Pounding Pacific waves shape the coast. Even the hard basalt eventually erodes, especially if it is cracked and fractured. Waves compress the air in fractures, forcing them to widen by chipping off pieces of rock, gradually enlarging them into crevasses, caves, and tunnels, finally grinding them down to sand and gravel. Where rock is less fractured, it endures as headland, or if cut off from land, as a sea stack.
About one-half mile off Oceanside are the massive, basalt arched sea stacks, the Three Arch Rocks. Once called the Three Brothers, these stacks, along with the other basalt headlands and offshore rocks, are composed of Miocene Columbia River basalts, specifically Grande Ronde basalts that erupted from volcanic fissures in southeastern Washington and northeastern Oregon 15.6 to 16.8 million years ago and flowed over large parts of Washington and Oregon, down what is now the Columbia River drainage, all the way to the coast. Three Arch Rocks were once part of Maxwell Point before erosion separated them into individual stacks.
The Arches make up fifteen acres of wildlife refuge that are home to over a quarter million roosting, breeding, and nesting seabirds that include common murres, tufted puffins, Brandt's cormorants, pelagic cormorants, fork-tailed storm petrels, guillemots, brown pelicans and other seabirds. Also found there are bald eagles, peregrine falcons, harbor seals and the huge Steller sea lions. The refuge consist of three large rocks and six small rocks, four of which Finley Rock, Middle Rock, Seal Rock and Shag Rock support breeding colonies of seabirds. Thirty percent of Oregon's Common Murres and 60 percent of the state's Tufted Puffins nest on these rocks. Finley Rock is the highest at over three hundred feet. The tunnels through the three largest stacks were slowly carved by the relentless pounding of breakers rolling in from the Pacific. The stacks extend vertically to a depth of about 60 feet, their sides rich with rock scallops, and are home to lingcod and sea bass. Around the stacks, the bottom is rugged and undulating, covered with boulders and underwater spires that stand thirty or more feet high.
Three Arch Rocks is the oldest National Wildlife Refuge west of the Mississippi River, created as a result of the efforts of two early wildlife photographers and conservationists, William Finley, Oregon’s first State Biologist, and Herman Bohlman, a nature photographer. Concerned about egg gathering and the wildlife devastation brought about by marine mammal hunting and the killing of seabirds by local sport shooters who came to the rocks on Sundays for target practice, Finley and Bohlman began in 1901 to study and photograph The Arches as support for the establishment of a wildlife sanctuary. During the summer of 1903, after several failed attempts, they rowed a dory to Shag Rock where they camped for fourteen days, photographing birds. Later that year, Finley took the photographs to Washington and personally showed them to Theodore Roosevelt, lobbying for protection of the birds. Finley and Bohlman continued their efforts in both Washington and Oregon for the passage of laws for seabird protection. The Oregon State Model Bird Law was signed, and the Three Arch Wildlife Refuge was established by Roosevelt on October 14, 1907. Today, this National Wildlife Refuge is off-limits to the general public to prevent disturbing nesting birds and cannot be approached by boats closer than 500 yards between May 1 and September 15.
Additional Reading:
Bishop, Ellen Morris. 2003. In Search of Ancient Oregon - A Geological and Natural History. Timber Press.
Fraser, Mary Ann. 1994. Sanctuary - The Story of Three Arch Rocks. Henry Holt and Company.
Orr, Elizabeth L. and William N. Orr. 1999. Geology of Oregon. Kendal/Hunt Publishing Company.
