According to Catskill forest historian Michael Kudish, the Slide wilderness contains the most extensive tract of first-growth forest in the Catskills. Much of the area remained out of reach during the peak years of logging and barkpeeling from eastern hemlock trees, to make tannin for leather production in the mid-19th century, and thus remained largely untouched. Indeed, the upper valley of the East Branch of the Neversink, located centrally within the SMWA, is the only completely wild valley in the Catskills. It is possible to look out over it from several points on the surrounding mountains and see no evidence of civilization.