Arch Cape Creek, Arch Cape

Arch Cape Creek, Arch Cape

by | Apr 18, 2022

Arch Cape is a small community at the mouth of Arch Cape Creek named after a natural sea arch in a basalt headland, about 25 miles (40 km) north-northwest of Tillamook and 6.5 miles (10 km) south of Cannon Beach, Oregon. Arch Cape Creek flows generally west for about 4 miles (6 km) draining a Coast Range watershed that heads between Onion Peak to the north with an elevation of 3,057 feet (932 m) and Angora Peak to the south with an elevation of 2,682 feet (817 m). The watershed is mostly underlain by the Astoria Formation sandstones and Depoe Bay basalt. The rocks in the Arch Cape area were deposited during the Miocene approximately 35 to 13 million years ago. During that time, a shallow marine embayment formed and great quantities of sand, mud, and gravel were transported westward by an ancestral Columbia River from the early Cascade Mountains. These sediments were deposited in the form of a large delta and lithified and then intruded by magma. During the Pliocene which lasted from 13 to 3 million years ago, these rocks were uplifted, faulted, folded, and eroded to form the Coast Range. The Astoria Formation in this area is composed of sandstone with a thickness of up to 1,100 feet (335 m). The peaks at the head of the watershed and the erosion-resistant headlands on the coast are composed of Depoe Bay basalt with a thickness of more than 2,000 feet (610 m) at Onion Peak. During the Pleistocene from 13 million to 11,000 years ago, erosion became the dominant regional process, excavating valleys in the softer sandstones and leaving the harder basalt dikes as elongated narrow ridges and basalt sills as high rugged mountains. A layer of dune and beach sands, and stream alluvium including gravel, silt, and sand were deposited as marine terraces. Sea level fluctuated several times during the Pleistocene owing to the development of continental glaciers and their subsequent melting. As a result, wave-cut benches representing former elevations of the sea lie 40 to 100 feet (12-30 m) above present sea level along this part of the Oregon coast. The community of Arch Cape is situated on a marine terrace where wave erosion planed the surface flat. Since the Pleistocene, waves have been carving a new wave-cut bench below the surface of the water and have been eroding away parts of the less resistant rocks to form stacks, caves, notches, cliffs, and narrow sand beaches, leaving the more resistant headlands, such as Arch Cape.

The marine terraces of the Oregon coast have been inhabited by Native Americans for thousands of years, most recently by the Clatsop people, a Chinook-speaking tribe that inhabited the northwest coast of Oregon. The Clatsop people were historically hunters and gatherers living in small villages typically located on salmon spawning streams that consisted of family lodges made of cedar planks. They made canoes of cedar logs, first hollowed out by fire, then shaped and finished with stone or bone tools. Food bowls and utility vessels were fashioned from stone, wood, bone, and shell. Mats and baskets for food storage were woven using hide, vine, grass, and bark. The Clatsop practiced head flattening, where infants were bound across the forehead with a strong piece of bark or wood that was tied firmly at both ends to the cradleboard. The first documented contact with Euro-Americans was in 1792 when Captain Robert Gray reported the tribe in his journals. In 1805, the tribe was encountered by the Lewis and Clark Expedition and the Clatsop shared salmon, berries, and hunting tips with the Corps of Discovery. In an 1851 treaty, the Clatsop tribe proposed to cede 90 percent of their land to the U.S. Government but this treaty was never ratified by the Senate. They are one of the tribes in Oregon that were not forced onto reservations, however, the Clatsop today have no federal recognition as a tribe and have struggled to retain their communal identity. In 1891, the Arch Cape post office was established for a remote hamlet at the end of a wagon road with weekly mail delivery on foot or horseback. Before the Oregon Coast Highway was built, the only way to reach Arch Cape was from the north and to travel along the beach at low tide. In 1936, the Oregon Coast Highway ended just south of Arch Cape Creek, and work had begun on a tunnel through Neahkahnie Mountain that was completed in 1940 and is presently 1,228 feet (375 m) long.

Ocean waves generated by energetic winter storms typically remove sand from beaches while lower energy summer waves deposit sand. The removal of sand from the beach at Arch Cape occasionally uncovers giant tree stumps estimated to be at least 4,000 years old. These ancient stumps are from prehistoric cedar and possibly redwood trees. In 2008, Oregon Parks and Recreation Department staff also removed a pair of historical cannons from the schooner USS SharkShark was constructed in Washington D.C. and launched in 1821. The vessel was 86 feet (26 m) long, displaced 198 tons, and carried 12 guns, 10 of which were 18-pound carronades, and 2 were 9-pounder guns. Shark first sailed off the coast of Africa, the West Indies, and New England, and in 1833 was transferred to the Pacific Squadron to protect American interests. In 1846, under the command of Lieutenant Neil M. Howison, Shark crossed the bar off the mouth of the Columbia River for explorations in the lower Columbia and Willamette Rivers while staging out of the British Fort Vancouver. After several weeks in the vicinity of the fort, the vessel returned to the mouth of the river, and despite making new observations of the bar in preparation for crossing, struck an uncharted shoal and was swept into the breakers. The vessel was a total loss, but her entire crew was saved. Hudson’s Bay Company officers at Fort Vancouver immediately coordinated and dispatched a relief effort, including food, tobacco, and clothing, and the crew returned to Fort Vancouver. Howison received word that a group of Clatsop found part of the hull washed ashore 20-30 miles (32-48 km) south of the accident. A midshipman named Simes was dispatched to visit the site and found wreckage near the mouth of present-day Shark Creek at Arch Cape. He reported that three of the ten carronades were part of the wreckage but determined that transportation of the heavy guns over the rough mountain trail was impractical and they were abandoned. In 1898, mail carrier Bill Luce found one of the cannons on the beach and a team of horses dragged the gun out of the sand. It is now on display in Cannon Beach, Oregon. Two additional cannons were found on the Arch Cape beach in 2008 and are on display at the Columbia River Maritime Museum in Astoria, Oregon. Read more here and here. Explore more of Arch Cape here:

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This ‘warming stripe’ graphic is a visual representation of the change in global temperature from 1850 (top) to 2021 (bottom). Each stripe represents the average global temperature for one year. The average temperature from 1971-2000 is set as the boundary between blue and red. The color scale goes from -0.7°C to +0.7°C. The data are from the UK Met Office HadCRUT4.6 dataset. 

Credit: Professor Ed Hawkins (University of Reading). Click here for more information about the #warmingstripes.

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