Anyone who has made a few trips through the Columbia Gorge has noticed the small monolith that pokes out of the center of the river near Cape Horn. This is Phoca Rock, and its distinction lies partly in the fact that it is one of the few landmarks in the Gorge that carries the name given by Lewis and Clark on their 1805-06 Corps of Discovery journey.
Lewis and Clark didn’t actually name the rock until they were camped on the Oregon Coast, and compiled their journals while suffering through a dank Northwest winter. William Clark named the rock for the abundant harbor seals spotted in the river – phoca vitulina.
Harbor seals are still native to the lower Columbia River, although in smaller numbers than when Lewis and Clark paddled through. Government bounties in Oregon and Washington killed more than 20,000 Harbor seals in the two states from the 1920s through 1972, when hunting was finally banned.
The Harbor seal population has since rebounded from fewer than 7,000 seals at the time of the ban to more than 17,000 today. Still, biologists in both states must monitor the seals for health and impacts from commercial fisheries.
Phoca Rock continues to serve as a river beacon today, marking the edge of shipping lanes on the Columbia. The rock marks the edge of two-foot shallows along Oregon’s Sand Island and the 45-foot deep Candiana Channel that separates Phoca Rock from Cape Horn, on the Washington side.
Clark estimated the rock to be 100 feet tall, but today we know it to be just 30 feet. Its prominence lies in its isolation, and early names for the rock underscored this point: beginning in the mid-1800s, Phoca was alternately called “Hermit’s Islet”, “Lone Rock” and “Sentinel Rock” before the federal government finally restored the original name given by Lewis and Clark, in the early 1900s.
So, why is Phoca Rock sitting alone, in the middle of the Columbia River? Chances are the rock isn’t a tiny cousin to nearby Beacon Rock, the exposed, solid core of an ancient volcano. Phoca is more likely an outcrop of the Grande Ronde basalt flows that produced the cliffs of Cape Horn, to the north, and the Pillars of Hercules, along the Oregon shore.
Diminutive Phoca Rock is as tough as it is tiny. The rock survived multiple Missoula Floods, after all, and thousands of years of parting the waters of the Columbia River. And left alone, Phoca Rock will continue to weather the elements for millennia with little change, long after the ribbons of asphalt and steel that line the Gorge have vanished.