Graphical glitch in Lion's Arch
I just went here to look at this after reading your post.
The same thing happens for me. Depending on how close you are to the area of ground, the camera angles that cause it alter a bit, but it will consistently color brown as your angle stays mostly east/southeast of it (i.e. more or less if your camera is pointed toward that area from the direction of the two huntsman stations or the charr NPC between them).