Panoramic Photo of Paulina Falls

Ancient, Cataclysmic Flood on Paulina Creek

Photo of Paulina Lake Outlet
Nearly all the clues needed to solve the mystery were right in plain sight — the huge gravel bars, the dry abandoned waterfalls, the actively-migrating falls just below Paulina Lake today, plus the wave-cut terraces marooned several feet above the current lake level. But it wasn’t until two Forest Service researchers, Lawrence Chitwood and Robert Jensen, put all of these clues together back in the mid-1990s that the full story of Paulina Creek’s ancient flood became clear to everyone.

Fortunately for explorers today, all of the evidence and clues for this massive flood are easily accessible on public land, just off the Paulina Lake Road leading up to Newberry Crater. Most sites are just a few hundred feet from the car, while one requires an easy, 1.6-mile roundtrip hike down into the Paulina Creek canyon. See the PDF map download below.

Clue #1: The Missing Mazama Ash
About 7,000 years ago, the eruption of Mt. Mazama, a stratovolcano at present-day Crater Lake, left a distinctive layer of white ash across the Central Oregon landscape. This layer varied from 70’ deep near the mountain to 2’ deep at Paulina Creek. But when investigating archaeological sites along the lower creek in the spring of 1994, Mr. Chitwood first noticed this white ash layer was completely missing across the entire floodplain. Where had it all gone?
Giant Gravel Bar along Paulina Creek

Clue #2: Giant Sand and Gravel Bars
Further investigation at Ogden Group Camp, just below the narrows where the creek enters Paulina Prairie, revealed massive longitudinal sand and gravel bars, up to 8’ high and 50’ across. Also found here were broad low ridges of cobbles and boulders lining the floodplain, with rocks up to 3’ in diameter. It was clear these deposits could only have been left by a much greater flow than that of the present stream.

Clue #3: Abandoned Dry Waterfalls
About five miles upstream, at the present site of Island Falls (aka Footbridge Falls), the researchers found the canyon floodplain divided into two distinct channels, each headed by a waterfall. Paulina Creek now cascades over a small part of the southern waterfall, but the northern waterfall is completely dry and abandoned (photo below). These two deep channels converge about 500' downstream. By now it was obvious that a massive flood had swept away the Mazama ash and left the giant gravel bars downstream, creating these two twin waterfalls in the process.

View of Dry Falls on Paulina Creek

Clue #4: Upstream Migration of Active Waterfalls
It was also now clear that there’d been a massive failure of the basalt sill that was holding back Paulina Lake, creating the cataclysmic rush of water out of the lake and down the stream. Given the active waterfalls just below the lake today (such as Paulina Falls), each gradually migrating upstream as they erode the bedrock, this flood now also had a likely cause: the upstream migration of a waterfall had breached the lake. Indeed, the headward erosion of the falls below the lake today will likely create more sill failures and floods in the future.

Clue #5: Wave-cut Terraces Above Current Lake
As if more evidence was needed, the icing on the cake was the distinct wave-cut terraces along the east and southwest shores of Paulina Lake, which are 5’-8’ feet above the current water level. In fact, the Little Crater Campground and
Wave-cut Terraces above Paulina Lake
Paulina Lake Trail along the east shore of the lake are built on the top of these wide, ancient lake terraces, high above today’s lake level.

Mystery Solved
Putting all of these clues together, the researchers concluded that between 5,000 and 1,700 years ago, the upstream migration of a waterfall led to the failure of the rock sill holding up Paulina Lake, causing the lake level to drop rapidly by several feet. The initial discharge of water is estimated to have been 4,000-10,000 cu. ft. per second, and within 6 hours water was still flowing out at 2,000-5,000 cu. ft. per second. This was a deluge of monumental scale — considering the average flow of Paulina Creek today is about 20 cu. ft. per second!

Download (PDF, 667 KB): Photos of Paulina Creek Flood Features
Download (PDF, 532 KB): Travel Map for Paulina Creek Flood Features
Download (PDF, 272 KB): Chitwood-Jensen Research Report

DISCLAIMER: Every effort has been made to ensure the accuracy of this information, but the authors do not guarantee that it is either current or correct. The reader assumes full responsibility for any use of this information, and is encouraged to exercise all due caution while recreating.

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