You can see a minimap on the Touch Screen when you watch the video of the Day Of Lavos, and when you actually witness Lavos' eruption (has to be when you travel to 1999 A.D. since the Black Omen is in Antiquity (Dark Ages) when it goes down, no matter which time period you're in. I guess they just didn't want to show Lavos erupting in any other time than in Antiquity when the Black Omen falls.