way he introduced fantastical elements into the banal reality of the modern world.
See an unused color sketch for this cover at the previous post, "Digging Machine"