Waterfall Wednesday #3

Multnomah Falls

Situated along the Historic Columbia River Highway, this iconic waterfall is the tallest in Oregon at 620 feet tall. Multnomah Creek plunges 542 feet over the upper falls into a pool, then gradually drops 9 feet over a basalt layer before plunging again 69 feet over the lower falls into another pool below. The 49-foot long footbridge was constructed in 1914 by Italian Stonemasons at 105 feet above the lower falls.

The Geology of Multnomah Falls

There are two main events, or rather, two main type of events that happened multiple times, that helped create the Multnomah Falls. Before 16.5 million years ago, Multnomah Creek would have been a regular mountain stream with small cascades as it made its way to the Columbia River. Between 16.5 and 14.5 million years ago, large amounts of basalt poured out from northeastern Oregon and flowed toward the sea. As the flowed down the Ancestral Columbia River Valley, they filled all the low spots such as the lower part of Multnomah Creek. After that event, the new Columbia River was pushed a slightly northward and possibly flowed over a magnificent waterfall near the mouth of the river, or even near the present-day city of Portland. The next massive events that came happened during the last Ice Age, where the Columbia River Floods gouged out a channel in the basalt over and over until it became close to what the Columbia River Gorge looks like today. Since the end of the Ice Ages, Multnomah Creek has been eroding the basalt away to create the waterfall you see today. In fact it is still eroding as we look at it, sometimes only a sand grain at a time, other times, although rare, a chunk of rock breaks off like the boulder in 1995 did.

If you feel like viewing Multnomah Falls, make sure you take appropriate gear if you go in winter, as there could be ice along the trail. The trail is quite steep, but it is all downhill on the way back. Until next time, get outside and enjoy hiking to one of the many waterfalls in the great Oregon Outdoors.