This is a whopping pile of creosote!!!  This is what came out of a clients fireplace flue.  Too much creosote build up can result in a chimney fire.  The NFPA (National Fire Protection Agency) recommends inspecting and sweeping a flue venting wood combustion after each cord of wood burned.  For other Top Hat Tips http://www.dmstorrschimney.com/our-soot-stories/top-hat-tips-feb-4-2011-10-42-02-pm-2