It's mostly hardpack sand with a few (only a few, it's not like Glamis at alll) deeper sandy areas. There is brush, river washes and fun hill climbs, I'd suggest picking up a map from the ranger station there and if you want to wander far enough from your camp area, a gps. No, I have never heard of anyone having issues w/ not having spark arrestors. It's a great place to go. Better check the weather reports though because it is super hot at this time of the year. Although, we did have this cool weather and lots of people dd head out for the long Memorial Day weekend.