I just read the Prelude again and this is what Kalak says:
"The plain was a place of misshapen rock and stone, natural pillars rising around him, bodies littering the ground. Few plants lived here. The stone ridges and mounds bore numerous scars. Some where shattered, blasted out sections where Surgebingers had fought. Less frequently, he passed cracked, oddly shaped hollows where thunderclasts had ripped themselves free of stone to join the fray."
It just sounds like the plain. I know I'm on shaky ground here but it always seemed to me that the plains were the ultimate battlefield.