An good question, that I don't know the answer to. However, I'd assume (after seeing a video on the Stonewall Attack and the Dutch Defense (the Stonewall Variation) I would conclude that it is when you basically create a checker board with your pawns. In the diagram (as requested) The 5 forward pawns show this. Again, this is only an educated guess, if anyone knows for certain, I await your answer with anticipation.
Can anyone tell me what a "stonewall" is? (like Stonewall Dutch for example)
Diagrams would be apreciated.
Thanks!