Sandy River uncovers a forest buried by Mount Hood in 1781

by William Sullivan
published April 20, 2013
Salem Statesman Journal
http://www.statesmanjournal.com/article/20130421/COLUMN0402/304200018/Sandy-River-uncovers-forest-buried-by-Mount-Hood-1781

The ancient snags will rot quickly now that they are exposed. You can see the ghost forest on a short loop hike through Oxbow Regional Park near Gresham, just east of Portland. The walk is a sobering reminder of the ongoing danger of Oregon’s volcanoes.

Mt. Hood’s 1781 eruption blanketed the mountain’s slopes with half a foot of ash and created a new lava dome, now known as Crater Rock.

Because previous eruptions already had left thick debris flows in the Timberline Lodge area, the mudflow in 1781 was shunted west. It swept down through Paradise Park, creating that area’s open, treeless slopes. Then it roared past Ramona Falls, filling the Sandy River canyon with a gravel plain that still looks a little stark.

At Old Maid Flat, northeast of Zigzag, a sparse forest of lodgepole pines struggles to grow atop a layer of cobbles and mud 30 feet deep.

At Lost Creek Campground, west of Ramona Falls, a mile-long hiking trail now visits cedar snags that were killed by mud and later exposed by the creek. By counting the rings of similar trees, scientists pinpointed the date of the eruption to the fall of 1781 or the early winter of 1782.

So much debris was left in this area by the 1781 eruption that mudflows continued to wash it down the Sandy River for at least a dozen years.

The mudflows caught the attention of early explorers. British Captain George Vancouver sent Lieutenant W.E. Broughton up the Columbia River in 1792 to scout the Oregon territory. After naming Mt. Hood for a British naval hero, Broughton marveled that the Sandy River had nearly dammed the Columbia with a sand bar.

When Lewis and Clark paddled past in November 1805, they named the present-day Sandy River the Quicksand River. Its valley, they said, was a braided wasteland of debris and dead trees, although they couldn’t imagine why.

Native legends could have given Lewis and Clark an explanation for the devastation. The Multnomah tribe said a jealous chief named Wy’east had been turned into Mount Hood by the Great Spirit. Even as a mountain, Wy’east kept fighting with Mount Adams over the lovely but treacherous Mount St. Helens. In his rage, Wy’east hurled hot rocks, poured fire down slopes, filled valleys with debris and occasionally blew up his own summit.

Geologists today say that accurately summarizes Mt. Hood’s arsenal of natural disasters.

The crater area near Mount Hood’s summit has never completely cooled. A series of fiery eruptions between 1853 and 1865 alarmed pioneer settlers. Newspapers reported that smoke, flames, hot cinders and blackened snow were visible from Portland.

Gas fumaroles in the crater still remain hot enough to boil water. Climbers often remark on the smell of sulfur. A curious climber who ventured too close in the 1930s succumbed to the noxious fumes and died.

Mount Hood might erupt again tomorrow, or it might be quiet for a century. A recent warning came on June 29, 2002, when an earthquake beneath Timberline Lodge measured 4.5 on the Richter scale. Swarms of lesser earthquakes in the past few decades have centered one to three miles beneath Mount Hood’s summit. Other tremors have clustered under the White River Canyon just east of Timberline Lodge. The earthquakes may be caused by rising magma, although geologists aren’t sure.

It’s difficult to predict what Mount Hood’s next eruption will look like, but the greatest damage is likely to be done by mudflows — Mt. Hood’s specialty. If the 1781 eruption is any guide, these torrents of rock, ash and melted ice might actually miss Timberline Lodge. Instead they’ll career east down the White River to the Deschutes River and west down the Zigzag and Sandy Rivers to the Columbia. Along these routes, highway drivers, riverfront homeowners and campers could well be in serious danger when Mount Hood reawakens.

A short hike at Oxbow Park helps you visualize the scale of these volcanic mudflows.

Just seven miles east of Gresham, the whitewater Sandy River winds through Oxbow Park in a deep gorge. In addition to the ghost forest, the 1,000-acre park has a quiet campground, pebble beaches, great blue herons, drift boats and mossy forests of large, living trees.

Although Oregon’s volcanoes have been quiet for more than two centuries, the eruptions of Mount St. Helens in 1980 and Mount Lassen in 1915 served as warnings. We are living atop a portion of the Pacific’s Ring of Fire.

The ghost forest exposed along the Sandy River is a reminder that the Oregon Cascades are very much alive.