Scenic Rowena Crest and the Tom McCall Preserve area provide an incredibly scenic place to let your feet, and your imagination wander as you look out on a major chokepoint along the Ice Age Floods path. The wildflower displays are amazing during the Spring, but several compelling flood-related features are visible from the vantage of the Rowena Crest Viewpoint any time of year. Rowena Crest lies nearly 700 feet above the Columbia River at the upstream end of the Rowena Plateau, a miles-long plateau that the river flows along. Just upriver from the plateau is the narrow section of the Gorge known as the Rowena Gap The drive to the viewpoint on old Hwy 30 from either east or west is a spectacular ride through a wonderous section of the Columbia River Gorge. A roundabout parking area at the viewpoint, with a safety wall above a sheer cliff, provides a great observation point eastward toward Rowena Gap. At Rowena Crest it’s easy to imagine what it might have been like to witness the approach of those massive floods.
There is not yet scientific evidence that humans were in the area to bear witness to the Ice Age Floods, but there is solid evidence of humans in the Americas by that time. And there is growing concensus that if they came in during a glacial maximum, they would have come in by a coastal route that offered plentiful food and shelter for their journey. The mouth of the Columbia River would have been the first major waterway path inland that might have led them to settle in the area of the Floods.
Your village might have been situated across the Columbia at the mouth of the Klickitat River where the town of Lyle now sits. If you were foraging, or just relaxing, atop Rowena Crest on a late summer day, you might have felt the ground begin to temble as if there were a small earthquake, but the trembling would have slowly increased for a few hours. Eventually you would have heard a low roaring sound that also grew over an hour or more before you could see turbulent brown muddy water begin flooding across the broad basin to the east.
Then the roaring flood of water, only a few feet deep at first, would have entered the narrows, now called Rowena Gap, and sped on, crashing against the promontory you’re standing on and being diverted toward your village which was quickly washed away by the muddy torrent. But the muddy flood waters would have kept rising, unlike the Spring floods you’re used to on the Columbia, becoming a hundred feet deep, then two hundred as the levels just kept rising. Soon a huge whirlpool formed in the flood waters near the base of the promontory and a giant eddy formed where your village had been as flood waters flowed backward up the Klickitat River even as the bulk of the water continued downstream on the main stem of the Columbia.
As the flood waters reached 400 and 500 feet deep and kept coming, suddenly to your right a huge block of the promontory broke off and slumped down into the rampaging flood waters. Now you would have begun running south toward higher ground, climbing higher and higher as the still rising flood waters poured across the plateau and plunged into the small creek valley to the west, tearing away at the valley walls and massively widening that little valley. Eventually the flood waters stopped chasing you upward as you climbed higher, 200 then 300 feet above the now submerged promontory. Now as you turned and looked out across that expanse of muddy water you could see massive white blocks of ice being carried along on the flood waters, similar but inconceiveably larger than the ice blocks carried on the river during the Spring floods.
But the flood waters didn’t begin to recede that day, nor the next, as they might in the Spring floods. In fact it was almost half a lunar cycle before they began to slowly recede, exposing a mud coated Columbia River valley that was now noticably wider, with layers of shear vertical rock walls extending over 1000 feet above the normal river level below. As you began the recovery from the floods devastation, your family returned from from their hunting and gathering in the high mountain meadows, and you have an incredible story to pass along to them and your ancestors.
This story is easy to imagine as you look out to the east from Rowena Crest. The onrushing Ice Age Floods waters easily flowed over the low relief of the broad Dalles Basin to the east, but the major Rowena Gap created a chokepoint in the path of the floods as they made their way through the Columbia River Gorge. This “hydraulic dam” forced the flood waters to build to over 1000 feet deep in this area, flowing hundreds of feet deep over Rowena Crest while forming a temporary lake in The Dalles basin. It is estimated that many of the 40-100 Ice Age Floods may have taken up to a month to completely flush through the system to the Pacific Ocean, but the duration of the flood waters at any point along the path probably lasted less than a couple of weeks. But this was more than enough to create several major floods features visible from this vantage point.
At Columbia River level below and east of the promontory is a round Kolk pond that was created by giant whirlpools in the flood waters as they were deflected around the Rowena Crest promontory. Other similar Kolk features can also be seen on the Dallesport area to the east, and along the hiking path atop Rowena Crest where they are marked by surrounding groves of oak trees.
grew Across the Columbia, the floods deposited a huge eddy gravel bar that the entire town of Lyle, Washington is built upon. The Klickitat River was backed up for miles upstream, as evidenced by upstream growing sand and gravel beds in a quarry over 400 feet above the Columbia River at the junction of Old Highway 8 and Canyon Road.
Below the edge of the viewpoint, a number of large tilted blocks of layered of Columbia River Basalt are slump blocks, undercut by the flood waters crashing against the promontory, thatbroke off and slid toward the river from the prominent indentation in the cliff face just to the south of the overlook. These slump blocks can also be clearly seen from the Washington side of the River.
The ephemeral Rowena Creek flows through a massively oversized valley to the west of the Preserve area, and hundreds of low, rounded mounds cover the Preserve area. These enigmatic mounded features are variously called Mima-, Desert-, or Biscuit-mounds. Similar features abound locally and worldwide, but their origins are not definitively known. Here they might have been formed by turbulence at the base of the flood waters flowing over the plateau, but sediment-trapping by plants or glacial suncups, segregation by freeze/thaw processes or earthquake vibrations, even digging by giant Pleistocene gophers have all been suggested as causes of these features where they’re found in different areas. But the origins of the mounds in the middle of the roundabout parking area are known. They were built by Oregon Dept. of Transportation to mimic those that cover the plateau.