I don't think it is memory related because I have had it happen just shortly after login as well but always after i used a shrine to go somewhere. I also have 16GB of memory plus 4GB on the card. It usually corrects after zoning as well.
Hoping that by showing them what we are talking about rather than just posting a description it will give them a better idea of what we are talking about and how to fix it. It's a bit of an odd thing cause it doesn't follow the ground texture mapping level.
I suspect it's a VRAM or loading thing. It usually crops up in areas where there's a ton of players gathered, like outside an Undaunted Enclave or in the middle of a huge group in Cyrodiil.
Nothing's necessarily wrong with your system, it just needs time to catch up and load properly. Normally when I see this ground thing it can't even be walked on because it's still loading, though in that case it tends to resolve quickly.
Happens to me in many games, online and off. It's a texture bug, loading mipmaps instead of the full resolution. Like MIssBizz said though, relog or just move to another area.