The portal explosion from the Ashfall caused a leyline running through Amaril to explode, ripping a gash through the continent. The Western two-thirds of the continent is now called Antonica, while the Eastern third of the land mass is still referred to as Amaril.
The gash flooded during the period following the Ashfall, leaving a relatively narrow and easily crossed river. The geological instability continued for decades after the Ashfall, causing the channel to grow wider as land crumbled into the waterway. By the Age of Heroes, the strait has become wide and treacherous.