Two days ago I went on an overnight backpack with two other guys, It was a 5.7 mile gradual uphill hike from 6,000 ft. to 8,000 ft. to the Hidden Forest area. But it was all on gravel from 3/4" size to fist size but mostly "in-between" size with some loose, corarse sand as well in some stretches. This was in in Deadman's Canyon in Southern Nevada's Desert National Wildlife Refuge, the largest NWR in the nation. The gravel was all from water flow deposition. I want to tell you that this is the damnedest walking surface I've ever done, including some very rocky sections of the Appalachian Trail in Pennsylvania (also known to AT hikers as "Rocksylvania"). Almost every step in the NWR trail on moveable rocks of various sizes. I would have paid to walk on a "normal" dirt trail. The second day my legs were fine but today, the day after the hike back down to the trailhead, my legs are sore, mainly my calves. I mean, c'mon, I've been training with a 30 lb. pack on mountain trails near my home and my backpack for the Hidden Forest trip was only 25 lbs. so it's not like I was not ready for the trip. I hope to hell to never, ever walk on gravel like that again. Eric B.