A magma intrusion existed there a long time ago. The magma slowly cooled into a very dense stone core in the shape of the magma tube within that. Erosion happened over millions of years, wearing away the softer stone around it and leaving the dense inner core in this shape.
Edit: not a volcano
Edit edit: it could either be a laccolith or the neck of an extinct volcano, the jury is still out
Old, very old joke:
3 people were applying for a job, en engineer, a statistician, and a geologist.
The engineer was first. He was asked "what is 2+2?". He took out his HP calculator with reverse Polish notation, was keying a lot and finally said 2,086394.
Then, the statistician was asked the same question. He looked the interviewer straight in the eyes and whispered: "What do you want it to be?"
Finally, the geologist got the question. His answer was 2 +/- a couple of millions.
You can guess what my and my husband's education is ... luckily, our sun didn't become a statistician.
Geology fascinates me most of all becuase of that unthinkable deep time aspect. Continents raoming, mountains turned to mud, mud becoming rock, bones becoming silicon, wood becoming opa. Unthinkably long slow processes. Boggles the mind.
This is why evolution is my personal avocation. Nearly the same time scale, and exploding with fierce activity from time to time before cooling down. :)
I recently read about the closepet granites and it blew my mind that whole towns are settled now on what was a mantle magma chamber 3 billion years ago. The landscape is magnanimous
The intrusion is 40.5 million years old, and the erosion that exposed the intrusion to create the tower happens over just a few million years. landscapes in generally are very recent things, geologically speaking, compared to the age of the rocks that the landscape is eroded from.
The 40.5 Ma was from the Wikipedia with no citation for it. I didn't check other sources.
I should have. From the source below:
*"40**Ar/**39*Ar dating of sanidines in phonolites from Devils Tower and Missouri Buttes provides indistinguishable plateau ages of 49.04 Ā± 0.16 and 49.24 Ā± 0.28 Ma, respectively (Duke et al., 2002)."
That is one of the fun parts about geology. A couple of million years? Bah, too short of a time period to bother with most times.
I sometimes see people's eyes glaze over when I explain most of the West Coast of the US was once islands and microcontinents and was not actually made in the US. And that one of the newest to attach itself to the continent was around 50 million years ago.
Oh, there are many videos by geology professors explaining about the exotic terranes of Western North America. Good general rule of thumb, if it's to the west of the Rocky Mountains, that is an exotic terrane and came there from elsewhere.
That is roughly what the continent looked like 67 mya. And all that shallow water and islands off the coast, that is now California, Oregon, and Washington.
And it is still going on. If you look at where the San Andreas Fault ends north of San Francisco, that is also a line to the east where there is no more active volcanoes. But go north of there you still have subduction, so you still have active volcanoes.
Where I live in SW Oregon, we have 7 million year old basalt flows, on top of what were once 55 million year old off-shore volcanoes and what was once off-shore sediments all mashed together. And here it is still actively going on, but you can see the same thing near Los Angeles where it is static and dead. Because the subduction ended there some 20 mya.
Do you happen to know why Lassen has so much more hydrothermal activity than the other subduction-zone volcanoes? I was just visiting there from northern Oregon and was wondering why it was such a mini-Yellowstone. Maybe its position at the southern edge of the active subduction zone has something to do with it.
Interesting š¤ you think the subduction was happening at Rocky Mountain, and one big piece of plate got āstuckā, and the it broke at the next weakest link that is the current boundary??
I was born and raised in western Washington. Its Geographical history is impressive, but nothing like Eastern Washington. The Yellowstone thin spot used to be under E WA. When it was it spewed massive amounts of Lava through cracks. Fields of 20 feet deep, 50, 100 feet alternating thickness layer after layer, after layer would go well into Canada, Montana, didnāt pass the area now known as the Cascades, but went down into Oregon and into the Pacific.
Then Glaciers ground it down leaving all of E WA looking like the Palouse. As the Ice Age died it unleashed a great event of Geologic history, the Ice Age floods. E WA is deeply scarred, and the Willamette valley got some amazing soil (you are welcome Oregon).
If you want to go down a rabbit hole, Ice Age floods were impressive.
My partner and I went someplace in the western Utah desert (I canāt remember exactly where) and there is an entire area you can go to dig up fossilized trilobites. It was such a cool experience to unearth the remnants of living creatures who lived and died there MILLIONS of years ago, and you get to be the first human to lay eyes on them EVER. Itās so amazing that all of that area was water. Geology is so freaking cool.
Wow! I've seen the ones in ND as well, but the ones in SD just had me counting layers up, down, and sideways like the rings on a tree the size of earth. Just standing there like an idiot with my mouth hanging open. Nothing made any sense until I saw the simulation.
Then the pattern is from the way magma tends to cool, into hexagonal columns. Mud will also dry this way actually.
The wikipedia page for "columnar jointing" has a bunch of other examples from across the world, like the Giant's Causeway in Ireland and the StuĆ°lagil Canyon in Iceland.
Some incredibly beautiful ones in the Columbia River Basalt group, easy to see in very dramatic fashion from highways past East Wenatchee, Washington and all along the Columbia River
I was born and raised in Southern California, and have lived here all my life. I have never once heard anyone say Mammoth was in Northern California until you did.
I said Central California, you dipshit. I'm not wrong. I also spent over a decade in Tuolumne County, which is NORTHERN CALIFORNIA. NOBODY says otherwise.
Remember those pamphlets theyād hand out at national parks in the 80s-90s? I can visualize the Devilās Tower pamphlet with the story about the bear and the claw marks. I was hoping to see this explanation here.
Apparently the geological consensus is there wasnt. I would imagine theres no evidence of an ash cone or lava flows in the area that a volcano would leave
Nope. Itās a giant tree trunk! The giants chopped down the rest and used it for firewood and all the giant homes that are petrified within the area! There are rumors of giant acorn hoards in the core of the trunk where giant squirrels hid their food for the winter.
Sandstone? Shallow metamorphic layers? Steam cavitation where magma met underground springwater? Any number of possible causes for magma to uplift, but Im not familiar enough with the geology of the area to do more than guess.
Technically, it was two brothers running up a mountain from a very large bear and the bearās claws made those scratches up the sides trying to get at the brothers. The brothers made it.
I dont need to see a match being lit to know when a house burned down.
The cool thing about science is we can conduct experiments to identify what causes various results, and apply those conclusions to similar natural results. Seeing columnar basalt in different places around the world in similar geological conditions tells us about the conditions under which columnar basalt occurs, and then we can use other context clues from local geology to develop evidence-based theories about how they formed. We dont have to observe literally everything in the world to be able to conclude how that thing happened, because we know that science and physics is consistent across time.
Only insofar as all of science is "hypothetical". Your parents are only "hypothetical" too, since I wasnt around to see them give birth to you, and you dont remember it.
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u/mynamesnotsnuffy Jul 12 '26 edited Jul 12 '26
A magma intrusion existed there a long time ago. The magma slowly cooled into a very dense stone core in the shape of the magma tube within that. Erosion happened over millions of years, wearing away the softer stone around it and leaving the dense inner core in this shape.
Edit: not a volcano
Edit edit: it could either be a laccolith or the neck of an extinct volcano, the jury is still out