A boarding barn near me, has clay footing underneath the sand, and it's really not good.
The sand gives to easily. So, when it rains, and if you go out to ride, the sand will be dry and safe, but the clay will still be wet, so it forms big deep hoofprints. Several horses have mistepped and gone completely down, stepping into one of those prints. You can't see them at all because of the sand, and it's really quite dangerous.
Sand, I really don't like either, since you loose all of it too quickly, and it's absrasive.
"You're just as sane as I am."~Luna Lovegood.