Dynamite stored in this little bunker was used to blast the area's first railway tunnel beginning in 1892. Built by Union Lumber Company, the tunnel runs through the ridge dividing the Pudding Creek and Noyo River watersheds. The men who worked with dynamite were called powder monkeys. Frequent contact with nitroglycerin, the explosive ingredient in dynamite, can cause neurological damage as well as other problems, and reportedly the powder monkeys became somewhat deranged and did not always exercise the best judgment despite working with high explosives.