Geologist Dr. Bob Carson explains the ancient origins of the Klamath Mountain Province from a gravel bar deep in the Kalmiopsis Wilderness, along the wildest part of the Oregon’s Wild and Scenic Illinois River
Ever wonder about the geology of the rugged southwestern-most corner of Southwest Oregon—aka the Kalmiopsis Wildlands? In the short video below—filmed by Zach Collier on a gravel bar on the National Wild and Scenic Illinois River — Bob Carson, Phillips Professor of Geology & Environmental Studies, Emeritus at Whitman College, explains the ancient origins of the Klamath Mountains and the Kalmiopsis Wildlands,
This fascinating, short geology lesson is even more relevant now that it was when filmed in 2019. This is because Senators Wyden and Merkley just introduced a visionary piece of legislation called the River Democracy Act of 2021, It includes protections for many tributaries of the National Wild and Scenic Illinois, North Fork Smith and Chetco rivers—i.e. the rivers of the Kalmiopsis. But stay tuned for more on the River Democracy Act another time.
First a little context for Dr. Carson’s wilderness geology lesson
The Kalmiopsis is a subrange of the Klamath Mountain Province. The latter spans southwest Oregon and northwest California. The Kalmiopsis lies between a narrow extension of the California Coast Range in the west and the Siskiyou Mountains in the east. The Siskiyou are another subrange of the greater Klamath Mountain Province, aka, the Klamath-Siskiyou Ecoregion. Note – It could also be argued that the Kalmiopsis are a subrange of the Siskiyou Mountains
Flowing through the Kalmiopsis are the National Wild and Scenic Illinois, Chetco and North Fork Smith rivers, plus five U.S. Forest Service Eligible Wild and Scenic Rivers—Baldface, Rough and Ready, Josephine/Canyon, Silver and Indigo creeks. It is literally a wilderness of rivers.
While part of the Klamath-Siskiyou Ecoregion, the Kalmiopsis is more rugged in general and geologically unique in its own right. At its wild heart is the congressionally protected 179,000 acre Kalmiopsis Wilderness. It’s surrounded by the North and South Kalmiopsis Roadless Areas and smaller nearly roadless areas—this is the largest unprotected National Forest wilderness in Oregon and the only place like it on the West Coast, south of the Olympic Peninsula.
Dr. Carson is on a four day rafting trip down the Wild section of the National Wild and Scenic Illinois River. They’re deep in the Kalmiopsis Wilderness on one of the most inaccessible stretches of river in the nation. I’ve rowed the Illinois a few times myself many years ago. I can only say, for me personally, it was life changing.
Carson describes the diversity of rock and landforms he observed as he traveled down the river with Zach Collier. He begins by explaining that there are numerous subranges within the Klamath Mountains and that the whole was formed by at least five different bodies of rock slamming into the North American continent.
Watch | Geology of the Kalmiopsis Explained.
Here’s a partial transcript from Dr. Carson’s riverside explainer about the geology and ancient origins of the Kalmiopsis Wildlands:
The thing that’s particularly interesting about the geology of the Klamath Mountains is that you have at least five bodies of rock called terranes that were accreted, were added to, North America over the recent hundreds of millions of years. Their fossils do not match those of North America. They have more affinity to Asian critters and their latitude that we can determine by paleomagnetism is much closer to the Equator than we are now
So these bodies of rock have come and slammed against North America and there’s quite a variety. Some were oceanic crust. Some were continental fragments. Some were island arcs like the Aleutians, some of them were perhaps shield volcanos … the variation in the rocks that came here was great to start with—it may have been volcanos and reefs and ocean floor sediments and ocean basaltic crusts—but once they got here, and they came in at least five packages, they were partially subducted beneath North America—just like the Cascadia subduction zone is doing to the Juan de Fuca Plate today—and depending on how deep they went they had different degrees of metamorphism. In some cases they went deep enough to melt, which made igneous bodies like granite within this bunch of rocks.
So as we go down the river we see a huge variation in the outcrops of rocks, all of which have been fairly severely deformed … so on every gravel bar, like the one I’m sitting on now, there’s a huge variety of rocks.
There’s an extreme diversion in the igneous rocks, plus there’s quite a bit of difference in the metamorphic rock … not only did the igneous and metamorphic rock have great variety but so did the sedimentary rock. There’s evidence of in some of the rocks we looked they from the deep ocean floor …
The whitewater here is spectacular. It just never stops … there have been lots of landslide and rockfalls into the river which makes it narrow and constricts it … There’s places where the river goes through gorges, where the water may be still, as in still water runs deep. But there’s also good whitewater where there are alluvial fans when debris flows have come down tributary streams during heavy rainfall events.
There’s some landforms here that are world class. I’ll try to just mention one and that is potholes. Potholes occur when a swirling current sweeps around boulders and drills a cylindrical hole in the rocks. We found one pothole that was three meters in diameter and had boulders up to one meter in diameter inside it.
So in summary this river has spectacular scenery, a huge variety of vegetation, alternating glider valleys and canyons but above all there is almost every kind of rock that you think of … Let’s protect the Illinois River Area even more, let’s continue to protect the Kalmiopsis Wilderness Area and let’s protect more and more of the whole Klamath Mountain region. Let’s conserve. Let’s preserve. Let’s enjoy.
Journey through time and geology along the Wild and Scenic Illinois River
The National Wild and Scenic Illinois River begins with the 17 miles long Scenic River Area just outside of southwest Oregon’s Illinois River Valley after the East and West Forks of the rivercome together.
At the Siskiyou National Forest boundary, the Illinois River gradually drops into a deep river canyon that flows between Roadless and unroaded areas. These include the South Kalmiopsis Roadless Area, the North Kalmiopsis Roadless Area, and the _______ Mountain Roadless Area, and the Six Mile and Rancheria Creeks unroaded areas.
As it leaves civilization, the river’s watershed is penetrated primarily by two road systems that end at the Kalmiopsis Wilderness. One—FS Road 4201— takes you through the stark serpentine terrain of the Eight Dollar Mountain Botanical Area, with its Jeffrey pine savannas and serpentine Darlingtonia wetlands. The road is designated the T.J. Howell Botanical Drive and eventually arrives high on the watershed divide between the Wild and Scenic Chetco and Illinois rivers and access to the Kalmiopsis Rim trail which goes both north and south.
The other—FS Road 4103—is known locally as the Illinois River Road. It travels down the scenic river canyon of the Illinois and past the developed Six Mile, River Bench and Store Gulch recreation sites. Along the way are views of the river and Pearsoll Peak. At 5,098 feet, it’s the highest point in the Kalmiopsis.
Pay close attention on both roads and you will see, exposed in the rock (and the soils formed from it) evidence of the ancient epic forces that shaped the Kalmiopsis Wildlands. This is made more visible by the often abrupt changes in vegetation. Download USFS T.J. Howell guide here.
At Briggs Creek, rafting the Illinois River gets to be serious business (if not before). As it flows through the Kalmiopsis Wilderness, the Illinois River Trail provides to only land access to the river at Pine Flat. Otherwise there is no way out of the Illinois’s Wild River Canyon except on the river itself. In this reach, large tributaries, like Silver, Indigo and Lawson creeks flow out of the North Kalmiopsis Roadless Area.
The Wild Section of the National Wild and Scenic Illinois River flows through the Kalmiopsis Wilderness for nearly 28 miles—between the confluence of Briggs Creek and Nancy Creek. There’s 150 rapids, 11 of which are Class IV and one which has af Class V difficulty rating. Here, the Illinois is one of the most inaccessible sections of wild river in the nation, and should only be run by highly skilled and experienced boaters.
It joins the world famous Rogue River just below the community of Agness. The photo below shows the stark difference in the water quality and clarity between the Illinois (in the foreground) and the Rogue River. The photo also indicates the importance of the Illinois River’s contribution to the water quality and quantity of the lessor known Illinois River and also of its native salmon and steelhead runs that are primarily caught in the lower Rogue. Read more on Native Fish Society’s Illinois River page.
Snapshots from one of the remotest and geologically complex river canyons in the nation
A word about Indian Rhubarb (aka umbrella plant)
You won’t see Indian Rhubarb, Darmera peltata, growing just anywhere. In its native habitat, it’s found primarily from southwest Oregon into northwest California and the central Sierras. On the Wild and Scenic Illinois, you will see the first signs of it along stream banks in the spring, It emerges leafless from rhizomes that are underwater but not underground.
- Yosemite National Park on Indian Rhubarb
- Darmera peltata, Plants For A Future
- Darmera peltata, The Jepson Herbarium
A word about radiolarian chert
Dr. Carson mentions radiolarian chert. Here’s more information about radiolarian chert from the National Park Service and the Golden Gate National Recreation Area. You can observe it on the Wild and Scenic Illinois and Chetco rivers and I’m guessing elsewhere in the Kalmiopsis.
More about the National Wild and Scenic Illinois River
- National Wild and Scenic Illinois River.gov
- Illinois River: Oregon’s wildest and most remote stream, Zach Urness, Salem Statesman Journal, Feb. 15, 2017
- Illinois River – Rogue River-Siskiyou National Forest
- Oregon’s National Wild and Scenic Illinois River
- The Illinois River Basin
- Illinois River, The Native Fish Society
- Oregon Wild and Scenic Illinois River
- Southern Oregon needs its Wild and Scenic Rivers, Tim Palmer, Medford Mail Tribune, April 15, 2018
- Senator Wyden proposes Illinois Valley Salmon and Botanical Area
- Wild and Scenic Illinois River protected from mining