Strange Lines in Scenery

Can anyone tell me what causes these weird lines in the scenery? This is with the Alaska Mesh DL from Marketplace, but it is not a new phenomenon.

 

(Not the squiggle. The blue/white line.)

 

Is there a fix?

 

 

A enormous, vast, immense, very large, very big, great, massive, cosmic, colossal, prodigious, gigantic, gargantuan, mammoth, monumental, tremendous, stupendous, giant, towering, hefty, bulky, weighty, heavy, gross, monstrous, elephantine, mountainous, titanic, epic, Herculean, Brobdingnagian, princely, generous, handsome, jumbo, mega, monster, whopping, whopping great, thumping, thumping great, humongous, hulking, bumper, almighty, astronomical, astronomic, whacking, whacking great, ginormous cloud shadow?

Edge of a mesh boundary, can be quite visible in certain circumstances unfortunately and may also be affected by your LOD settings, although I'm no expert on that.

I'm not so sure about mesh, which only affects topography, not the colours of the landscape.

It's the dividing line between two satellite images which were taken at different times of day/month/year, and you can find examples of these all over the world.