Fort Stevens State Park: What's Really Underneath This Oregon Coast Historical Site

Updated Periodically
By Oregon Coast Beach Connection staff

(Warrenton, Oregon) – Up on the north Oregon coast, Fort Stevens State Park has more than just the obvious history. Striking, eye-popping and realtime examples of the past are sitting all around you: the wreck of the Peter Iredale, Battery Russell, and several other physical objects and buildings – including a whole other military complex only open some parts of the year.

What’s behind it and beneath it - geologically - is rather shocking, however.

Did you know that parts of Fort Stevens didn't exist before 100 years ago?

The building of jetties at the mouth of the Columbia River in the 1890's allowed a mindbogglingly large chunk of land to be created. Many of the ponds and wetlands you see along the road going to the south Jetty weren't there when Lewis & Clark wandered these shores.

According to one lidar map from north Oregon coast geologist Tom Horning, something like a half mile of shoreline around the western side of Fort Stevens were not there until after the building of the jetties. They were inadvertantly manmade.

Horning said the changes happened quite quickly. Within a few years a lot of sand and land were added to the area.

Yet the growth of the shoreline continued, with dunes building westward as much as 20 feet each year since the early days of the Columbia River jetties. This doesn’t mean the entire shoreline kept growing that much – but it’s helped.

Essentially, according to Horning, what’s happened is sand keeps getting shuttled down from the Columbia River. Construction of the jetties really pushed this along, but continuous dredging of the shipping channel also keeps the sediment flowing.

“This ebbtide delta has served as a large sediment reservoir for longshore currents to transport sand north and south to build coastal beaches,” Horning said.

It’s entirely possible all this shoreline growth along the north Oregon coast and southern Washington coast has ceased and may be degrading now. Climate change and higher storm surges are playing a part, but so is something else manmade.

Studies done by Oregon State University geologists have found that while so much has been lobbed onto the area by the changes in sediment and sand distribution, these areas are very vulnerable to erosion. Peter Ruggiero, a geology professor at OSU, wrote a paper several years ago that showed all this newly-created sections of shoreline are still not yet stable. Nature has not figured out if it's halted taking sand away or if it's still depositing more.

Beaches to the north and south have been affected to large degrees. Ruggiero has said that parts of the southern Washington coast may be more vulnerable to disappearing than farther south.

In explaining this, Horning mentions a “littoral cell,” which means the space between headlands. In this case, we’re talking about the 30-plus miles between Cape Disappointment in Washington and Tillamook Head by Seaside.

“The many dams on the Columbia and its tributaries have created sediment sinks that intercept river sediment, preventing it from reaching the Clatsop beaches,” Horning said. “This will cause the sediment budget of the littoral cell to reverse itself and begin to obtain sand by eroding beaches and dunes, rather than providing it via ocean currents and winds. This commonly understood hazard will most likely begin to reveal itself in the next 20 to 50 years, mostly during storm surges, when large surf coincides with monthly high tides. Rather than dunes prograding westward, they will eventually begin to retrograde eastward.”

In other words, like much of the Oregon coast and Washington coast, Fort Stevens too is looking at shrinking. Lodging in Astoria/Seaside - Where to eat - Astoria / Warrenton Maps and Virtual Tours

MORE PHOTOS BELOW

More About Oregon Coast hotels, lodging.....

More About Oregon Coast Restaurants, Dining.....

LATEST Related Oregon Coast Articles

Back to Oregon Coast

Contact Advertise on BeachConnection.net
All Content, unless otherwise attributed, copyright BeachConnection.net Unauthorized use or publication is not permitted