Cape Kiwanda's Sinkholes Merging, N. Oregon Coast Landmark a Little More Dangerous

Published 06/21/23 at 10:21 p.m.
By Oregon Coast Beach Connection staff

(Pacific City, Oregon) – Just as one geologist predicted, the large sinkhole atop Cape Kiwanda not only got bigger but another one developed nearby. Now, the Oregon coast landmark is seeing those two sizable holes merge into one, perhaps pointing to a faster decay than local officials had thought. (Above: the two sinkholes are currently covered in sand, but they are joined underneath that thin layer. Courtesy Oregon State Parks)

Back in January of 2023, the first one opened up, causing Oregon State Parks and Recreation Department (OPRD) to put a fence around the area. A few months later, a second one emptied out sands not far from it. From the start, Seaside geologist Tom Horning told Oregon Coast Beach Connection he predicted a second one would appear and it did. He also hinted these would grow and that it was entirely possible this section of the cape could fall apart.

This week, OPRD reports the two sinkholes are definitely beginning to merge. However, recent strong winds caused sands to cover up the openings, giving a false sense of stability to the increasingly-dangerous area.

Courtesy OPRD: the two sinkholes were already very close when the second developed in May

Park manager Jason Elkins said the fencing keeps growing now as more of the area is eaten away.

“ This additional fencing was installed with an abundance of caution until we can determine how large the void underneath the sinkholes is as well as how much of the area is unstable,” Elkins said. “We are working with Oregon Department of Geology and Mineral Industries (DOGAMI) to evaluate the conditions and determine where to relocate our permanent fence for safety.”

OPRD flew a drone over the area, and with the help of geologists from DOGAMI discovered what Horning had predicted earlier this year: that a cavern had formed at this western edge of Cape Kiwanda.

Current photo courtesy OPRD

The Seaside-based geologist has studied Cape Kiwanda himself and even led geology tours around there. He told Oregon Coast Beach Connection there was likely a cave down below hundreds or maybe even thousands of years ago, and that was filled up with debris over time. These days, whatever had filled in has gotten pulled back out with all that wave action at the front of Kiwanda. Hence the giant openings.

Indeed, according to Oregon Public Broadcasting, the drone flights have caught sight of yetanother hole developed beneath the cape, a ways to the north of these two, state geologists found.

Current photo courtesy OPRD

Horning was able to tell by the photo earlier this year that the sand around the sinkhole was finer, smaller. That comes from being under pressure for a long time, which is an indicator this was a cave that was filled up and then had that fill removed by strong surf.

“Cape Kiwanda is continuing to be eroded this way, washing out sand that blew in a long time ago and filled the cave,” Horning said earlier this year. “ And so I think that it's going to be pretty hard to stop this thing from finding its own equilibrium. My advice is to keep pushing the fences back – the thing just grows. Just let it do its thing.”

The Oregon coast favorite is made of a sandstone that is much more easily eroded away. In fact, large chunks of the headland fell apart on the northwesternmost tip of the structure, one big section two years ago and then another in 2011. Both left massive boulders at the site. See 2nd Sinkhole on Top of Cape Kiwanda Spells Bigger Dangers, Says Oregon Coast Geologist

Horning knew awhile back there are sea caves down there, some in really long configurations, like one that's approximately 150 feet long. The small “spouting horn” at the “mini cove” at the southwestern edge of Cape Kiwanda is proof of that. Horning could tell some channel was underneath everything, feeding water beneath the crack that allows the water to shoot through. See Cape Kiwanda geology.

Elkins said the public needs to stay away from this barrier, keep pets on leashes and children from the edges of the cape.

“If you see something that concerns you, leave the area and report it to Cape Lookout State Park staff at 503-842-4981. In an emergency, call 911. Oregon Parks and Recreation Department is continuing to monitor the situation,” Elkins said.

Oregon Coast Beach Connection suggests you stay back much farther than the barriers. The two holes merging is a bad sign and happened rather fast. Horning's predictions about a chunk of this spot falling apart could come true much faster than thought. [See Complete Guide: Cape Kiwanda State Natural Area]

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Andre' GW Hagestedt is editor, owner and primary photographer / videographer of Oregon Coast Beach Connection, an online publication that sees over 1 million pageviews per month. He is also author of several books about the coast.

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