The Cascadia Subduction zone is a plate boundary that stretches from Vancouver to Northern California, and has the potential to kills thousands of people and destroy cities if it produces a major earthquake. Despite the risk, communities and governments have done little to prepare. en.wikipedia.org/wiki/Cas…
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📅︎ Jun 06 2020
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ELI5: Why can't we dispose of nuclear waste by putting on a subduction tectonic plate to sink it into the earth's core?

I saw the John Oliver segment on nuclear waste, and thought of the following idea:

Bury the nuclear waste on the subducting side of a subduction boundary of tectonic plates, near the actual boundary. Eventually the tectonic plate, along with the nuclear waste buried in it, would sink under the continental crust where it will melt, become super hot magma, and I assume be diluted in the various super-hot elements down there and gone forever.

Would this work? Or am I missing something?

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👤︎ u/oneMadRssn
📅︎ Aug 24 2017
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Difference in Volcanic explosivity index?

Is there a difference in the VEI of a volcano found on a divergent or subduction boundary? Why is this?

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📰︎ r/geography
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📅︎ Sep 16 2015
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How could I make those sawtooth lines that are used to mark subduction zones/boundaries?

https://preview.redd.it/uvj8dfn9eok81.png?width=2000&format=png&auto=webp&s=a152a7881324216c748dcd8a27572f532b2f505d

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👤︎ u/Stephlau94
📅︎ Mar 01
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A reconstruction of the Earth’s surface from 200 Million years ago to present day in jumps of 10 Million years. Red lines show the location of subduction zones, other plate boundaries in black, plate velocities are also shown
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📅︎ Mar 15 2019
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Rock 3. A free generator for believable and interesting worlds

World generator Rock 3 available now, free!

I've just released my free world-generator: Rock 3. By modelling geological and climate processes on the GPU, Rock 3 creates infinite believable and interesting earth-like planets in real-time. When you're happy with your world, save the elevation, heat, water, landmass, and biome maps in 2048x1024 resolution.

Download link: Rock 3 free on Steam

Context

I'm planning on making a roguelike, where 1000yrs ago, flora became a sentient hivemind, and turned on humanity. The few remaining humans live in small tribes on the edges of vast, dense, and horrifically lethal forests, reduced to scavenging to survive. Since the environment itself is the enemy, I needed a way to generate very interesting and believable random worlds. I've also been strongly considering having dimension-hopping being a core part of the gameplay, so I wanted world generation to be really fast, real-time even (but even without that mechanic, nobody wants to wait around all day for a new world to load every time they die). All that led me to building this tool, which I'm releasing because I've beed told it would be of value to others beyond the use I have in mind for myself.

Geological modelling features:

  • Variable density plates for plateaus
  • Subduction uplift for long mountain ranges along shorelines
  • Continental convergence for creased and wide mountain ranges
  • Transform boundaries for perpendicular rippling ridges
  • All other possible continental/oceanic boundary interactions (convergence, divergence, transform) each create unique features
  • Hot spots for island chains
  • You can also add meteor impact craters

Climate modelling features:

  • Sunlight energy absorption in ocean vs land albedo
  • Coastlines moderated and cooled by oceans
  • Altitude and air density modulates heat capacity
  • Hadley, Ferrel, and Polar wind cells creating low and high pressure tropics, modulating rainfall
  • Trade winds, westerlies, and polar easterlies carrying rain and cool/warm ocean air onto land
  • Windward sides of mountain ranges force rain out of the air, while leeward sides left with dry wind create rain shadows
  • Wind direction and strength controlled by planet spin direction and rotation speed

Planet/other features:

  • Generate planets built from up
... keep reading on reddit ➡

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👤︎ u/dawneater
📅︎ Nov 14
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Diamonds’ redox reaction origins revealed: Subduction zones – boundaries between tectonic plates where the Earth's crust sinks into the hot mantle – could be breeding grounds for diamond formation, according to Russian researchers. rsc.org/chemistryworld/20…
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📰︎ r/science
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👤︎ u/Libertatea
📅︎ Dec 04 2013
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Procedural world generator: Rock 3 now available!

Rock 3 available now free on Steam

I've just released my free world-generator: Rock 3. By modelling geological and climate processes on the GPU, Rock 3 creates infinite believable and interesting earth-like planets in real-time. When you're happy with your world, save the elevation, heat, water, landmass, and biome maps in 2048x1024 resolution.

Download link: Rock 3 on Steam

Geological modelling features:

  • Variable density plates for plateaus
  • Subduction uplift for long mountain ranges along shorelines
  • Continental convergence for creased and wide mountain ranges
  • Transform boundaries for perpendicular rippling ridges
  • All other possible continental/oceanic boundary interactions (convergence, divergence, transform) each create unique features
  • Hot spots for island chains
  • You can also add meteor impact craters

Climate modelling features:

  • Sunlight energy absorption in ocean vs land albedo
  • Coastlines moderated and cooled by oceans
  • Altitude and air density modulates heat capacity
  • Hadley, Ferrel, and Polar wind cells creating low and high pressure tropics, modulating rainfall
  • Trade winds, westerlies, and polar easterlies carrying rain and cool/warm ocean air onto land
  • Windward sides of mountain ranges force rain out of the air, while leeward sides left with dry wind create rain shadows
  • Wind direction and strength controlled by planet spin direction and rotation speed

Planet/other features:

  • Generate planets built from up to 92160 hexagonal cells
  • Alter the axial tilt, spin direction and velocity
  • Toggle atmosphere and ocean rendering
  • Toggle spherical vs flat projection
  • Choose where the "center" of your map is for the purposes of cartographical aesthetics

Technical details for those who are interested

As I need results in real-time, this rules out most/all "simulation" approaches. Simulations nearly always take a long time to converge on a solution, whilst being highly sensitive to initial conditions and arbitrary hand-tuned parameters, leaving very little room for experimentation or artistic modification. Furthermore, to get truly convincing results from simulations you need to simulate a *lot* of complexity, else you resort to just faking it, at which point why bother with a simulation?

Instead, I modelled

... keep reading on reddit ➡

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👤︎ u/dawneater
📅︎ Nov 14
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Future of the Walker Lane, Blanco Fracture Zone, and Gorda Ridge

I've taken and interest in geology in the last couple years, and have learned enough that you don't quite have to explain this to me like I'm a 5-year old. :-)

I've been recently reading a little about the Walker Lane. As I understand it, many geologists think that relative motion between the Pacific and N. American plates will over time transition from the San Andreas transform fault to the WL, with the WL becoming a sort of more tidy transform boundary.

So what will happen on the northern end of the WL? Will it propagate to the NW to connect with, what, the Blanco Fracture Zone? If so, does that process require the complete subduction of the Gorda Plate and Gorda Ridge before it occurs? Is the Pacific Plate going to steal part of SW Oregon as well?

I'm trying to picture where the future transform fault goes. Do we end up with the remnants of Shasta and Lassen on a big island off the Oregon Coast after the Juan de Fuca plate is gone and the JdF Ridge is subducted?

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📰︎ r/askgeology
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📅︎ Nov 21
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What does my handwriting say about me? :) reddit.com/gallery/zg53vn
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📰︎ r/graphology
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👤︎ u/ducanna12
📅︎ Dec 08
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a question I had as kid that was never answered.

hey folks,

when I was a kid I had a geography class where we talked about tectonic plates (if I recall correctly) and how they move and overlap each other... my question to the teacher at the time was something along the lines of "well what happens to ship wrecks when the plates overlap"

I recall she had this confused look on her face and basically ignored my question.... so yeah....here I am asking the same question 20 years later to reddit...

specifically, and forgive me if my terminology is all over the place, what would happen to ship wrecks present on the "trench at convergent boundary", would they be swallowed down the "subduction zone" ultimately turning into magma?...and if so does that mean we may have lost countless archeological artifacts to this process?

source of terms used here

https://cdn.britannica.com/34/3534-050-E46D8524/crust-Oceanic-destruction-theory-Production-Earth-plate.jpg

thank you in advance

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📰︎ r/askgeology
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👤︎ u/Asio0tus
📅︎ Jun 12
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Hear me out on this…

[Before you read this, please keep an open mind.]

[I will be referring to Hawaii as its correct name, Hawai’i, or Kingdom of Hawai’i, or Kingdom of Hawaii. They all mean the same in this report.]

What if ancient Hawaiians/Polynesians were the last remaining people of the Tartarian Empire or were their refuge?

Would they have been working with the native people, working hand in hand? Would they have created families with the natives and utilized their higher knowledge and resources for progression?

Would they have just been the original Polynesians?

Hear me out -

I am speaking more on behalf of Hawaii, rather than Polynesia as an entirety. As a proud Native Hawaiian, I feel more comfortable speaking about my own culture and home. I would like this to encompass all of Polynesia, but as far as history goes and providing facts, I am most knowledgeable of my Hawaiian History.

Hawaiians are the native people of Hawai’i. However, origins of the Hawaiian people are still unknown. In an article, “Hawai‘i became one of the last two major land areas on the planet to be settled when Polynesians from Tahiti and the Marquesas Islands navigated voyaging canoes to Hawai‘i in the 11th or 12th century. Settlers brought plants and animals needed to start taro farms modeled on those in their homelands and established chiefdoms using traditional norms of behavior and governance institutions from their home societies. Sometime round 1400, Hawaiians lost contact with the outside world and remained isolated for the next 350–400 years.”

Even with this information, this still poses the question of the origins of Polynesians.

Hawaiian chiefs were reported to be over 6 feet tall. These reports have been documented based on written documentation from foreign explorers. Way before written documentation, there’s a possibility that the average height for Hawaiians were much taller.

According to the Tartarian theory, the inhabitants of this empire were giants of an advanced civilization.

After arriving, the people of Hawai’i developed a subsistence economy. Land was divided in “ahupua’a” (ah-who-poo-ah-ah) - slices of land that extended from the mountains to the seas. With these ahupua’a, each one would be self sufficient. Each community in their ahupua’a would have all the resources that the other ahupua’a have. Hawaiians had their own education system. Hawaiians had their own economy. Hawaiians had high population growth rates.
Hawaiians established their own

... keep reading on reddit ➡

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📰︎ r/Tartaria
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👤︎ u/txexa
📅︎ Aug 09
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why did the first cratons form and why do continental plates exist?

When magma oozes up from the mantle at divergent plate boundaries or from hot spots like Hawaii, they form "oceanic plate material" that's low in silicates.

Then that stuff gets subducted under continental plates where it melts and bubbles back up but now when that lava comes out it forms high silicate "continental plate material".

But why? Where did the first cratons come from and why does continental plate material ever form? Why isn't it all oceanic plate material?

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📰︎ r/askscience
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📅︎ Jul 09
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Latest research articles published online [2022.07.05]

Physics

Astronomy & Astrophysics

Title: ALMA-IMF-II. Investigating the origin of stellar masses: Continuum images and data processing
Author: The ALMA-IMF Consortium, The ALMA-IMF Consortium, M. Armante, C. Battersby, L. Bronfman, J. Braine, N. Brouillet, E. Chapillon, J. Di Francesco, A. Gusdorf, N. Izumi, I. Joncour, X. Walker Lu, Men'shchikovA., K. M. Menten, E. Moraux, J. Molet, L. Mundy, Q. Nguyen Luong, S. D. Reyes-Reyes, J. Robitaille, E. Rosolowsky, N. A. Sandoval-Garrido, B. Svoboda, K. Tatematsu, D. L. Walker, A. Whitworth, B. Wu, F. Wyrowski
Volume: Astronomy & Astrophysics 662(0), A9 (2022)
URL: https://www.sciengine.com/doi/10.1051/0004-6361/202141681
DOI: 10.1051/0004-6361/202141681

Frontiers of Physics

Title: Asymmetric nonlinear-mode-conversion in an optical waveguide withPT symmetry
Author: Changdong Chen, Youwen Liu, Lina Zhao, Xiaopeng Hu, Yangyang Fu
Volume: Frontiers of Physics , 2022, 17(5): 52504.
URL: https://journal.hep.com.cn/fop/EN/10.1007/s11467-022-1177-y
DOI: https://doi.org/10.1007/s11467-022-1177-y

Title: Error-detected three-photon hyperparallel Toffoli gate with state-selective reflection
Author: Yi-Ming Wu, Gang Fan, Fang-Fang Du
Volume: Frontiers of Physics , 2022, 17(5): 51502.
URL: https://journal.hep.com.cn/fop/EN/10.1007/s11467-022-1172-3
DOI: https://doi.org/10.1007/s11467-022-1172-3

SCIENCE CHINA Physics, Mechanics & Astronomy

Title: New self-consistent effective one-body theory for spinless binaries based on the post-Minkowskian approximation
Author: JING Jiliang, Long Sheng, Deng Weike, Wang Mengjie, Wang Jieci
Volume: SCIENCE CHINA Physics, Mechanics & Astronomy (2022)
URL: https://www.sciengine.com/doi/10.1007/s11433-022-1951-1
DOI: 10.1007/s11433-022-1951-1

SCIENTIA SINICA Physica, Mechanica & Astronomica

Title: 一种确定纳米压入接触面积的简便方法
Author: gong jianghong, liu ming
Volume: SCIENTIA SINICA Physica, Mechanica & Astronomica (2022)
URL: [https://www.sciengine.com/doi/10.1360/SSPMA-2022-0208](h

... keep reading on reddit ➡

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👤︎ u/Badatu
📅︎ Jul 06
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The geography of Ouven and Glacus.

Ouven is a continent in my as of yet unnamed fantasy world, and the Kerrich Empire's biggest rival. It is near the north pole and close to the northern ice sheet. It is situated on the continent of Glacus and seperated from Kerrich only by a geographic feature known as Sundathe which is an isthmus at low tide and a channel at high tide. To explain Ouven, however, we need to talk about what is to the north.

The north pole of this unnamed world is situated on a mountainous region of Glacus that recently collided with the rest of the continent. Northern Glacus is surrounded by subduction zones on the coast and is at a convergent boundary with the rest of the continent. Before the last ice age there were highlands in the center but those have since been covered with ice. The mountains that connect the north to the rest of Glacus, the Fossif mountains, are home to many outflow glaciers. As these glaciers flow, it eventually gets too hot and they melt.

It is this glacial meltwater that is the lifeblood of Ouven. Because Ouven lies in the rain shadows of many mountains, it should by all rights be a desert, but because of the draining of the ice cap, it has mighty rivers, many of which unite to form the Sermeqogene River. These rivers begin in the mountains, and pick up a lot of sediment of such a type that Ouven's soil is quite fertile thanks to the rich phosphates of the Fossif mountains, and the seasonal flooding caused by faster glacial melting in the summer. However, the river does not deliver much nitrogen although this is not a problem for nitrogen fixing plants, so accordingly, the main staple crop of Ouven is a type of bean.

Apart from the lack of nitrogen, Ouven's agriculture is very productive, producing large amounts of nitrogen fixing crops yielding enough of a food surplus to feed many large cities, and still have more than enough to export across the world. This has made Ouven the beanbasket of the world.

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📅︎ Jul 07
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City Council Meeting Notes 11/3/21

Link to Previous Post

Meeting Agenda

Notable Items on the Agenda:

  • Updates and progress on the City's various efforts to address our Homelessness and housing affordability crisis, including the council issuing a Request for Proposal (RFP) for outdoor shelters
  • Establishment of the American Rescue Plan Act (ARPA) Community Assistance Grant Program

Work Session

It's Wednesday my dudes! You know what that means. Time for internet denizens still living in 2018 to post pictures of frogs, and time for me to sit on my couch and wait for the council meeting to start. Which it has! Hello everyone. All of council looks spiffy today.

Direction on Restricted Tourism Reserve Account

City Attorney Ian is here to give us a drama recap. When someone stays at a hotel in Bend, the City levies a small tax. According to State law, 35.4% of that money needs to be used for tourism. The City Council tried to reduce the amount of money earmarked for tourism a few years ago to spend it on useful things like roads, but our local hotels sued the council to prevent the reduction. The City lost the lawsuit, and then appealed. and then lost the appeal. This whole time, the City Council has been saving that money, and now we have just under 2 million dollary-doos to spend on tourism promotion and "tourism-related facilities". The question now is what to spend it on. I keep saying we should use this rare opportunity to build a zipline over Drake Park, but nobody listens to me.

The City has 2 broad options:

  1. Defer to upcoming contract cycle (give it to Visit Bend)
  2. Develop a separate process / RFP and decide what to do with it ourselves, while keeping the Tourism industry involved so they don't sue us again.

Councilor Goodman likes option 2. She wants to know if they could allocate the money to a specific RFP / Project. Answer: Yes.

City Manager and the Attorney emphasized that if we don't give it to Visit Bend, we really need to make sure it's solidly in the "tourism related" category to avoid additional litigation.

Councilor Goodman wants to use the money for public restrooms downtown.

Councilor Kebler also wants option 2, is specifically interested in using it Downtown.

Councilor Campbell wants to know how the Visitor Center downtown is funded. It is not funded by the General Fund. She wants to

... keep reading on reddit ➡

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📰︎ r/Bend
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📅︎ Nov 04 2021
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23/06/22 - Plate Tectonics 2

Another swing at creating a platform form which to create the landmasses has been created. With the second attempt I tried to simplify the plates. It's a guideline, it's not a geological accurate representation, as I am not sure if that would add anything extra to the end goal.

There is going to be a lot of trial and error when it comes to landmapping. I want to set a nice foundation that can show the terrain and climate at a level of detail that will help myself and others later on down the line.

I'm still in the brainstorming phase of this. I think the best way to go about it is a little bit of experimentation to find the right scale at which we can gather information about a certain region without doing too much 'book-keeping'. However, I want to avoid the map becoming a mess of colors, and factoring in a height map is also going to be something to consider visually.


Here is the current layout for the Plate Tectonics It's a bit simpler than before. It has two large seperation zones, simplistic plate motion to indicate continental drift, hotspots, convergence lines, subduction lines, and areas of orogeny. Boundaries do not indicate landmasses directly, nor are mountains and volcanoes exclusive to hotspots and orogenic areas, they are simplistic to allow a wider birth of freedom when creating the map, and yet provide me with some sort of stick to wade through the mud with.

The next stage will be to experiment with a small landmass, and see if I can create something at the level of detail I want, balanced against time-spent, as well as assessing how the plate-guidelines effect it's creation.

Regardless, I've had a lot of fun so far and I am excited about the next stage.

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📅︎ Jun 23
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Tectonic plates terminology

I have a very basic doubt regarding what the tectonic plates mean. In Wiki article Subduction is defined as:

>Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries.

and when I follow the link to convergent boundary it is defined as:

>A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide.

Now from what I know is that the tectonic plates comprise of oceanic and continental crust and convergent and divergent boundaries exist where two tectonic plates meet. So this subduction should only happen where two or more major or minor plates meet and not between continental crust and oceanic crust. So do plates sometime refer to crust as well and there are more minor and major plates which are still not defined.

Edit(to clear things up) : Is there a possibility of subduction of oceanic crust and continental crust of the same plate?(If answer is yes then these crusts can also be called plates)

And Thanks for your responses!

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📅︎ Oct 06 2021
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The Geology of The Eternals

A few disclaimers before I dive in: I am a geologist, but my main specialties are mapping, engineering geology and petrology, so feel free to contradict or question my speculation. I know Kyle Hill could do it better, but I am who I am. Also, I loved the movie, so this is written as a sort of fun discussion of the real-life implications of some of the events, not in an attempt to excoriate the movie.

The Eternals, specifically the idea of a Celestial being seeded and then beginning to arise from the earth, gave me a lot to think about geologically.

First, the seed: The Celestial seed being implanted in the earth was shown as sort of a minor crater hitting the earth, but I can't see a way of anything with mass making it all the way to the core. Even a very heavy metal would likely melt and become incorporated and mixed with all the other heavy elements towards the center of the earth, losing its integrity. Now, if the seed were essentially without mass, like a photon or some type of radiation, that could possibly work.

Second, the "global earthquakes." In normal cases, a global earthquake is impossible, because earthquakes originate from one place - the hypocenter - and no amount of energy could cause the strain of an earthquake to transfer from the adjoining plates to other plates. Even a tremendous amount of movement along the Alaskan subduction zone, for example, could not transfer its strain to the mid-Atlantic ridge because they occur on their own discrete plates.

So at first I dismissed the idea of a global earthquake outright - until I realized that this earthquake presumably would be caused by Tiamut beginning to stir and grow, and so there would be multiple hypocenters - multiple plates shifting at the same time. Thus, a global earthquake with one hypocenter - not possible, but global earthquakes with multiple hypocenters occurring at the same time - sure, why not?

Now, to the big one: Tiamut's emergence. Like some others, I thought that Sersi was freezing the surface of Tiamut until the news report mentioned he was marble. This is because native ("in the wild") marble usually does not have the beautiful, perfect appearance of carved marble as seen in the movie. But Sersi can create whatever type of marble she wants, and I want nothing more than to climb Tiamut's head and hands.

I appreciate the movie showing a good sense of scale with Tiamut with the little islands being completely swallowed up - however, as others have mentioned, with an ev

... keep reading on reddit ➡

👍︎ 105
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👤︎ u/Silestra
📅︎ Nov 19 2021
🚨︎ report
I'm looking to understand this evidence for the CPT model better.

I'm studying the Catastrophic Plate Tectonics(CPT) model of the Flood and I've come across a slightly more technical but riveting argument in its favor.

The theory of plate tectonics proposes that continents have been moving for billions of years. At a convergent plate boundary one plate will subduct under another plate. The oceanic crust from the subducting plate pushes into the mantle. Subduction happens at a rate of 2-8 centimeters or 1-3 inches a year.

Depiction of a subducting plate

The CPT model agrees on many concepts with PT but disputes the history of it. While we observe subduction today at a diminutive rate, CPT is based on evidence that subduction happened rapidly in the past, specifically during the year of the flood.

In the 1980's, John Baumgardner, who holds a Ph.D in geophysics and space physics, predicted that the oceanic crust from a subducting plate would still be colder than the surrounding mantle if it rapidly subducted only a couple thousand years ago. A decade later, the technology was developed to prove his hypothesis.

Cold oceanic crust surrounded by the mantle

Plainly put, if the crust subducted into the mantle tens of millions of years ago, at rates of inches per year, the crust should be uniform temperature with the surrounding mantle.

https://www.icr.org/article/cold-slabs-indicate-recent-creation

Taken from article above (wrote by Ph.D geologist Timothy Clarey):

> All of the images of the subducted slabs show consistently cooler rock surrounded by extremely hot mantle, even after traveling more than 1500 km (930 mi) right through the mantle itself.3 These rock slabs appear to be at least a thousand degrees Celsius cooler than the surrounding mantle material at these depths, based on their density.4

>And a bigger problem was never addressed in this paper. How do the cold slabs that extend down to the base of the mantle (at the core boundary) remain cold after 30-50 million years or more, at the sluggish subduction rates secular scientists envision? These lithosphere slabs had to travel 2,900 km (1,800 mi) to reach the base of the mantle where the temperature is even hotter, about

... keep reading on reddit ➡

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📰︎ r/Creation
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📅︎ Oct 21 2021
🚨︎ report
Ratio

Core+Planet+Brittle Crust+Mantle+Radius+Uniform+Radioactive Decay+Compression+Collision+Accretion+Temperature+Melting Point+Pivotal+Iron Catastrophe+Rapid+Molten+Buoyant+Silicates+Exterior+Heavy Metals+Gravitated+Planetary Differentiation+Furnace+Geothermal Gradient+Boundary+Mineral+Alloys+NiFe+Dissolve+Siderophiles+Precious Metals+Vast+Geologic+Speculated+Abundance+Conundrum+Precise+Rotation+Composition+Bullen Discontinuity+Outer Core+Viscosity+Deformed+Malleable+Convection+Churning+Magnetic Field+Dense+Atmosphere(ATM)+Interpret+Plasma+Crystals+Axis Of Rotation+Orientation+Seismic+Waves+(Hexagonal Close-Packed aka HCP)+Solidify+Freezing Point+Subduction Zones+Tectonic Plates+Lithosphere+Superplumes(LLSVPs)+Hot Spots+Volcanism+Hemispheres+Distinct+Inner Inner Core+Radical+Curie Point+Atoms+Geo-dynamo+Fluid+Conduct Electricity+Equator+Coriolis Forces+Currents+Artifact+Crucial+Solar Wind+Ozone Layer+Ultraviolet Radiation+Fluctuates+Magnetic North+Geomagnetic Pole Reversals+Catastrophic+Glacial Activity+Volcanic Eruptions+Sophisticated+Shock Waves+Earthquakes+Velocity+Frequency+Body Wave+S-Wave+Altered+Transmit+P-Waves+Meteorites+Asteroids+Chondrite+Peek+Solar System+Diamond Anvil Cell+Simulate+X-ray+Laser+Complex+Modeling+Ratio

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📰︎ r/copypasta
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📅︎ Jan 06
🚨︎ report
Formation of new volcanoes in the Cascades?

After reading about how the cinder cone Paricutin rose out of a farmer's field in Mexico in 1943, this has got me thinking about a few questions:

  1. Is it possible for this kind of event occur in the Cascades?
  2. Is it possible for a new stratovolcano edifice to form somewhere along the Cascade range?
  3. Approximately how long after subduction at a plate boundary begins would volcanoes form? for example, let's say that the Atlantic ocean were to suddenly start subducting under North America, approximately how many millions of years would it take before there are volcanoes on the east coast?

I have done some searching into these questions, but I have found it difficult to find any answers

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👤︎ u/Skiracer6
📅︎ Apr 23 2021
🚨︎ report
OBLIGATORY FILLER MATERIAL – Just take a hard left at Daeseong-dong…6

Continuing.

After the third pony keg of beer was delivered, it was decided that the next few days would be spent in the conference room discussing what we thought was the best way forward.

We wanted dry-erase boards so we could start taking detailed notes, even though I was well ahead of the curve in that regard. We instead ended up with some mobile elementary-school blackboards and a pile of grainy, sooty chalk.

Leave it to Dr. Cliff to go into a discourse on the genesis of chalk and its economic importance.

Bloody carbonate geologists.

Bloody White Cliffs.

We geologists need to punctuate their conversations with pictures, so these would suffice quite well.

At 1700 hours, the official end to the workday was called; we’d meet here again tomorrow. I’m not certain by whom, but it was readily agreed upon. We were more or less on our own until 1000 the next day. I needed to spend some time in my room with my notes and update a number of dossiers, field notebooks, and other items I was using as a running chronicle.

Several folks decided to invade one of the hotel’s restaurants for dinner. Some wanted to head to the casino, a couple wanted to get a massage, and others wanted to do what tourists are normally wont to do on the second day of being a foreigner in a foreign land.

I declined invitations to dinner and other activities, as I had a long writing session in front of me. I wanted to get this all in its proper place while the memories and notes were still fresh.

30 minutes later, in my room after a 25-minute wait for the elevator; I’m updating dossiers, creating several new ones, and updating my field notebooks. Suddenly, after an hour’s work, I notice something is amiss.

“I don’t have a drink or a cigar,” I said to the four walls. “This. Will. Not. Do.”

I was used to Happy Hour in Russia. Happy hour is slightly different; there are no ice cubes or orange-peel twists in the vodka. Also, it lasts all day.

I remedy that situation by finding and clipping a nice, oily oscuro cigar and digging the bourbon out from under my boxer-briefs in my dresser drawer. I heft the bottle and feel that it’s significantly lighter than when I left it last night. I happen to look in the trash can and spy the wrapper for a box of my festively colored Sobranie cigarettes I obtained back in Dubai.

“Hmmm”, I think, “It would appear that we have some light-fingered Cho Louies or No Louises around here. I’d best guard my supplies a little more securely.”

I mo

... keep reading on reddit ➡

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📰︎ r/Rocknocker
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👤︎ u/Rocknocker
📅︎ Apr 13 2020
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DEMOLITION DAYS, PART 69

Continuing

“Yes, sir!”, and he’s gone, off down the hall, and out of sight.

I set up my portable office, kick off my boots and back brace, and realize that I’m tired.

I also need to make a few calls. Esme first.

“OK, let’s see. I’m 14 hours ahead.” I ponder, “Guess I’ll just send off some Emails, and let the calls go until I get to Taiwan.”

Right after doing so, there’s a knock at the door. It’s my redcap friends with a serving cart.

“Right over here, thanks”, I tell him as he unloads everything onto the bar.

I inspect what he’s found for me.

Żubrówka Bison Grass Vodka”, I say, “Very nice. Bitter lemon, limes, ice…couldn’t be better.”

Then he tells me that there’s little change from the funds I had supplied him earlier.

“Prices expensive here. Even more so at the airport.” He explains.

“I can understand that”, I say, “Can I see a receipt? Not that I don’t trust you, I need to figure out a tip.”

He was right, it was damned expensive. Glad I’m not paying for it.

I fish around in my wallet and find another double sawbuck to hand over.

He thanks me and tells me that if I need anything else, just call.

“I’m good. Thanks.” I reply and shut and lock the door.

Realizing that I’m rather hungry, I order up a load of Dim Sum and “Crab Indulgence” from room service. The food, though pricey, was worth every shekel.

I leave a wakeup call with the front desk for 8 hours hence.

I spend time going over our itinerary and my field notebooks. Convinced they’re as far as I can take them at this point in our journey, I retire to the Jacuzzi with a couple of stiff drinks, cigars, and the latest copy of Science magazine.

I’m such an unrepentant hedonist.

I decide to leave Mr. Sin to his own devices. I need a bit of recuperation time, these 16-hour flights can really wear one down.

The phone rings what seems like 10 minutes later. Checking my Omega, I groggily realize it’s my wake up call. Time to fly again.

I quickly shower, dress, and head down to the front lobby. I settle up my bill and look around for Mr. Sin.

He’s nowhere to be found, and I don’t have any way to contact him…unless he’s still in his room.

I go to the front desk and ask them to ring his room.

After 20 or so rings, he groggily answers the phone. Luckily, the hotel staff relays my message that he needs to get his skinny ass down here as our flight is going to be leaving soon and we, oddly enough, need to be on it.

He replies in the affirmative. I tell him to mee

... keep reading on reddit ➡

👍︎ 117
📰︎ r/Rocknocker
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👤︎ u/Rocknocker
📅︎ Jan 17 2020
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Antipodal Impact Volcanism Hypothesis Redux

backpages

original Impact Events and the End Permian Mass Extinction to r/geology

1st redux Impact Events and the End Permian Mass Extinction, or the antipodal cause of trap volcanism hypothesis (rejected in r/geology) • r/FringeTheory, being a copy of previous, in less hostile audience...

2nd redux More math on relationship of meteors and their craters, plus a list of articles about my thesis on meteor impacts and extinction events

look to stars, map

refs on south sandwich tectonic plate

this post is 3rd redux

update regards antipode features Atlas Pro looks at Mars topography, which illustrates antipodal hypothesis.

Thinking about an article on Hawaiian geology, containing a time-line of extinction events shown as a bar graph, I noticed how similar is Hawaii to Reunion Is. Next, what extinction event might be associated to hypothetical impact crater and resulting mid-pacific-ocean hot spot?

First I did the math again (and again, had trouble imagining this right).

Hawaii
Latitude 18° 55′ N ... 19°S
Longitude 154° 48′ W ... (155-35)W-180 = (60E)
antipode lat 19°S 60°E (east of Africa off coast of Madagascar) see map nothing there

This point is coincidentally near a volcanic ridge spread across seafloor because Reunion Isl. is a hotspot created by the Chicxulub meteor. This tells us nothing about the Hawaii hot spot due to plate drift over 146My.

Hawaiian chain is supposed to be 80Mya, is there sign of extinction around that time? Just a small bump see bar graph We see

... keep reading on reddit ➡

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👤︎ u/acloudrift
📅︎ Jul 26 2021
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Realistic World Building Animations

I came across some animations by Chris Scotese which gave me quite some insight into plate tectonics and climate. Most of the animations are backed up by academic papers and use publically available data and tools like Gplates.

  • 1.5b years of plate tectonics. Notice how plate boundaries are not static. I think the blue arrowed lines are subduction and red lines rifts (spreading plates). Another animation by a different researcher and a 3d vid.
  • In this vid, notice how the climate bands change with landmass. (-540m to modern)
  • Australian indigenous culture (20-60k years old) predates the last Ice Age! Many of the seeds of modern society were starting to form just 20k years ago at the end of the last Ice Age.
  • As an aside, this vid on the history of Europe popped up. (just 2.4k years) and a history of urbanisation (vid and paper)

What I really got from this is that you can apply a time and location to most things. If you don't like how it looks in the present, look into the past or project into the future cos everything is always changing. This has really got me thinking about timelines and more dynamic worlds.

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📅︎ Feb 05 2021
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(Spoilers Extended) Possible mineralogy of the oily black stones

I'll preface this by saying that I only want to point out something in from our real world that reminds me so much of Planetos' oily black stones: chromite and ophiolite deposits.

Chromite (wikipedia) — (Fe, Mg)Cr2O4 — is a chromium resource. Chromium is a critical compotent of modern steel (~13% Cr makes steel stainless. And harder as we found out in the 1800s). As to whether ASOIAF's steel contains it, therefore establishing knowledge and demand of it, I wouldn't know. (The maester links have steel and valyrian steel, but no mention of chromium. In which case, any chromite deposit would not be purposely mined out, leaving it where it sits).

So anyway, why I always think of chromite everytime I hear "oily black stone" is because of the mineral's diagnostic property of luster. That and its color and where it is usually found.

In my time at uni, we identified the mineral chromite by its iron-black or "pitch black" color, a metallic or "greasy" luster, and a brown streak (streak is a mineral's color in powdered form but won't be discussed in this post due to lack of info).

Looking at it now, mineralogy websites don't mention the "pitch black" color (only "black") but mindat.org includes "greasy" for chromite's luster. Moving on.

>The throne of the Greyjoys, carved into the shape of a kraken from an oily black stone.. (WOIAF)

>Born a bastard on the Iron Islands, [Maester] Theron noted a certain likeness between the black stone of the ancient fortress [of Oldtown] and that of the Seastone Chair.. (WOIAF)

Oily is just another word for greasy. That is even how the stones of Asshai are described in WOAIF:

>Some say as well that the stone of Asshai has a greasy, unpleasant feel to it, that it seems to drink the light, dimming tapers and torches and hearth fires alike. The nights are very black in Asshai, all agree, and even the brightest days of summer are somehow grey and gloomy. -Asshai-by-the-Shadow

Remembering chromite with pitch black color, and the notion of black stone that "seems to drink the light" (like the image of pitch as in viscous tar) is just so amusing to me everytime I read the line.

Chromite (SG= 4.5 to 5.1) is half as dense as silver or twice denser than Earth's average crustal density (2 to 2.6) but whether it's as dense as the oily stone blocks, it's hard to make sure:

>Maesters and other scholars alike

... keep reading on reddit ➡

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📰︎ r/asoiaf
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👤︎ u/yatoen
📅︎ Jul 01 2020
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Ha'amonga 'a Maui, a lonely trilithon

https://preview.redd.it/tb104fwqe3g41.jpg?width=2000&format=pjpg&auto=webp&s=d2017a15270c173bf678e2893ed10ffdf22b561a

This is the Trilithon of Ha'amonga 'a Maui. It is located in Tonga, it is the only trilithon in the entire region, and the visible part of each upright stone is estimated to weigh 30-40 tons.

It is believed to have been built in the 13th century as an entryway to the reigning monarchs royal compound. Oh, wait, no it isn't.

According to wikipedia, it could have been built at that time, or it could have been built in the 6th century as 'an astronomical observatory.' These two accounts conflict wildly, differ by seven hundred years and distinctly show that we have no real idea where the trilithon came from at all.
This means that there is absolutely no set date for its construction, and I see no reason why the structure couldn't have been appropriated as both an astronomical observatory in the 6th century, then later as a gateway in the 13th. What we might be seeing is two uses of an already existing structure. No reason to believe either of these dates are when it was actually built.

Human for scale

Local legend says it was created by the god Maui, which ties into the supposed origins of a lot of different megaliths - that they were either created by or for various gods. Believers in ancient aliens and the like would probably say these tales are a primitive recollection of alien visitation, but I see no reason to come to this conclusion. Humans absolutely can and have lifted and cut stones of this size, its just a question of when and by whom.

The two standing stones in this trilithon are absolutely huge, and we have no idea how far they have sunk into the ground over the past (bare minimum) 700 years. For all we know they could be significantly bigger than people think - just like how the easter island 'heads' have bodies underground and so on.

There is a hell of a lot of speculation on websites like ancient origins and the like that claims all sorts of things about the astronomical uses of such a megalith, the purpose of the structure, and so on, but obviously there is no real way to know for sure what its purpose was. But I am not here to talk about its purpose.

What I believe to be the most significant aspect of this megalith is its uniqueness to the region.

... keep reading on reddit ➡

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👤︎ u/marscr100
📅︎ Feb 10 2020
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Grow your rock collection! Summer Rock Hunting Guide!

Rocks? What can be cool about rocks? Well, ol' planet earth is pretty cool and can create some pretty sick rocks. Heres the officially unofficial rock collecting guide for summer 17' by me, u/Pebblezcrwd

NOTE I do not recommend going ham on some pretty rock outcrops, as geovandalism is a thing and it pisses off a lot of geologists and ruins certain areas. If it is not loose or on the ground don't smash it out of the cliff. Professors and post grad students have trouble teaching and learning when theres no outcrop left.

Northland

If you're heading up here, mate you're in for a good time! Northlands geology is fantastic! A while ago, the Northland became the plate boundary. Rather then being conventional, Northland decided not too and the pacific place obducted (Went into and over the continental crust) and spliced throughout the Northland region. This lead to some pretty cool rocks. My personal favourites are Plutonic rocks, which are your Granites, Diorites, Gabbros etc. They tend to have massive crystals. Anywho, In Northland you can pick up some pretty rare rocks due to the history. I'll only list the rocks I think are pretty cool, however Northland mainly consists of older volcanics, allochthonous plate material and new Zealands national rock, Greywacke!

-Serpentinite. This is kind of a piggyback on the Basalts in the area. Different to serpentine, as it is a boring black rock on the outside, however if you crack one open, its all shiny and green on the inside. Specific locations are numerous, but anywhere there is an aggregate quarry for Basalts, try whacking a few of those rocks, you'll get lucky for sure!

-Gabbro. North Cape, most eastern side of the Surville cliffs.

-Peridotite. This is a pretty one. On the northern side of North Cape, the cliffs consist of Peridotite. Might be a hassile to find non-serpentinised versions but its worth it!

-Granodiorite. This comes as intrusions within the Andesites of Whangarei's Bream head area. I like this rock alot.

Auckland

You guys sit on some pretty cool rocks, and around volcanoes. As an avid volcano lover, I am jealous. After driving around your city, I am not.

-Olivine. This is not a rock, but a mineral within Basalt. It's a green or a blue-green teal and is very pretty, 10/10 would collect it. You can find gem quality Olivine in the lava flows around lake Pupuke (The first volcano in the current Auckland field).

Auckland is basically all Basalt and mud, no

... keep reading on reddit ➡

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📰︎ r/newzealand
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📅︎ Dec 02 2017
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An idea for a prospecting competition

Stuck at home with a little too much time on my hands, so apologies in advance for attempting to entertain myself on the Reddit.

For some reason the idea of finding a little (but not totally insignificant) gold in areas that just aren't very geologically favorable, with very sparse mineralization, appeals to me -- a bit masochistic, I know. Seems to me that finding gold in such areas demonstrates pretty serious powers of research, good knowledge of geology, etc.

One sometimes wonders just how good some of those YouTuber prospectors are. So I was thinking a competition in a mineral-poor (but with some gold) geological area might be entertaining -- and I think I have just the area: the Oregon Coast Range (OCR).

The Siletzia terrane underlies and is exposed in places in the OCR. Siletzia was a huge pile of mostly basalt that accreted to the N. American continent 50-something million years ago (and in so doing, it actually jammed up the old subduction zone). We're talking submarine pillow basalt, sandstone and siltstone from a sedimentary basin, etc. The California Motherlode Country it ain't -- but, there was some magmatism and volcanism that occurred after the terrane accreted. There are fairly extensive nepheline syenite sills, camptonite dikes, and other interesting intrusive phenomena here and there, that might provide control for hydrothermal deposits. And one does find the occasional chunk of vuggy quartz-sulphide vein in its rivers.

Also, there were in fact a couple short-lived mining districts in the OCR -- but it's not clear to me if anyone actually found any gold at all, or if it was all just chalcopyrite-fueled momentary group hysteria. There certainly wasn't much -- a few reports from the late 19th century, discussing the region generally, make mention of there being a "little" color to be panned in this river or that in the OCR.

I do suppose there has been a very small amount of gold found -- from just extremely small, very localized occurrences, so that there was just a tiny bit of color in small portions of some of the streams. The goal would be to find these hyper-localized deposits.

So I would propose a competition. Garret (or some like company) could sponsor the event and bring in a handful of reasonably well-known YouTubers:

* They have have some defined time period to get gold out of the OCR.

* They may use pans, small in-stream sluices, and detectors.

* They may not go south of the Siletzia terrane -- NO Siskyous or Kl

... keep reading on reddit ➡

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👤︎ u/PDX_Web
📅︎ Apr 01 2020
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D20x5 Astounding Alternate Histories
D20 This alternate history diverges during
1 the Paleolithic (3,300,000-11,650 years ago).
2 the Neolithic (12,000-6,500 years ago).
3 the Bronze Age (5,300-3,200 years ago).
4 the Iron Age (3,200-1,500 years ago).
5 the Middle Ages (1,500-500 years ago).
6 the time of the Mongol Empire (1206-1380).
7 the Renaissance (15th-16th centuries).
8 the Mamluk dynasties (1250-1517).
9 the Victorian era (1815-1914).
10 the Romantic era (1770-1815).
11 Classical Antiquity (480 BC-476 AD).
12 the reign of Tokugawa Ieyasu (1603-1605).
13 the life of Jesus Christ (0-33 AD).
14 the campaigns of Alexander the Great (336-323 BC)
15 the Industrial Age (1760-1970).
16 the Machine Age (1880-1945).
17 the World Wars or their interwar period.
18 the Three Kingdoms period (220-265 AD).
19 the recent past (2000-present).
20 the Cold War (1947-1991).
D20 The cause of this alternate history's divergence was
1 a minor religion in our history becoming dominant over others.
2 a pandemic.
3 an anachronistic technological innovation.
4 a natural disaster.
5 the different outcome of a war.
6 an economic collapse.
7 a breakthrough in animal or plant domestication.
8 an alliance between two powers.
9 the discovery of a vital resource.
10 the untimely death of a vital historical figure - not necessarily a famous or even known one.
11 a ruler making a better decision than they did in our history.
12 the beginning of a golden age.
13 a shift in climate.
14 a political revolution.
15 a sudden evolutionary leap.
16 a cultural exchange.
17 a philosophical innovation.
18 unclear, the result of emergence from microscopic initial differences from our history.
19 the non-occurence of a catastrophe.
20 Alien Space Bats (i.e. some truly weird shit).
D20 The regional epicenter of this alternate history's divergence was
1 East Asia.
2 South Asia.
3 the Fertile Crescent.
4 North America.
5 North Africa.
6 Central America.
7 South America.
8 Northern Europe.
9 Southeast Asia.
10 Australia.
11 Central Asia.
12 the Middle East.
13 Central Africa.
14 Southern Europe.
15 Southern Africa.
16 Eastern Africa.
17 Western Africa.
18 Western Europe.
19 Eastern Europe.
20 the Arabian peninsula.
D20 The ultimate result of this alternate history's divergence
1 is a relative dystopia.
2 is a relative utopia.
3 is world domination by a tyrannical hegemon.
4 is human extinction.
5 is a state of international tension that makes the Cold War seem like a sunny summer day by comparison
... keep reading on reddit ➡

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📰︎ r/u_semiurge
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👤︎ u/semiurge
📅︎ Jul 01 2021
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OBLIGATORY FILLER MATERIAL – Just take a hard left at Daeseong-dong…11

Continuing…

That being handled, I leave a wakeup call for 0430 as I want a shower and a couple shower-sunrisers before we leave. It takes me about 10 minutes to pack. I call home to let Es know what’s going on. She’s not in, so I leave a message. Same for my friends Rack and Ruin of the Agency. They’re thrilled so far with my reports.

The security forces here are absolutely going to freak if they reverse-review my phone records once we leave.

Covert? Schmovert. I’m too old for playing such games.

The next morning, after a sudsy shower and a couple of vodka-infused shower-beers; I’m in the lobby with all my kit, checked-out, and waiting on the tour leader. My passport was stamp-stamp-stampity-stamped here at the hotel, which I thought was weird, but after spending time in this here country, not all that unusual.

At 0545 on the dime, the tour bus pulls into the lot. Without a word, bellhops grab near all my kit and escort it out to the waiting bus.

After tipping each extravagantly, I fire up a huge cigar, and wander around outside, loitering by the bus. I see members of my team at the front desk, checking out. Everything’s been paid for already, they just have to sign documents that they’re not secreting hotel towels or televisions or errant nationals in their luggage.

It’s a weird country.

I see them loading box breakfasts for us as well as box lunches on the bus.

Hell, they’re actually doing ‘field trip’ correctly.

If the bus us fueled up, we can go for days at this rate. There are several coolers bearing the hotel’s brand and I sidle over to see what they’re carrying.

Case after case of iced-down beer and a couple of cases of various high-octane potables; and over there? A couple of boxes of mixers…ah, soda…pop…carbonated citrusy goodness.

“OK”, I sigh, “All is as it should be. Now the field excursion may begin.”

My teammates filter outside as does their luggage. I suggest they get out and keep what is necessary for preliminary outcrop excursions; such as a backpack or knapsack, hammer, acid bottles, field notebooks, Brunton compass, lighters, cameras, personal tobacco products, and the like in the bus. That way, we don’t have to go tearing through all the luggage at every stop.

I pull out a bundle of 100 Hubco™ large geological dual-sample bags. That’s right: ‘dual’ sample…

I distribute these to everyone on the team

... keep reading on reddit ➡

👍︎ 112
📰︎ r/Rocknocker
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👤︎ u/Rocknocker
📅︎ Apr 26 2020
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The orogeny of northeastern Middle-Earth

Although plate tectonics didn't become mainstream science until after Lord of the Rings was published, a map of the Misty mountains eastward presents an interesting and geologically feasible history of that area of the continent, as well as an explanation of some of the layout of Moria.

The names of both mountain ranges provide a distinction between the two. The suffix "-aeglir" is a series of peaks, whereas the word "Ered" is a series of mostly separate mountains. These two different names point to a difference in structure, implying a difference in the processes that formed each.

The Ered Mithrin appear to decrease in size (judging from a map of middle-earth) as they approach the misty mountains, after which, they end and do not extend further westward. The Ered Mithrin end at the Misty mountains as the continental boundary destroys any geologic record by subduction. Even the name and appearance of the Ered Mithrin as a series of mountains indicate that they are a series of extinct hotspot volcanoes, similar in nature to the Hawaiian islands on Earth.

The misty mountains themselves, however, are described as not a chain of mountains (ERED Mithrin), but as a series of connected peaks (hithAEGLIR) with especially tall peaks interspersed throughout. This appears to be a typical continent-continent convergence zone, complete with crumple zones on either side of the mountains.

The presence of tunnels deep at the roots of the Misty mountains are further evidence of an active ancient subduction zone. As the Misty mountains were raised by Melkor, some crust would have been forced under other crust, generating convergent-boundary volcanism. As these volcanoes went extinct as the mountains finished forming, the magma chambers and tubes left behind would have drained. It's entirely feasible that somehow, a magma tube to the top of an extinct volcano could have been connected to a magma chamber at the base of the mountains, forming the basis for the stair from the "lowest dungeon to the highest peak".

Such are the ramblings of a bored geologist.

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👤︎ u/eren_kesef
📅︎ Oct 24 2016
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Nepal Earthquakes

Edit: There are some good questions in here related to building damage, culture, etc that I can't really answer, so I'm very much hoping that other experts will chime in.

This is a thread to discuss science related to the Nepal earthquakes. I will give a geophysical perspective, and it would be great if people from other fields, such as civil engineering or public health, could chime in with other info.

There have been dozens of earthquakes in Nepal in the past few weeks, the biggest being the magnitude 7.8 Gorkha earthquake and yesterday's magnitude 7.3 earthquake. Tectonically, this is a collision zone between the Indian subcontinent and Asia. This collision zone is unique, at least with our current configuration of tectonic plates, because the Indian plate is actually sliding under the Eurasian plate. When this happens at an ocean-land or ocean-ocean boundary it's called subduction. In a usual subduction zone, oceanic crust from one side of the collision sinks below crust on the other side, and goes deep into the mantle. However, in the India-Eurasia case, both sides are continental crust. Continental crust is less dense than oceanic crust and cannot sink. Therefore, the Indian plate diving underneath the Eurasian plate floats on top of the mantle, creating an area of double-thick crunched up crust, AKA the Tibetan plateau. The main sliding boundary between the Indian and Eurasian tectonic plates is called the Main Himalayan Thrust, and this is where we believe these two largest earthquakes occurred. These earthquakes are therefore "helping" India move further underneath Tibet.

The danger of this area has been long recognized within the geophysical community. A previous large earthquake occurred just to the southeast along the same thrust in 1934. Here is a historical map of shaking intensities from the 1934 quake with the location of the M 7.8 Gorkha quake indicated by the white box.

The Gorkha earthquake was recorded nicely with InSAR. InSAR is a satellite based method in which radar is swept over an area before and after an earthquake, and the two images are artificially "interfered" with each other, producing interference fringes that outline changes between the two time periods. The InSAR results can be viewed here and indicate that approximately 4-5 meters of slip occurred in an oblong patch.

The recent M 7.3 earthquake could be considered an

... keep reading on reddit ➡

👍︎ 250
📰︎ r/science
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📅︎ May 12 2015
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Help with tectonic plates

So I'm working on some worldbuilding stuff and I've sketched out the tectonic plates for the planet as well as their general direction of movement. You can see the map here. I'm now at the point of trying to determine what's happening at every plate boundary, but I find myself scratching my head in a lot of these cases as I feel like a lot of these are meeting or spreading at right angles to each other. So if you could help me figure that out that'd be awesome.

As you can see I've started to do some of the work, and the key for the work I've done is as such:

Red: diverging boundary

Blue: subduction zone

Green: transform fault

Purple: converging boundary leading to orogeny

Anyway, any and all help would be greatly appreciated. :)

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📰︎ r/geology
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📅︎ Jan 20 2020
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Strange Neotectonics of the Mackenzie Mountains and Northern Canadian Cordillera

If you check a map of seismicity for Western North America, you might notice that besides the predictable seismic activity of the southern and central Cordillera, there is an anomalous region of relatively high seismicity associated with its northeastern limits, the Mackenzie Mountains, the Franklin Mountains, which represent the limit of the active Mackenzie fold and thrust system, and the Richardson Mountains to their Northwest, where the thrust sense of deformation gives way to transpressional, right-lateral strike slip movement at the far western edge of the region.

Besides being hundreds of kilometers from an active plate boundary, the active plate boundary itself is largely of the strike slip kind, and it’s in the wrong direction, representing relative movement northwest of the pacific plate along the Queen Charlotte and Fairweather faults. Convergence begins at the active collision of the Yakutat block and the rapidly rising St Elias mountains, and flat-slab subduction west of that, dipping towards the interior of Alaska and Denali, but again, the direction is to north/northwest, something close to 90 degrees west of the direction of shortening in the Mackenzie Mountains far to the Northeast.

Yet the earthquakes and geodetic data show that the Mackenzie mountains are actively undergoing shortening.

I have found only one paper that addresses this strange situation directly, and they implicate “strain transfer” due to collision of the Yakutat block as a continental (well, oceanic plateau) indentor as the tectonic driver in this situation.

Other complexities to consider are:

1.) Likely subduction or slab-edge flow driven active volcanism in the Wrangell Volcanic Belt, between the Yakutat block and the Mackenzies (but again the slab is to the west, dipping NW, there is no slab dipping under Canada towards the northeast.)

2.) Likely incipient continental rifting in the interior of Northern BC and southern YT, as evidenced from geochemical signatures associated with the large, active Northern Cordillera Volcanic Province, relatively thin crust, and total lack of seismicity in the region. So despite active subduction in Cascadia to the south, west-northwest movement of the North American plate, and apparent shortening to the Northeast in the Mackenzie mountains, the region in between is in active extension. Perhaps some kind of tectonic escape situation, where northern interior BC is being squeezed apart along strike slip faults (Queen Charlott

... keep reading on reddit ➡

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📅︎ Feb 19 2020
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Okay, so how on earth did New Zealand form?

I'm looking at the information available to me, and New Zealand forming, as I understand it, involves it breaking off of Australia and sinking into the ocean. This confounds me for several reasons.

1: I see no rift valley. It's my understanding that when continents break apart, you get a rift valley, which forms into an ocean. Now, I see no oceanic ridge between New Zealand and Australia that may have formerly been a rift valley.

2: How is New Zealand not on its own plate? It's made of continental crust, and separate from New Zealand through a process I can only assume involved rifting. Wouldn't this result in it being on its own plate? Instead, this mass of continental crust is somehow over a convergent boundary where two bits of oceanic crust meat. How does this work? This doesn't make sense to me.

3: It's on a convergent boundary, but the sunken continent isn't outlined by subduction zones? If two bits of oceanic crust are ramming together around New Zeland, which is made of continental crust, why isn't the crust subducting under all of Newzealand?

Now, I'm assuming I'm missing some major information here, or there are some mechanics here that I just don't understand or know about, because this whole situation pokes so many holes in my understanding of plate tectonics and how continental crust moves, that it boggles me and makes me question if I know anything at all. Someone, please explain this mess to me.

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📰︎ r/askscience
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👤︎ u/jaxlov
📅︎ Feb 13 2019
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Tectonic Plates Are Actively Spreading In all of the following EXCEPT:

A. Rift Zones

B. Sea-Floor Spreading Areas

C. Subducting Plate Boundaries

D. The Mid Ocean Ridges

(I think it's C, But I really don't know. I need a second opinion)

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📅︎ Oct 31 2020
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questions about plate tectonics

Hi,

I'm a programmer, and I have a high level goal of writing a world generator that makes a world map which I will use later for a game. I want to do it with a rough simulation of plate tectonics. I wanted it to be somewhat consistent with reality where it makes sense, but its ultimately for fun so I don't need to get every little thing right. For example, I am not concerned with simulating the mantle for its own sake. But I do want boundaries to form in plausible places. I have occasionally gone on spurts where I scour google/reddit etc and learned a bit. I have a very basic mental model of how things work, but there are spots where I am unclear and I may be wrong in what I know.

The way I understand it is that tectonic plates are like conveyor belts that are moving from divergent boundaries towards convergent boundaries, following a cell pattern. Depending on the composition and thickness of the plate, its speed may very, and it can stretch or bunch up as it travels.

I realise that there are all sorts of different types of rock, but I am simplifying that part of it to continent and plate.

The thing I am most unclear about is the general motion of the plates. Looking at 2d projections makes it very hard to see what the motion of the plates really looks like as a whole. And I know there is rotation, and its not as simple as going from point a to point b over a long period of time. The general motion of an individual plate isn't something I get yet. Or how "fluid" they are.

The continents seem to make sense as much as I need them too. They just ride the conveyor belt, and bunch up or tear apart based on what they are riding. And there is some rate of creation, "destruction", and a constant rate of erosion. If there is a point I am missing here I don't know it. I think I know enough on this to do what i need to do.

The biggest question mark for me is the boundaries themselves, and how they move and change over time.

I can see stability in divergent boundaries. But convergent boundaries seem unstable. One plate is sinking, the other is not. Or can it switch? So does that mean that the subducting plate is slowly being covered by the other plate? Does that mean that a convergent boundary is moving towards one of the plate's divergent boundaries? That makes sense from a surface perspective, but less so when thinking of plates as the top of a convection cell.

Aside from the above I don't know what else might drive how these boundaries change over tim

... keep reading on reddit ➡

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📰︎ r/geology
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📅︎ May 16 2020
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Why does most subduction occur in the Pacific.

Hello, I have recently switched my major to Geology, and I am just trying to learn as much as possible. Right now we are learning about different plate boundaries.

I don’t understand why there are no trenches and Lithospheric subduction on say the coast of Africa. Why doesn’t every continent have a trench alongside it, like the Peru Chile trench for example. The crust created at mid ocean ridges has to be gotten rid of somehow, so why does it not sink into the mantle all the time (at ocean-continent convergence zones) I’ve heard that the Atlantic Ocean is growing while the Pacific is shrinking. I just can’t wrap my head around why exactly this is happening and the lithosphere is not subducted along all oceanic-continental margins.

I’ve heard that the crust formed in the Atlantic replaces all other oceanic crust, but why does this crust push against continents rather than subduct under them.

I hope this isn’t a very dumb question, it’s just confusing because to me it makes way more sense having the crust formed along the crests of the mid ocean ridge which is then eventually pushed to a continent in which the oceanic lithosphere subducts into the mantle in a continuous cycle and this seems to be how to book explained it.

I’m a beginner pretty much so forgive my stupidity if this is really obvious.

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📰︎ r/geology
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👤︎ u/Keiono12
📅︎ Jan 26 2020
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Is there a build up of sediment/material along subduction zones or is the entire plate and everything attached to it subducted?

For example, imagine an oceanic plate in a tropical region abundant with reefs/corals subducting underneath a neighboring continental plate. Does all of that reef material and surface sediment that has not been lithified get subducted as well, or is there evidence of it "scraping" (for lack of a better term) off the top of the subducted oceanic plate and building up against the continental plate above the actual boundary where subduction occurs? What do these places where subduction actually occurs look like?

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📰︎ r/askscience
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📅︎ Jan 24 2019
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Simple (I think?) Trigonometry in Spherical Geometry / Coordinates Question

Hello,

I'm a geology student and currently working on an independent research project wherein I need to use some trig and spherical geometry; maybe a tad bit of calculus too.

To try and better understand what Im trying to do I'll need to explain a tad bit of geology background:

The question I'm trying to ultimately work out is this: How much has a tectonic plate subducted at a specific location (a point) in the past 130 million years?

Subduction is where one tectonic plate collides with another and results in one of the plates being pushed down underneath the overlying colliding plate. I'll try to hopefully make this more relatable/understandable with an analogy: this process would be like being in a pool with your friend and you and he push two boogie boards (the tectonic plates) together. One of these boogie boards will end up dipping below the other and going underwater, aka being subducted. If you pushed your Boogie board at a constant velocity while your friend held his still, you could predict how much of your boogie board is underwater at a given time (relative to the position of his fixed board) with some basic math.

The math can be spiced up a bit by changing the angle you are pushing against your friend's boogie board. Instead of pushing directly against your friend's board, you push at an angle to his fixed board. Your board is still being pushed underwater, but now with a decreased velocity as you now have to resolve the magnitude of the velocity into separate components. Still not too bad.

Now, here's where I get confused. In my analogy above, this could be calculated using cartesian coordinates, however, the Earth is a Sphere and I dont believe the math I'd use to model "how much my boogie board has subducted in the past 130 million years" would be quite the same. Could someone help me out with the trig (& possibly multi-variable calculus) needed to calculate this?

I have this data to work with:

Velocity Magnitude (y-axis) vs Time (x-axis) (All these are relative to referenced point (lat, long) on the boundary of the subducting Plate)

Velocity Azimuth vs Time

Angular Velocity vs Time

Lattitude vs Time

Longitude vs Time

Velocity Colattitude vs Time

Velocity Longitude vs Time

Thank you very very much for your time and help!

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📰︎ r/learnmath
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📅︎ Nov 25 2019
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DayZ Geological Survey

I am near graduating with a B.S. in Geology and I enjoy playing dayZ SA on occasion (230hrs.) Over time, I have always been thinking about the geology of Chernarus. It wasn't until recently that I have decided to take a different approach to playing the game; one that involves less killing, looting, From now on, I will be travelling the map and studying the geology that I see. I will post my observations on here. Side note: Most of them will be me pointing out things that are geologically in-accurate, but that doesn't mean I'm complaining, they are just suggestions if anyone would care to change them.

Some first observations after playing for a bit today:

  1. The water level in the wetlands near Rify(shipwreck) needs to be lowered to match sea level. (136,042;DayZDB)

  2. Unless sea level has risen dramatically over recent geologic years, the shores of the whole continent need to exhibit some sort of a fining, and/or sorting gradient in a basinward (towards sea) direction. [Observed in every beach I have been to.]

  3. Over the whole course of playing DayZ, my large-scale interpretation of the geology would be that Chernarus is positioned at a rather tectonically-inactive, continental margin. Although no observed subducting plate-boundary, the various batholiths/plutons throughout the area may have an unknown origin within the mantle. It is apparent that weathering/erosional processes have continued for a long time (enough soil to support plant growth, river valleys, etc.). Due to nature of DayZ being a game, the lithologies can only be assumed to be felsic metamorphic/igneous rocks.

These are just some observations right now. If anyone has any of their own, I would be very interested in seeing what they are. Cheers, and be careful of those zombies.

-TheRockSurvivor

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📰︎ r/dayz
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📅︎ May 01 2014
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