Multnomah Falls
Falls  
"... we passed several beautiful cascades which fell from a great hight over the stupendous rocks which cloles the river on both sides nearly ... the most remarkable of these cascades falls about 300 feet perpendicularly over a solid rock into a narrow bottom of the river on the south side. it is a large creek, situated about 5 miles above our encampment of the last evening. several small streams fall from a much greater hight, and in their decent become a perfect mist which collecting on the rocks below again become visible and descend a second time in the same manner before they reach the base of the rocks. ..." [Lewis, April 9, 1806]

Multnomah Falls is the most visited natural attraction in Oregon. Over 2.5 million visitors a year come from every part of the world to view the lush foliage, tall firs, and towering cliffs that form the spectacular backdrop to the second highest year-round waterfall in the United States. Multnomah Falls is the highest waterfall in the Columbia River Gorge with a total drop of 620 feet. The falls is fed by underground springs from Larch Mountain.

A steep paved trail leads visitors to a platform above the falls. The waterfall is visually complimented by Benson Bridge, built in 1914 by Italian stone masons, and Multnomah Falls Lodge built in 1925. Inside the Lodge is a gift shop, restaurant, and U.S. Forest Service Information Center.

Major improvements were made in 1994 to the lodge, including access for those with disabilities, enlarging the outdoor dining terrace, improving and relocating the restrooms and snack bar and adding a fully-appointed interpretive information Visitor's Center.

Lumber baron Simon Benson, an avid philanthropist, donated funds for the land encompassing Multnomah Falls and for the 1914 construction of the Benson Bridge, which spans the chasm above the lower falls. Multnomah Falls park was dedicated in 1915.

Ten years later Multnomah Falls Lodge, now a National Historic Landmark, was constructed at a cost of $40,000. The stone and timber "Cascadian" style building was designed by noted Portland architect Albert Doyle. In 1939 the city of Portland transferred ownership of the park and lodge to the US Government. The US Forest Service has administered the site since then.

Multnomah Falls Lodge was threatened by a wildfire in the 1990's. You can still see the nearby husks of burned trees where the blaze came to within feet of this historic building. Steep cliffs and difficult terrain made the fire hard to battle, but firefighters, using helicopters with 1000 gallon buckets to dip water out of the Columbia River, were able to douse the blaze and save the lodge.

Rapid uplift of this region over the last two million years has forced the Columbia River to incise the Gorge as seen today. However side streams, like Multnomah Creek, did not have the erosive power of the Columbia River and were left behind to plunge off the Gorge's basalt cliffs. Multnomah Falls is a "side-effect" of the geologic origin of the Gorge.

While the spectacular geology of Multnomah Falls appears timeless, the rock face is continually being worn away by the force of the waterflow. This fact was highlighted on Labor Day, September 4, 1995, when a large rock slid from the face of upper Multnomah Falls due to the natural process of erosion and dropped into the upper plunge pool. The spot where this 400 ton boulder broke off is easily identifiable as a flat, tan colored area where the water is splashing on the rock (during times of low water flow). It fell 225 feet and created a splash of 70 feet, spewing water and small rocks that flew over the Benson bridge. A wedding party just happened to be on the bridge for photos when the boulder fell. 20 people had minor injuries from flying, gravel size rock chips, including the groom who was struck by flying rock in a particularly delicate part of his anatomy. His bride reported the next day in The Oregonian that, despite his injuries, he had still been able to bravely perform his conjugal duties.

Geology:

Multnomah Falls drops 620 feet over Grande Ronde Basalt of the Columbia River Basalt Group (CRBG). The two drops of Multnomah Falls were produced because of a more easily eroded zone at the base of the upper falls.

"... Observations of waterfalls over Columbia River basalt have shown that falls often occur where flows are flat lying or dipping upstream. This condition allows blocks produced by vertical joints to remain stable until support is withdrawn by erosion of softer interflow material at the base of individual flows. The rate of erosion of interflow areas probably largely controls the rate of retreat of the falls. ... The amphitheater-shaped valleys common to many of the falls within the Gorge are due to the freeze-thaw action of water from the splash mist that has penetrated the joints. ..." [Norman and Roloff, 2004]

At Multnomah Falls the visitor can view six lava flows in the cliff face, with pillow flows being visible in the upper sequence near the lip of the Upper Falls. Five more flows of Grande Ronde basalt can be seen along Multnomah Creek along the trail above the falls. The cliff of Multnomah Falls was enhanced by the flood waters of the Missoula Floods thousands of years ago when the flood waters eroded away softer material, highlighting the spectacular cliff face.

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