Unlisted Terrain

[Tadaas]

Isn't there an unlisted terrain?
I have seen workers getting 1 food from a snow covered tile. This does not fit any terrain definition. I also see no building to improve it. I have seen 2 hammers from a snow covered forest so this is a normal forest.
I have seen a grassland with snow on it but do not know if this tile provides 1 or 2 food? Anyone know?

 

[shadowplay]

I think they count as plains.

 

[InFeRnOgTiTaN]

Sort of in the same topic - I wish the magnifying glass showed you what the tile was at any time - would help in planning where to settle before you actually get a settler and can see the tiles with the magnifying glass that way.