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Sea Stacks: Washington and Oregon Coasts

Sea Stacks: Washington and Oregon Coasts
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Sea stacks stand off shore of the Pacific Northwest Coasts all up and down Washington and Oregon. They are bird sanctuaries, and often have shellfish (our family would get mussels off of Haystack Rock and other sea stacks off of Cannon Beach, Oregon when I was a kid – my sister always dug it – even before I became one, I was a vegetarian at heart, however).

Sea Stacks Caused by Erosion

Sea stacks off the shores of Ruby Beach provide habitat for western gulls, tufted puffins, and bald eagles.

Sea stacks off the shores of Ruby Beach provide habitat for western gulls, tufted puffins, and bald eagles.

In general, they form from erosion caused by coastal geomorphology. Erosion along rocky shores results from differential decomposition of the various materials along the coastline. This is not only caused by the material, but by wave energies. Wave energy varies from location to location, both vertically and horizontally. The combination of material and wave energy variations result in rocks sculpted from all sides. Voilá! Sea stacks!

Cormorants nest on sea stack off the shore of Yaquina Head Outstanding Natural Area on the central Oregon Coast. This area was one mile inland just a few hundred years ago. The Oregon coastline is quickly receding (from a 2009 GSA field trip). Yaquina Head itself is an eroded Miocene volcano (Snavely and Macleod 1971:93).

Cormorants nest on sea stack off the shore of Yaquina Head Outstanding Natural Area on the central Oregon Coast (from a 2009 GSA field trip). This area was one mile inland just a few hundred years ago. The Oregon coastline is quickly receding. Yaquina Head itself is an eroded Miocene volcano (Snavely and Macleod 1971:93).

Sea Stack in the Making: Collapsed Sea Cave

The Devil’s Punch Bowl, within Devil’s Punch Bowl State Park on the central Oregon Coast, may be a sea stack in the future. Apparently, it is a collapsed sea cave, according to a 1971 State of Oregon geology paper by Parke D. Snavely and Norman S. Macleod called Visitor’s Guide to the Geology of the Coastal Area Near Beverly Beach State Park, Oregon (p. 98) in The Ore Bin (the Geology Journal of the Oregon State Department of Geology and Mineral Industries (DOGAMI).

The reason why Devil’s Punch Bowl might be a sea stack in the making is that collapsed caves often transform into sea stacks as they continue eroding and separate from the headland.

Now a collapsed sea cave, Devil's Punch Bowl on Oregon central coast may be a future sea stack if it goes the route of other collapsed sea caves. In fact, a sea stack stands in the upper left-hand corner of the photo. This is also a good spot for whale-watching.
Now a collapsed sea cave, Devil’s Punch Bowl on Oregon central coast may be a future sea stack if it goes the route of other collapsed sea caves. In fact, a sea stack stands in the upper left-hand corner of the photo. This is also a good spot for whale-watching.

Sea Stacks and History: Lewis and Clark (alrighty, but they no doubt saw them!)

Cannon Beach on the northern Oregon coast is really where I first got to know sea stacks. We spent a lot of time there as a kid (it was a lot cheaper than it is now). I spent more than one birthday at Ecola State Park (from where the picture below was taken). I wasn’t the only one. The Lewis and Clark Expedition wintered there over 1805-1806. On January 6, 1806 (according to the Indian Beach, Ecola Beach State Park sign), they set off from Fort Clatsop to harvest a beached whale off of Cannon Beach. It was on the shore south of the sea stacks in the picture below (just south of Ecola but right on Cannon Beach). It was just past Ecola Creek beyond the photo’s scope. By the time they reached the whale, only the skeleton was left. I’m afraid that our family had a much better time than them at the beach. Both Ecola Creek and Ecola State Park are named after the whale.

The ekkoli (whale in Chinookan) was on the shore south of (beyond) the sea stacks in the photo. The Lewis and Clark expedition found only a skeleton left when they set to find it from Fort Clatsop on January 6, 1806.

The ekkoli (whale in Chinookan) was on the shore south of (beyond) the sea stacks in the photo. The Lewis and Clark expedition found only a skeleton left when they set to find it from Fort Clatsop on January 6, 1806.


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