How to create a path for prom?

So this year, for our school's Junior Senior Banquet (prom), we are planning on a black and white theme- we're hoping it will seem like a walk through the park at night. We have everything rented and painted. And we had made a black fabric path. However, the insurance policy of the building we are using will not allow fabric on the ground (because of people tripping, etc.) So, we were thinking rocks along the sides to suggest a path. But now we're concerned that girls' dresses might catch on the rocks and drag them along. Any suggestions for a simple, safe, and practical way to create a path?