Well, my foot decided to do a bit of seeping so I now have some sample real stuff on white paper. I've never really studied this but the bright red turned brown within a half hour or so... brown it is.
So I had a look on the web and found this site which kinda ticks that box and several others. I'm bookmarking this one!
Dried blood is in there.
Thanks tilt, yes it is a tad "draughty" on the map and that's exactly the kind of comment on the grid that I need! The soil texture will be refined - I want to put cart tracks in the "mud" itself by modifying the height field and I needed to get my cart design partly done to get the wheel tracking width right.
This is one cart "in the workshop" at the moment. I'm thinking of having two. One "hardtop" and one "soft-top". One will have to have the obligatory broken axle so you get some sort of view of the side from the overhead view. (The cliché-grinder is grinding!). Given time I'll put some markings on the hard-top which could be a clue about the Tin Man aswell.
If anyone is wondering - the carts got left behind by our original attackers because they won't fit through the trees - they took most of the "goodies" and livestock though...