The band at the equator of Auolun. Every 50 years, in the Spring and Fall Solstice, the gaseous cloud that wreathes Auolun acts similar to a magnifying glass and the temperatures on Auolun become so intense that the ground itself ignites (this phenomina is known as the Firewall) . When the Solstice ends, the ground takes a whole year to cool, leaving a band of obsidian that spans the entire equator. It is speculated that this has been happening for forever … and ancient texts seem to support that. Dwarven inspections of the Obsidian band show that Band goes down a mile and a half and stops abruptly. Thousands of miles to the south however, it is rumored that the Band continues plunging to the center of the earth.
In the Elven tongue, it is called Earlo Mornakhelek (The Sea of Black Glass), and the Gnomes call it Dorraghys Folmylaan (The Dark Flatlands). The Dwarves call it Gomyrgless Moger (or Blackglass Wall).