What text feature does the author use to highlight each section? numbers bold-face type roman numerals underlining

i think that will have something to do with the mississippi river but google will know the full answer for sure

one of the central themes of edward abbey's work has been his staunch opposition to the glen canyon dam on the colorado river that created lake powell, destroying stunning scenery and wildlife habitat, endangering many rare species of fish and animals, and also irreparably destroying many important archaeological sites which provided information about the early inhabitants of the united states.