Around here you can ride Cyclocross bikes on fire roads but they usually aren't slick tires. Depending on the composition (how big the rocks are, etc) it may be possible. I think if you have rails to trails you could do it but it is easier to have slightly knobby tires for traction.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan