Hi,

Well, the Somme played a role in the discussion whether Man met Mammoth. That discussion was about its gravel beds, IIRC, which would suggest there is indeed ground with stones there.

But the intended implication was, of course, that lyrics can have unlikely wording, but that that's not enough for a stamp of anachronism, as it then it comes down to proving negatives. How do you prove there was not a single location where soldiers slept where there were stones in the ground, not even stones that a farmer had put in at that spot to fill in a mud hole?

The anachronisms are the big things, the things that can't be reasoned away with a favourable interpretation of the lyrics.
"In the Year of the Lord seven hundred and six, we steamed up to the city of New York. Down below in the hold we had memory sticks, and some wine flasks with screw caps for corks."

Still probably plenty of anachronisms, even with that approach.

Bye,
                                                                Mysha