Lightning can usually be observed in connection with ash plumes erupting from the island's volcanoes. Ash plumes and sulfur dioxide emissions recurred until January 2013. Additional material that might be found in these volcanic plumes include sodium, potassium, and chlorine. On 14 September 2010 white plumes were observed rising above the crater. These plumes can produce hotspots and flood basalts. The hats of the Australian Light Horse are decorated with emu feather plumes. The site's diversion tunnels frequently reached , enveloped in thick plumes of vehicle exhaust gases. The crests were usually made of plumes or horse hair. Since the 1990s, evidence has been found in favor of mantle plumes beneath the EAR. This flow is reflected in phenomena such as isostasy, post-glacial rebound and mantle plumes. The only other moon in the Solar System exhibiting water vapor plumes is Enceladus. Various lines of evidence have been cited in support of mantle plumes. Chromate is a significant component of many radioactive contaminant plumes. It is adorned with a pair of long black tail wires and large flank plumes. A carpet made of ostrich plumes.