January 13, 2025 – A Note From Shasta Indian Nation: Trails are being developed that will be available for public use. We ask all parties to use sites and facilities when they’re ready and not before. There will be opportunities for hikers but they will be on trails that are designed to protect historic and cultural sites. For additional information, please contact culture@shastaindiannation.org.

COLUMNAR BASALT ON THE KLAMATH RIVER

In the Kickacéki Reach (Ward’s Canyon) of the New Klamath, rafters and kayakers are treated to the captivating cliff formations of the Copco Basalt. You’ll see elegant forms of what are, or at least appear to be, nearly geometrically perfect hexagonal columns of rock, nested together in a sort of tectonic honeycomb. Indeed, this type of formation is known around the world as Columnar Basalt and the intricacies of the rocks alone make for popular tourist attractions. Well-traveled rafters may recognize the forms from Devils Postpile National Monument near Mammoth California, Devil’s Tower, Wyoming, or the Columbia River Gorge east of Portland Oregon. Other famous occurrences of columnar basalt around the world include numerous locales in Iceland, the Garni Gorge in Armenia, Giant’s Causeway in Ireland, the Hexagons River in Israel, or the Linga Columns in India, just to name a few. The Copco Basalt Columns in Kickacéki Reach have been seen by far fewer eyes due to the dewatering of the river since 1925 (completion of Copco 2 Dam). Though worlds apart, each of these iconic cliffs share a common thread in the story of their formation.

Columnar basalt wall in Kickacéki Reach (Ward’s Canyon) of the Klamath River. Photo by Will Volpert.

Understanding and visualizing the formation of these spectacular columns requires something of a mental reset and geologically zooming out. In the greater context of geologic time, the Copco Basalt is very young, even by volcanic rock standards. It has formed incrementally over the last 140,000 years, with some basalt flows less than 2,000 years old. That was prior to the last ice age. No dinosaurs, but we did have mammoths. On a large scale, the planet looked much like it does today. The major mountain ranges were formed. The Grand Canyon had been incised. Mammals were the dominant creatures on Earth. But on a smaller scale of hills and valleys, the landscape looked quite different and local rivers and streams may have taken different courses. Salmon still swam up them to spawn. Although the Klamath River itself approximately followed the same course as today. The Klamath River is actually older than the Cascade Mountains themselves. The landscape where the Copco Basalt formed was likely still somewhat of a canyon, but a canyon surrounded by fire.

Joints is a word geologists use to refer to natural cracks in the rock because they tell us a lot about the structural history (and impact construction potential). Columnar jointing in rocks is almost universally associated with only one type of rock: Basalt. That distinction has to do with the unique properties of basalt. Basalt is a volcanic rock. That is to say it forms directly from lava, or molten (liquid) rock that is erupted on the surface, typically from volcanoes or vents at the surface. In modern times, basaltic lava is erupted regularly from the volcanoes in Hawaii, Iceland, and Ethiopia. The volcanoes with high summits such as the Cascades (including nearby Mount Shasta), Chilean Andes, and the Philippines feature a different chemical composition that fosters viscous lava and powerful, dramatic, and explosive eruptions sending ash into the stratosphere. Think Saint Helens 1980, Pinatubo 1991, or Hunga Tonga 2022. By contrast, basaltic eruptions are more docile flows of fluid, glowing lava that invite sightseers. These are the sorts of eruptions that occurred in the Klamath Canyon over the last 140,000 years

Gazing up at the gracefully arching and twisting forms of the Copco Basalt and thinking of lava conjures imaginative visions of flowing rock. However, you’re deceived by your desire to see the past landscape unchanged from today. When flowing lava cools, it splits and cracks into all manner of jagged edges and forms a miserable surface to travel on. Go to Craters of the Moon National Monument in Idaho if you need proof. Columnar jointing in basalt is formed by the opposite of flowing lava: stagnant lava. The columns are formed not by crystal growth, but by cooling contractions. Here’s how that works.

The formation first requires an enormous volume of lava to be released in a relatively short time. The lava may flow just like a slow-motion mudslide or avalanche, following gravity downhill into a valley. At the downstream edge of the flow, the lava will somewhere cool and harden to rock and form a dam, trapping the rest of the lava upstream in a massive, 2000 degree hot tub. As lava cools, it solidifies into rock. This is where we get technical, but not much more so than 10th grade geometry. Solid rock is more dense than liquid rock (true for just about any compound EXCEPT water) so it shrinks as it cools. Somehow, as it shrinks, it must take up less space. That space is created in the form of joints.

Ward's Canyon Klamath River

Columnar basalt in the Kickacéki Reach (Ward’s Canyon) of the Klamath River. Photo by Will Volpert.

The figure below illustrates how this works. The cooling process is generally uniform across the top surface of the lake. As the lava cools and forms more dense rock, tensional forces build up across the entire molten lake surface like plastic wrap over a salad bowl. Eventually, the tension exceeds the strength of the surface and a joint will form. This joint releases energy and establishes two cooling centers on either side where the tension was released. As the joint propagates across the surface, it wants to split and release more tension. When it splits, it does so at a 120-degree angle so that all three joints are equiangular from each other. Once the splitting starts to occur, specific cooling centers are established that form the center of each hexagonal column. The cooling centers each naturally pursue balance and equilibrium by establishing additional tension joints in all directions. This drives a chain reaction across the surface of the lava flow and carves out apparently perfect hexagons.

Lamur, A., Lavallée, Y., Iddon, F.E., Hornby, A.J., Kendrick, J.E., von Aulock, F.W., Wadsworth, F.B., 2018. Disclosing the temperature of columnar jointing in lavas. Nat Commun 9, 1432. https://doi.org/10.1038/s41467-018-03842-4

I say “apparently perfect” because upon closer inspection you might find plenty of off-kilter shapes like pentagons and heptagons. But sometimes nature does a pretty remarkable job with its geometry. Much like how bees build hexagonal honeycombs to conserve building materials, lava forms hexagonal columns to minimize the total amount of jointing it has to endure. Next time you wash a glass in the sink, take a moment to look at the suds on the outside of the glass through the glass itself. You’ll see hexagons.

The cooling rate at the surface of the lava lake defines the size of the columns. If cooling happens quickly, more joints develop and the columns are more stringy and narrow. If the cooling happens gradually, the joints have more time to grow before splitting and thereby carve out larger hexagons. But so far we’ve just talked about the hexagons, the joints, and the surface. How does that translate into columns?

Basalt Ward's Canyon

Columnar basalt dwarfs a Black Bear in Kickacéki Reach of the Klamath River. Photo by Will Volpert.

After the top surface has cooled and hardened, there’s still plenty of hot lava below with lots of heat to release. How tall are some of those columns? One hundred feet? Imagine a lake over 100 feet deep of lava! That top surface starts to become somewhat of an insulating layer and makes the lower levels cool more slowly. But the joints are already defined from that initial surface tension and cooling centers. The joints themselves become the primary pathways by which heat escapes. In fact, the very top surface is often much more disturbed and broken up. The columns really start to take shape a little deeper in the flow. As cooling continues, the joints propagate downwards. Now for the final technical bit of more complex geometry: The joints will always grow perpendicular to the cooling surface. Not the top surface, but an imaginary surface where the melting/freezing point of the lava is reached. So what happens if, say, some water were to flow over one narrow streak of this lava lake? Lots of sizzling and steam, sure. But that sizzling and steam means faster heat release and faster cooling and faster joint propagation just along that narrow streak. So now, the imaginary cooling surface has moved down through the lava faster and further in that spot. Like a french press screen going down but being pushed down further in one spot by an extra rod. Or a trampoline with three kids on it. So now the cooling surface is warped and curved. Recall that the joints form perpendicular to the cooling surface. If the cooling surface is curving erratically, the columns will as well.

In the case of the Copco Basalt, there is a long legacy of lava flows damming the river entirely and forming lakes, which eventually overtop the volcanic dams and cut back to a typical channel over hundreds or thousands of years. The most recent lava dam formed in this reach within the last 2,000 years just downstream of the former Copco 1 Dam site and has since been eroded.

When we see the sinuous columns formed above the river in Kickacéki Reach, we infer several things about the landscape before humans. The valley was somewhat flat, though confined enough to hold a deep lake of lava. Volcanic vents nearby supplied enough molten rock to fill the lake and let it stagnate long enough to form enormous elongate columns. An ancient water supply, perhaps the prehistoric Klamath River or smaller creeks, flowed through the joints and created sweeping curves in the columns. While similar formations have inspired awe all over the world, columnar basalt is actually not actively forming anywhere today. So perhaps the origins of these rocks align with scientific conjecture, or perhaps they were indeed the handiwork of crafty titans before our time.

ADDITIONAL INFORMATION ABOUT THE “NEW KLAMATH”

SOURCES

Hammond, P.E., 1983. Volcanic Formations Along the Klamath River Near Copco Lake. California Geology, v. 36. P. 98-109. California Division of Mines and Geology. Sacramento, California.

Lamur, A., Lavallée, Y., Iddon, F.E., Hornby, A.J., Kendrick, J.E., von Aulock, F.W., Wadsworth, F.B., 2018. Disclosing the temperature of columnar jointing in lavas. Nat Commun 9, 1432. https://doi.org/10.1038/s41467-018-03842-4

Wikipedia. List of Places with columnar jointed volcanics. Accessed Jan 8 2024.

Williams, Howl and Masson, Peter. 1949. Geology of the Macdoel Quadrangle. California Dept. of Natural Resources. San Francisco.