Lines 4-7 Summary

Line 4-5

And then — prodigious step

Around a Pile of Mountains —

• After its pit stop, the creature goes onward, to step effortlessly around mountains – not just one, but a "pile."
• Again, we wonder what this thing is; it's large enough to require tanks of food, and to skip lightly around mountain ranges. It's certainly no real animal…

Lines 6-7

And supercilious peer
In Shanties — by the sides of Roads —

• The creature "superciliously" (that is, haughtily or condescendingly) looks into the ramshackle buildings by the roadside.
• Notably, the speaker doesn't say anything about what it sees there. Why do you think that is?