It appears from the statement of this verse (SB 6.12.26) that sometimes there are flying mountains and that their wings are cut by the thunderbolt of Indra. Vrtrasura's huge body resembled such a mountain: Revision history
Diff selection: Mark the radio buttons of the revisions to compare and hit enter or the button at the bottom.
Legend: (cur) = difference with latest revision, (prev) = difference with preceding revision, m = minor edit.