Oneanta Gorge 

v     Oneanta is a narrow steep gorge leading back into the hills for a mile; the sides imbedded with ferns and wild flowers. Along its course runs a silvery stream, fed from beautiful water-falls. This old bridge is part of the original highway which carried motorists over this bridge and through Oneanta tunnel.  The bluff is solid basalt rock which was tunneled to permit the roadway to parallel the railroad in continuing the Columbia River Highway without bridging the railroad or climbing the steep grades. The bluff gives the impression of the one-time rivers that washed over the mountains in the geological period.  The route was changed and the tunnel filled with debris during the 1940s when falling rocks posed hazards. And it was rebuilt & reopened about 2 years ago for foot traffic.

v   Even after a dry spell, Oneonta Gorge is difficult to walk into. I think you always have to walk part-way through water. But after a long rainy spell, it's impossible to enter. I've never been very far into Oneonta Gorge, but I've heard it's a wonderland place in there, once you get past the narrow part, with many plants you never see anywhere else. And the falls is one of the most spectacular in the whole Columbia River Gorge. There’s the narrow passageway into the main part of Oneonta Gorge. Mosses and lichens and ferns — oh, yes — all kinds of plants and trees grow on the Oregon side; the Washington side, being dryer, is not as diverse.

photo courtesy of:  http://www.historicphotoarchive.com/loc/gorge.html