10 Towering Facts About Giant Sequoias

What can grow as tall as a skyscraper and live for millennia? That would be the giant sequoia, one of the most impressive tree species on the planet. Here are 10 facts about America’s largest living residents.


The bark of a giant sequoia may be the thickest of any tree we know—on some specimens the outer layer of bark measures over two feet thick at the base. This formidable exterior provides the trees with super-powered protection. Their bark also doesn’t contain any flammable pitch or resin, and if it were to ignite in a forest fire, the girth would slow flames from reaching the wood inside.


Prescribed fire smoke at Sequoia National Park. Image credit: Daniel Mayer via Wikimedia Commons // CC BY 2.0

Giant sequoias not only can survive forest fires, they thrive on them. When a sequoia grove catches fire, the heat opens up cones on the forest floor and releases the seeds inside. The blaze eats up any brush or deadwood that’s accumulated on the ground while leaving behind nutrient-rich ash in which the saplings can flourish. Forest rangers only became aware of the renewing benefits of fire a few decades ago. Prior to that, they would extinguish every flame they saw then wonder why no new sequoias were growing. Today rangers will intentionally set controlled burns to simulate the natural process.



Fire isn’t the only threat a giant sequoia is built to endure. Thanks to a high concentration of tannin, an insoluble chemical compound found in many coniferous trees, the trees are immune to most diseases. Not only does the astringent substance protect the sequoia from fungus, it also safeguards it from insect attacks.


The largest tree on Earth is born from a very tiny seed—91,000 of them add up to a single pound. Giant sequoias can’t sprout from roots or stumps like the coast redwood can, which means all the reproductive responsibilities fall to the seeds. Animals like squirrels, chickarees, and beetles are instrumental in cracking open sequoia cones and dispersing the contents. But for a seed to germinate it needs to make direct contact with bare, mineral soil (which is why fires are so vital). Giant sequoias release 300,000 to 400,000 seeds per year, so there are plenty of chances for the conditions to be just right.


FlippinOats via Flickr // CC BY-NC-ND 2.0

Before the first Olympics were held or the first pyramids were built in Mexico, the oldest living sequoia had already started to grow. The President, located in California's Prairie Creek Redwoods State Park, is estimated to be about 3200 years old. Despite its old age, the giant hasn’t slowed down at all. The annual wood production of older sequoias is actually greater than that of younger specimens. And while three millennia may be more time than you can wrap your head around, it isn’t a record-breaker: Bristlecone pines and Alerce trees both live to be older than giant sequoias.


General Sherman. Image credit: Tuxyso via Wikimedia Commons // CC BY-SA 3.0

Giant sequoias don’t lay claim to the tallest tree on Earth (that distinction belongs to coast redwoods, a close relative), but they do have the largest tree by volume. General Sherman in California’s Sequoia National Park boasts a mass of 52,500 cubic feet, which is over half the volume of an Olympic-sized swimming pool. The trunk alone weighs about 1400 tons or the equivalent of 15 blue whales. According to the National Park Service, all that lumber could be used to build 120 average-sized homes.

As for whether or not General Sherman is the largest living thing on Earth, it depends on who you're asking. Under some definitions, the title belongs to the Great Barrier Reef or a 100-acre grove of Aspens in Utah that share a single root system. But if you limit the pool to single-trunked trees, the giant sequoia takes the cake.


Wikimedia Commons // Public Domain

European-Americans first stumbled upon giant sequoias in the foothills of the Sierra Nevada in 1853, according to The Guardian. The initial instinct of gold miners in the area was to chop one of the trees down, an act that took three weeks to complete. Once felled, a section of bark from “Mammoth Tree” was shipped to San Francisco for an exhibition. The bark was propped up to house a piano for performances before eventually ending up on Broadway in New York City. The following year, a second tree, dubbed “Mother of the Forest,” was toppled and its bark sent to the Crystal Palace in London. Meanwhile, the stump that Mammoth Tree left behind was used as a dance floor by flocks of tourists.

Not everyone was complacent to the destruction. In 1864, California senator John Conness urged Congress to pass a bill that would grant protection to Yosemite Valley and the neighboring sequoia grove. He argued:

“From the Calaveras grove some sections of a fallen tree were cut during and pending the great World's Fair that was held in London some years since…The purpose of this bill is to preserve one of these groves from devastation and injury. The necessity of taking early possession and care of these great wonders can easily be seen and understood.”

Once passed, that bill opened the door for the establishment of the first-ever national park at Yellowstone, and ultimately, America’s National Park Service.


Theodore Roosevelt standing beneath a giant sequoia in Mariposa Grove. Image credit: Houghton Library, Harvard University/American Museum of Natural History

An avid outdoorsman, Theodore Roosevelt was enchanted by the sequoias he saw out West. During a camping trip to Yosemite, his friend and fellow conservationist John Muir convinced the president to add the Mariposa Grove of Giant Sequoias to the park, thus granting the trees federal protection. Roosevelt said of the giants during a 1903 speech in Sacramento:

“As regards some of the trees, I want them preserved because they are the only things of their kind in the world. Lying out at night under those giant Sequoias was lying in a temple built by no hand of man, a temple grander than any human architect could by any possibility build, and I hope for the preservation of the groves of giant trees simply because it would be a shame to our civilization to let them disappear. They are monuments in themselves[…]”


Wikimedia Commons // Public Domain

Up until January 2017, one of the most intimate ways to experience a giant sequoia was by passing through one. Pioneer Cabin Tree in Calaveras Big Trees State Park had featured a tunnel big enough for a car to pass through since the late 19th century. The owner of the Calaveras North Grove carved out the opening to compete with a similar tree-tunnel attraction in Yosemite. For decades tourists were allowed to drive straight through it, but in recent years the only way to enter the tunnel was on foot. The tree fell to the ground and splintered apart on impact on January 8 during a severe rainstorm. Apparently the loss wasn't a total shock: The tree had been leaning for years, and prior to receiving its hole it had sustained a fire scar that kept the top from growing.


Giant sequoia in Catton Park, UK. Image credit: Rob Andrews via Flickr // CC BY 2.0

At one point giant sequoias flourished throughout the Northern Hemisphere, but their distribution has since become much more limited. Most sequoia trees are concentrated in 77 groves located throughout Northern California. A handful of specimens can be found elsewhere, thanks in part to horticultural trends of the 19th century. Exotic gardens were all the rage in England by the time the first sequoia was discovered by European-Americans in the 1850s. Today some of the oldest sequoias growing outside their natural range are housed in British castle gardens and arboretums. They can be spotted in other European countries as well: In France, the trees were once planted along entire streets.

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Sponsor Content: BarkBox
8 Common Dog Behaviors, Decoded
May 25, 2017
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Dogs are a lot more complicated than we give them credit for. As a result, sometimes things get lost in translation. We’ve yet to invent a dog-to-English translator, but there are certain behaviors you can learn to read in order to better understand what your dog is trying to tell you. The more tuned-in you are to your dog’s emotions, the better you’ll be able to respond—whether that means giving her some space or welcoming a wet, slobbery kiss. 

1. What you’ll see: Your dog is standing with his legs and body relaxed and tail low. His ears are up, but not pointed forward. His mouth is slightly open, he’s panting lightly, and his tongue is loose. His eyes? Soft or maybe slightly squinty from getting his smile on.

What it means: “Hey there, friend!” Your pup is in a calm, relaxed state. He’s open to mingling, which means you can feel comfortable letting friends say hi.

2. What you’ll see: Your dog is standing with her body leaning forward. Her ears are erect and angled forward—or have at least perked up if they’re floppy—and her mouth is closed. Her tail might be sticking out horizontally or sticking straight up and wagging slightly.

What it means: “Hark! Who goes there?!” Something caught your pup’s attention and now she’s on high alert, trying to discern whether or not the person, animal, or situation is a threat. She’ll likely stay on guard until she feels safe or becomes distracted.

3. What you’ll see: Your dog is standing, leaning slightly forward. His body and legs are tense, and his hackles—those hairs along his back and neck—are raised. His tail is stiff and twitching, not swooping playfully. His mouth is open, teeth are exposed, and he may be snarling, snapping, or barking excessively.

What it means: “Don’t mess with me!” This dog is asserting his social dominance and letting others know that he might attack if they don’t defer accordingly. A dog in this stance could be either offensively aggressive or defensively aggressive. If you encounter a dog in this state, play it safe and back away slowly without making eye contact.

4. What you’ll see: As another dog approaches, your dog lies down on his back with his tail tucked in between his legs. His paws are tucked in too, his ears are flat, and he isn’t making direct eye contact with the other dog standing over him.

What it means: “I come in peace!” Your pooch is displaying signs of submission to a more dominant dog, conveying total surrender to avoid physical confrontation. Other, less obvious, signs of submission include ears that are flattened back against the head, an avoidance of eye contact, a tongue flick, and bared teeth. Yup—a dog might bare his teeth while still being submissive, but they’ll likely be clenched together, the lips opened horizontally rather than curled up to show the front canines. A submissive dog will also slink backward or inward rather than forward, which would indicate more aggressive behavior.

5. What you’ll see: Your dog is crouching with her back hunched, tail tucked, and the corner of her mouth pulled back with lips slightly curled. Her shoulders, or hackles, are raised and her ears are flattened. She’s avoiding eye contact.

What it means: “I’m scared, but will fight you if I have to.” This dog’s fight or flight instincts have been activated. It’s best to keep your distance from a dog in this emotional state because she could attack if she feels cornered.

6. What you’ll see: You’re staring at your dog, holding eye contact. Your dog looks away from you, tentatively looks back, then looks away again. After some time, he licks his chops and yawns.

What it means: “I don’t know what’s going on and it’s weirding me out.” Your dog doesn’t know what to make of the situation, but rather than nipping or barking, he’ll stick to behaviors he knows are OK, like yawning, licking his chops, or shaking as if he’s wet. You’ll want to intervene by removing whatever it is causing him discomfort—such as an overly grabby child—and giving him some space to relax.

7. What you’ll see: Your dog has her front paws bent and lowered onto the ground with her rear in the air. Her body is relaxed, loose, and wiggly, and her tail is up and wagging from side to side. She might also let out a high-pitched or impatient bark.

What it means: “What’s the hold up? Let’s play!” This classic stance, known to dog trainers and behaviorists as “the play bow,” is a sign she’s ready to let the good times roll. Get ready for a round of fetch or tug of war, or for a good long outing at the dog park.

8. What you’ll see: You’ve just gotten home from work and your dog rushes over. He can’t stop wiggling his backside, and he may even lower himself into a giant stretch, like he’s doing yoga.

What it means: “OhmygoshImsohappytoseeyou I love you so much you’re my best friend foreverandeverandever!!!!” This one’s easy: Your pup is overjoyed his BFF is back. That big stretch is something dogs don’t pull out for just anyone; they save that for the people they truly love. Show him you feel the same way with a good belly rub and a handful of his favorite treats.

The best way to say “I love you” in dog? A monthly subscription to BarkBox. Your favorite pup will get a package filled with treats, toys, and other good stuff (and in return, you’ll probably get lots of sloppy kisses). Visit BarkBox to learn more.