The J.E.M. Trail is found just west of the town of Virgin near Zion National Park. Named for trailblazers John, Ellen, and Mike, this trail offers high-speed desert cruising and a cliff-side ride along the Virgin River.The loop is 12.9 miles in length, with 800 feet of altitude gain. The first half is uphill doubletrack; the last 6.2 miles is downhill singletrack. (One-way from the top trailhead, it's 6.5 miles: the first 0.3 miles being doubletrack.) Except for a very short but dangerous switchback section (and a half-mile of cliff-side cruising) it's fairly easy technically.The "badlands" and the alternating bands of red and white of Gooseberry Mesa are mudstone of the Moenkopi Formation, laid down during the early Triassic (about 240 million years ago). As the ocean receded, gravel and shoreline deposits formed the hard Shinarump conglomerate, which begins the cap of the mesa. In the photo above, only a tiny portion of the capstone can be seen. Aerobically, this trail is fairly easy. The first 300 feet of altitude gain is imperceptible as you ride the double-track towards the mesa. Once you reach the base of Gooseberry Mesa, there's a bit of up-and-down, but all doable in the middle chainring.The trail is a fun ride, and definitely worth doing. The views into the chasm of the Virgin River are awesome, and the high-speed singletrack descent is a blast. But if you're only spending one or two days in the area, most bikers would suggest you go to Gooseberry Mesa instead.Most riders start uphill on the doubletrack. From the trailhead (GPS N 37° 12.029' W 113° 13.089', altitude 3320 ft.), backtrack 0.2 miles and turn right on the main gravel road. At 2.1 miles, you'll drop through a big wash. Just a bit further, at 2.3 miles, you turn left off the main road into a shallow wash, or the doubletrack 0.1 mile further on (GPS N 37° 10.726' W 113° 14.326'). The wash and road will cross a number of times, so it doesn't matter which one you take. A singletrack branches off the wash at 2.9 miles, dumping back onto an intersection of the road and the wash at 3.0 miles. You'll see an old corral and a gate just up the road. From here, I suggest you take the road, because the wash gets soft (hard to ride), with some confusing branches. At 4.1 miles, the trail crests at the top of the big wash. (There are a few stock watering tanks here.) Drop down into the wash and head uphill. Follow the road as it dips into and out of the wash. At 4.4 miles, the road forks. Go RIGHT (west). At 5.25 miles, you'll encounter a gate as the road passes around a sandstone canyon on your right. At 6.7 miles, the singletrack branches off on your right (GPS N 37° 08.637' W 113° 14.511', altitude 4160 ft). A rockpile marks the trail. Kowabunga! It's cruising time. Except for a couple of short technical sections, from here you can fly through the desert at motorcycle speeds. At 7.1 miles, the trail walks down the cliff with a steep technical switchback. There's some injury potential here. But it's just a short walk. At 8.4 miles, the singletrack crosses the main road. At mile 11.4, the Hurricane Rim trail forks off on the left, N 37 11.261' W 113 13.862'. Keep right. (Option: take Hurricane Rim to China Wash, then turn south to connect again to JEM about 1.5 miles uphill from where you forked onto the Rim, then retrace back to the fork. Adds about 5 miles to the ride. See GPX or MPS file.) At mile 11.5, the trail drops into the wash. Ride across the rock, and spot the continuing trail on the far side of a second wash. (If you're afraid of heights, you can bail out on the doubletrack road here to avoid riding along the Virgin River Gorge.) You'll ride a mile along the edge of the Virgin River, as it cuts a deep canyon. Then the trail takes you back to the parking area. Getting there: From I-15 north, take the La Verkin exit on UT-17. From the south, take the Hurricane exit on US-9 and go through Hurricane towards Zion National Park. At the junction of US-9 with UT-17, turn east towards Zion. 4.8 miles after the turnoff, turn right (south) on a gravel road signed "Sheep Bridge Rd." 0.5 miles later, you'll cross over the Virgin River. Just uphill is a cattleguard, then a doubletrack on your right 0.1 miles after the bridge. Take the doubletrack 0.2 miles to a turn-around overlooking the Virgin River. The singletrack is at the end of the turn-around. For the loop ride, head back on the dirt road.Upper JEM trailhead: In Hurricane, turn south on US-59 (towards the Grand Canyon). Drive exactly 5 miles uphill. Turn left on cindered doubletrack right as you approach the base of Gooseberry Mesa. Drive another 0.3 miles to the parking area. N 37 08.329' W 113 14.527'