Crazyzeke.
First of all, welcome to simviation.
What you are describing is not a problem with "terrain" but a problem with missing "textures". Terrain is used to represent hills valleys, cliffs and mountains etc. in other words the ups and downs

. Textures are what are used to "paint" the areas we see with detail.
Have you installed any new scenery recently?
I'm sure wiser heads than mine are going to be able to help with this problem .
In the mean time, all the best.
Zaphod.
What doesn't kill you makes you stronger. But why take the risk?
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