Only a few hundred feet east of Oneonta Gorge [1] is Horsetail Falls, which drops out of a notch in the rock to fall 176 feet. While the waterfall is easily seen from the turnout along U.S. 30 [2], hikers should consider the three-mile Horsetail-Oneonta Loop Trail.
Starting at Horsetail Falls, the trail quickly climbs up the side of the gorge wall and along the edge of a lava flow. The trail continues behind Ponytail Falls (also called Upper Horsetail Falls), which pours out of a tiny crack into a mossy cirque. The trail then drops onto Oneonta Creek, with great views over the narrow gorge and waterfalls.
The trail returns to U.S. 30 about 0.5 miles west of the Horsetail Falls trailhead.
Links:
[1] http://www.moon.com/destinations/oregon/columbia-river-gorge/historic-columbia-river-highway-us-30/sights/oneonta-gorge
[2] http://www.moon.com/destinations/oregon/columbia-river-gorge/historic-columbia-river-highway-us-30