I was going to lead my girl across it the first time, but even with that I'm wondering if it's a good idea. Some of the rocks have "river green" on them. If I walk across barefoot, I know some rocks would be slippery. Will this be too slippery / loose for a horse? Or can a horse figure it out? She's pretty tough and I can take her a lot of places, but this would be a first for both of us. I took her right down to the edge yesterday, but chickened out there.