Will the slate tiles hold up to our winters?

We are considering using slate tiles for a walkway/courtyard entry.  We are in eastern Washington.  Will the slate tiles hold up to our winters?  If so. we have natural occurring granite underneath with layers of gravel and sand, will that be stable enough to place the tiles directly into the sand or would we still have to make a concrete slab.
 

Thanks,

Jsb, april 3