On April 10–14, we rafted the Lower Owyhee River in easternmost Oregon with Ouzel Outfitters (https://www.oregonrafting.com/owyhee-river). Because this part of the river is not dammed, and the climate is arid, there is only enough flow for rafting during the earliest part of the season. The droughts of the past few years meant that most trips were cancelled, as ours was last year (2022). We had signed up for the second week of April, but there was only enough water for one trip during the first week of April. On the other hand, this year was exceptional. With all of the winter snow, flows are expected to continue for weeks. Ouzel has booked this year through May and might even have a trip during the first week of June. The river’s difficulty is classified as Class III.
Corridor of cataclysms
Kyle called the river a “corridor of cataclysms” because of the major geologic events that have impacted the river during the past 2 million years. The triad of cataclysms are (1) basalt flows that dammed the river for hundreds to thousands of years; (2) catastrophic emptying of glacial Lake Alvord when it topped its natural barrier and carried huge quantities of water and sediment into the river; (3) large-scale landslides that continue to cause large parts of the canyon walls to slump downwards toward the river, sometimes forming dams that block river flow.
Basalt flows. Four million years ago, before the river cut a canyon, basalt flows covered the region. Subsequently, the river began to cut downward and create an ever-deepening canyon. During this time, adjacent volcanic centers emitted numerous eruptions of fresh basaltic lava that flowed into the river and created natural dams that blocked the river’s flow and created lakes. The youngest eruption occurred just a few thousand years ago. Happily, the river is not currently blocked and visitors can marvel at the “cataclysmic” events that have impacted the river’s flow and shape.
Spilling of glacial Lake Alvord. Throughout the west many lakes formed as the climate was transitioning from the last glacial maximum ~18,000 years ago. There are some small remnants, such as Summer Lake in Oregon, but most of these areas are now dry desert. Alvord Lake occupied the area between Steens Mountain and the Owyhee River. About 13,000 years ago it topped its sill and large quantities of water and sediment flowed into the Owyhee River and blocked its flow for some time. We floated past the Crooked River (see map at top of page), which was the tributary by which the water and sediment entered the Owyhee River.
Landslides. Many places along the gorge are crumbled and chaotic because of landsliding. Parts of the canyon walls are rotational blocks that have moved downhill along slide planes.
Other river images
Native American art
Native Americans lived in this region for 1000s of years before European settlers disrupted their way of life. On Day 3, we stopped at the Hole in the Ground location to view petroglyphs scratched into the basaltic rock by native people. The patina is desert varnish, a thin red-to-black coating found on exposed rock surfaces in arid regions. The varnish is composed of clay minerals, and oxides and hydroxides of manganese and iron.
We were happy to experience the Owyhee River with unusually high-flow conditions, although the cold temperatures were a challenge. We’d like to go again, in lower-flow conditions, when the trip would be more leisurely, with more time for hiking. Taking photographs was difficult when on the water, and I lost my water-proof camera to the river on Day 2. At least I still had my phone! Thanks to Jay and Ann for contributing their photos.
And thanks to the U.S. Geological Survey (USGS) for funding Kyle to study this fantastically interesting part of the country. The USGS is chronically underfunded, which in my view is short-sighted, given how important it is for us to understand how our planet works.