Ranges like that are actually normal. Many places will use old tractor tires filled with sand and dirt, or stack up sections of old railroad ties with dirt or sand between them. That stuff will stop basically everything under the sun that would show up at the range, unless someone showed up with a 25mm chain gun. Then you're screwed.
It's a bit unnerving if you're not used to it, but once you are, it's not an issue.