They all seem to be different, like I've personally seen gravel under fabric under wood chips I've seen the actual ground under the fabric under wood chips, I pulled a relic out of the ground under the fabric, some horse tack I've seen just sand, tons of sand Would t be surprised if they had sand under wood chips, though the deus isn't too horrible in dry sand, I find it's the wet sand by the water it goes really haywire
try to turn on beach on the selection on the ground ballance where it lets u slect manual gb or pumping gb or beach ground ballance i had this issue at a park it helped