As for the screenshots, I'm none too good at working with graphic files, so sorry that they're quite big (physical size - I have enough sense to save them as jpegs!
I tried to make sure this bug hasn't been reported already. If it has I apologize, and feel kinda stupid!
If it hasn't, quite frankly I'd be suprised that no one else has run into this before... 
So far, this has happened to me in every game that I've explored to the edge of the mini map prior to the map being "centered" from a tech advance. I'm not sure, but I think that has a factor in it. I'm going to test that out next...
At any rate, take a look at the following screenshots.
Fog of War Glitch 1 (FWG1) shows an active warrior approaching the edge of my island.
FWG2 shows what happened when I scrolled the screen to the left just slightly.
FWG3 shows a shot just south of that area.
FWG4 is at the northern edge of the map along the same line. Note the black Ice Caps.
In FWG5 the active unit is the galley on the left.
Note the black trees and overly-bright land areas.
FWG6 is a result of scrolling the map just to the left. That reveals the area around the galley as it should be. But obviously, the FoW is still messed up.
Looking at this series of screenshots you can see that there's a relationship between the edge of the mini map and what is displayed regardless of whether the map is "centered" or not.
Take a look at the difference in the mini maps between FWG2 & 3. In the early game, prior to the world map being "centered", (in FWG2) my warrior had reached what will later be the western edge of the map - that line being revealed as the "glitch" in the FoW. Then when the world map is centered, as in FWG3, that line in the FoW becomes the edge of the map.
Obviously, in FWG 2 & 3 the areas on the left of the line were as yet undiscovered/unexplored, so they should naturally be black.
I'd really like to know if anyone else has run into this also.
This is kinda major in my eyes and I'm surprized a) I haven't seen any mention of it, and b) it hasn't been fixed in the 1.09 patch.
I'm running the game on two entirely different computers, one a quite capable desktop with loads of RAM, and CPU and GPU (nVidia) power. The other a less (but sufficiently) capable laptop with a Radeon graphics card. In fact I can put a saved game from one an fire it up on the other and I get the same results!
kroYM
I tried to make sure this bug hasn't been reported already. If it has I apologize, and feel kinda stupid!


So far, this has happened to me in every game that I've explored to the edge of the mini map prior to the map being "centered" from a tech advance. I'm not sure, but I think that has a factor in it. I'm going to test that out next...
At any rate, take a look at the following screenshots.
Fog of War Glitch 1 (FWG1) shows an active warrior approaching the edge of my island.
FWG2 shows what happened when I scrolled the screen to the left just slightly.
FWG3 shows a shot just south of that area.
FWG4 is at the northern edge of the map along the same line. Note the black Ice Caps.
In FWG5 the active unit is the galley on the left.

FWG6 is a result of scrolling the map just to the left. That reveals the area around the galley as it should be. But obviously, the FoW is still messed up.
Looking at this series of screenshots you can see that there's a relationship between the edge of the mini map and what is displayed regardless of whether the map is "centered" or not.
Take a look at the difference in the mini maps between FWG2 & 3. In the early game, prior to the world map being "centered", (in FWG2) my warrior had reached what will later be the western edge of the map - that line being revealed as the "glitch" in the FoW. Then when the world map is centered, as in FWG3, that line in the FoW becomes the edge of the map.
Obviously, in FWG 2 & 3 the areas on the left of the line were as yet undiscovered/unexplored, so they should naturally be black.
I'd really like to know if anyone else has run into this also.
This is kinda major in my eyes and I'm surprized a) I haven't seen any mention of it, and b) it hasn't been fixed in the 1.09 patch.
I'm running the game on two entirely different computers, one a quite capable desktop with loads of RAM, and CPU and GPU (nVidia) power. The other a less (but sufficiently) capable laptop with a Radeon graphics card. In fact I can put a saved game from one an fire it up on the other and I get the same results!

kroYM