Hawaiian islands formation | Cosmology & Astronomy | Khan Academy

[@grreeknick]

So I'm both a geologist and an educator, and I found this explanation just as clear and as precise as it could possibly be. Great work, Sal!

[@BoydIt-cw8uc]

This is great, thanks Khan Academy!

[@wlohNiCK]

Thank you so much! Got A-Level exam tomorrow all about the causes of tectonic activities. As well as plate boundaries i gotta talk about hotspots. This video answered every single question i have had about hotspots. you've helped me out! :D

[@matthewcabrera9338]

Was anyone else's mind blown?

[@papadehmer1893]

Yes I did enjoy your explanation you made it very easy to understand Mahalo!!

[@leilehuayuen3794]

Great explanation! Mahalo (thank you) for making this available. I will share it with my hula students. One way to differentiate between the island and the state is to call the state "Hawaiʻi Nei" and the island "Moku Hawaiʻi." ❤️

[@manoftheleaf]

6:08 Mauna Kea is the name of the mountain you are mentioning. Loihi is the name of the next underwater mountain to break the surface of the pacific ocean long after most of us are dead. So indeed the hot spot has indeed shifted and the volcanic activity in Kilauea and Manua Loa has been minimal. In the past Ancient Hawaiians believed that The big island was the oldest island and that the goddess Pele moved from Tahiti to Hawaii. Hawaiian Pride!!!

[@monkfish2047]

Wow. thanks for the helpful information on kawaii.

[@Pyrolonn]

While erosion would make the mountains smaller the main reason is the old islands are actually sinking back into the ocean. (Keep in mind they how massive they are, they will always be fighting gravity to keep their lofty heights) This is a bit esoteric but the hot spot that causes the Hawaiian islands may have been caused by an antipodal meteor strike (that is a strike on the opposite side of the Earth)

[@theranova99]

The islands are eroding down at about I mm per year. Do the math and you'll see how thousands of meters of rock are lowered over a few million years.

[@Ninjastripy]

Maui, Lanai, Molokai, and Kahoolawe all used to be 1 big island. So maybe in the future the Big Island will be several smaller islands, too.

[@3seven5seven1nine9]

Dang that hotspot's been there for an unbelievably long time

[@prettybadusername]

A hot spot is when it reaches the surface. All the time its under the surface its a mantle plume

[@Crazy4Collins]

Thank You.

[@ninarocks5031]

Sooo helpful for my project!!

[@phonic0photon]

Subduction is still speculative science, even still I appreciate the shared observations.

[@Yojimbokun]

lol wow

[@m3l0dycute]

the book confusse me alot but your video is much easier to understand

[@lllMrKrobylll]

Nice video! Thanks!

[@tetsushatarii2108]

It’s fascinating that the tectonic plate shifted direction. Surprised it didn’t get mentioned in the video.

[@hedonism13]

Is this part of the cosmology & astronomy playlist or a new geography playlist?

[@NoRefundsXD]

Thank you very much! Khan Academy rules!

[@deadman12078]

The hot spot the creates the islands also pushes the earths crust up so as the Islands move away from the hot spot they drop into the ocean.

[@theranova99]

Not really. The weight of the islands caused a downward indentation in the ocean floor. As the islands erode away, this indentation reverses upward.

[@quentinpearson9910]

Great video! Very informative!

[@makenaridiros2481]

this was so so helpful

[@bigislechicka]

Very helpful when you can't understand what your geography book is trying to explain ..... :0)

[@prettybadusername]

Great video

[@riley8478]

hi

[@jeremybanks8262]

Hi

[@carina_t]

hi

[@thatgnaralooguy]

good observation. that's what appears to have happened.

[@annsdailybasis]

I always hated science but for some reason i like it now after this video

[@RosalezJohn]

Very interesting. Nice video

[@jadynhope]

0:52 I SAW THE VOLCANOES ERUPT WHEN I WAS THERE!!!!!!!! we r going AGAIN this christmas...it'l be my 11th time...blech i hate the long airplane rides....

[@rhz5802]

Heres something crazy! Humans existed earlier than the big island. If its 700k years ago then humans were in the paleolithic age, or around the time we stopped living in caves and started building more permanent settlements. Or around 900k years ago

[@deadman12078]

I have a theory... The continents are actually the remnant of when Thea hit the Earth. Is it all that crazy? Why else would there be one huge mass then break apart into the continents we know today?

[@Kortugal]

sal what do you do by proffesion you teach calculus and geology?

[@shaimaagamal4468]

very nice

[@marcielynn4886]

Its the hot spot that the islands have all crossed over.

[@Haradin32]

will loihi be part of america when it comes up?

[@Mekratrig]

Hokay, good esxplanation, but it doesn’t go far enough. Whyy does the string of undersea eroded mountains make a sharp turn to the north?

[@mr.handsomeboy8829]

Mekratrig plate tectonic was moving that direction .

[@Salvor_Hardin_42]

Convection + Basalt is more dense than Granite.

[@hummingpylon]

So the mantle must be pretty liquid if we talk about convection

[@flawnJr]

very well explained. but i've been finding it difficult to follow ur cursor. its small and not so clear.

[@theranova99]

Not bad. Geologists no ,longer believe that hot spots do not move. The bend in the chain of islands is possibly due to the hot spot moving south about 45 million years ago.

[@swinde]

The Hot spot does NOT "move" south. The Entire Pacific plate is moving northwest.

[@michaelstanley1974]

Fabulous

[@MrAartJansen]

How do you tell the age of the volcanic rock? I mean it's magma for probably millions of years, it cools to become a rock, but is essentially made up of the same carbon / elements just colder/solid now. Once lava turns to rock what is the change that makes you able to tell its age ?

[@theranova99]

That's fairly easy. Carbon dating is not usually used for lava, but more than 10 independent methods, including K-Ar. The results are cross-correlated and are remarkably consistent, showing very recent lava to several million years. On my island (Oahu) there is a lava flow only 6,000 years old, but other volcanoes here are 1-3 million years

[@aviralverma5393]

HELLO ANSWER WHY ARE HOT SPOTS LOCATED FAR FROM TECTONIC BOUNDARIES

[@theranova99]

Actually some hotspots are in fact located at plate boundaries, others along mid-ocean ridges, some in the middle of plates. The question is, is it random? Or is the crust sufficiently penetrable at some places? See pubs.usgs.gov/gip/dynamic/world_map.html

[@gennybaker91]

Since the hotspots are stationary, what is the reasoning behind the bend above the hawaiian islands? Did the plate shift?

[@theranova99]

See my answer above.

[@janakiramnallamothu3020]

Is this explanation applicable to all island archipelago's on earth which are formed by Plate Tectonics?

[@slashwalkerable]

@khanacademy: GREAT VID, MATE! Hey, could I somehow get your contacts, please? I'm a junior geologist and sometimes I find it dificult understanding things... But I really love the science, so I'd like to complete my course and graduate... So.. if that wouldn't be that difficult, could you sometimes simply explain those to me. You talk human language, and my lecturer does not... -.-

[@jadynhope]

@AUTubeN22 There were different types of lava. The fast flowing lava was called pahoehoe and was more smooth. When pahoehoe hit a bump (like a rock) it created crazy shapes.

[@DoctorSparklesMusic]

...or, if the earth is growing (see Neal Adam's growing earth models), the hotspot appears to move relative to other landmasses (from the end of the Aleutians to present location) due to global expansion. ;)

[@micahmashima2195]

what are the 8 stages of island development

[@QuantumBraced]

Hm, so what this means is that eventually Honolulu will sink, correct?

[@theranova99]

Yes, but not while Im still living here!

[@jadynhope]

Sal, Hawaii is pronounced ha-wa-ee, not ha-why-ee. Or, if you want to get really close, the natives pronounce it ha-va-ee. Just thought this would be a cool fact...

[@solomonherskowitz]

It is

[@IslandAtheist]

Theory or hypothesis?

[@theranova99]

Its a comprehensive theory that has been partly validated.

[@annieharford8550]

the island is in the Magna vain

[@nickwancho]

The cursor is next to impossible to see when using it as a pointer

[@32simas]

moore geo!

[@taseletasele4886]

lemuria is a lost continent under polynesia

[@georgehinckle2028]

what happens when the hot spot goes around the earth a bunch of times in the next 5 billion years or so. is there going to be a big ol ring around the planet or what.

[@judsonwall8615]

If you look at the very top of the chain, you’ll notice that the last underwater seamounts are close to the trench next to the Aleutian island chain of Alaska. That trench swallows (subducts) the oceanic crust. Eventually, the entire island chain that’s visible today will be swallowed by this trench. The trench has likely subducted several older islands/seamounts already.

[@gauravyadavraosabh8369]

Hindi me

[@Vaderoid]

@adkinsjr NephilimFree is a liar.