2985: Craters

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Craters

Title text: It's annoying that the Nastapoka Arc isn't a meteor impact crater, but I truly believe that--with enough time, effort, and determination--we could make it one.

Explanation

This explanation may be incomplete or incorrect: Created by a LITTLE PRINCE ON A ROCK - Please change this comment when editing this page. Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks.

This comic uses a Venn diagram to classify large circles on the ground into meteor impact craters, "weird circles on the map", and both.

Venn diagram section	"Crater"	Explanation
Meteor Impact Craters	Northern Yucatan Peninsula	This refers to the famous Chicxulub crater, where an asteroid ~10 km in diameter struck the Earth 65 million years ago and caused the extinction of non-avian dinosaurs.
	Charlevoix Region	Astroblème de Charlevoix, or Charlevoix impact crater. A 400 million-year-old, 54 km-wide crater which lies partly in the waters of the St. Lawrence River and stretches halfway between Quebec City and the mouth of the Saguenay River.
	Sudbury Basin	A large valley in Ontario, formed by an impact 1.849 billion years ago.
	Chesapeake Bay	A crater buried beneath the mouth of Chesapeake Bay, where an impact occurred around 35.5 million years ago.
(Venn diagram intersection)	Lake Manicouagan	A large ring-shaped lake in Quebec, formed about 214 million years ago.
	Lonar Lake	A circular lake in the Deccan Traps basalt of India, formed approximately 570,000 years ago.
	Clearwater Lakes	A pair of lakes next to each other in Quebec, one formed 460-470 million years ago, the other formed closer to 286 million years ago.
	Meteor Crater	A crater in Arizona about 1.2 km across where a meteor hit around 50,000 years ago.
Weird Circles on the Map	Nastapoka Arc	A section of the shoreline of southeastern Hudson Bay that's almost a perfect circle.
	Crater Lake	Most likely reference is the Crater Lake that's in Oregon, the deepest freshwater body in the United States, which formed in the caldera of Mount Mazama after it exploded around 7700 years ago.
	Stonehenge	Stonehenge is a megalith on the Salisbury Plain in England which is famous not only for its historical significance and impressive scale but for stories surrounding its creation and purpose.
	The Great Blue Hole	A large, nearly-circular marine sinkhole off the coast of Belize.
	Delaware's northern border	The Twelve-Mile Circle comprises several surveyed arcs that define the borders between Delaware and Pennsylvania, and between Delaware and bits of Maryland and New Jersey. These arcs and Stonehenge are the only manmade features in this comic.

The title text refers to the Nastapoka Arc, a section of the Hudson Bay shoreline that is almost a perfect circle. This was most likely caused by continental plates crashing into each other rather than a meteor impact. However, Randall believes that it CAN be an actual meteor impact site with enough dedication: he wants to redirect an asteroid into Hudson Bay, which is a bad idea^{[citation needed]}. There is no efficient way to artificially direct asteroids towards Earth, let alone ones large enough to make the appropriate size hole. The Double Asteroid Redirection Test (DART) slightly changed the orbit of one asteroid around another by slamming a spacecraft into the asteroid; doing any more substantial redirection would require applying large impulse to an asteroid, which has never been done. Moreover, the precision required would be a massive obstacle: a small variance in timing or angle would make the asteroid hit Earth in the wrong manner, at the very least creating an improperly matched hole (for size and shape), with the most likely outcome being to miss the original feature entirely. There is also the potential to slam into nearby populated areas, but some historic circular features are themselves populated so would suffer directly in the case of a perfect impact. Attempting to do so would be costly^{[citation needed]} and potentially cause massive devastation.^{[citation needed]}

This idea of directing an asteroid to directly impact the Earth is on some level an inversion of disaster movies like Armageddon, where an asteroid is landed on to destroy or deflect it. Armageddon has been discussed before on xkcd.

See also

List of impact structures on Earth

Transcript

This transcript is incomplete. Please help editing it! Thanks.

[A Venn diagram with two circles.]

[Label above left circle:]

Meteor Impact Craters

[Label above right circle:]

Weird Circles on the Map

[Left circle items (Meteor Impact Craters):]

Northern Yucatan Peninsula

Charlevoix Region

Sudbury Basin

Chesaspeake Bay

[Right circle items (Weird Circles on the Map):]

Nastapoka Arc

Crater Lake

Stonehenge

The Great Blue Hole

Delaware's Northern Border

[Middle intersection items:]

Lake Manicouagan

Lonar Lake

Clearwater Lakes

Meteor Crater

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Discussion

Delaware/Pennsylvania Arc

The Delaware/Pennsylvania arc is a circle, sure, but so is every other allegedly "straight" line on the map. The 49N parallel looks like a straight line on some projections, but a polar projection shows that it is clearly a circle around a point on the Earth's axis. The Delaware/Pennsylvania arc is only unique for NOT being aligned with the axis. 172.71.102.20 19:07, 13 September 2024 (UTC)

The "Delaware/Pennsylvania arc" has a long and juicy history. Not a circle. Twelve-Mile Circle Signed- --PRR (talk) 20:36, 13 September 2024 (UTC)

True about map projections, but the Venn section title here does say *Weird*. The Delaware/Pennsylvania arc is indeed "weird"; few other such arcs are found in regular map content, and the original story for it is indeed uncommon. Great Circle Parallel latitude "arcs" aren't weird in either way. 172.68.34.64 20:52, 13 September 2024 (UTC)

North-South lines are great-circle arcs, but non-equatorial East-West lines - as well as many diagonal ones - are minor-circle arcs (is that the right term?), just link the 12-Mile Circle. (Let's see if this retains my IP address from my top post.) 172.70.46.109 21:29, 13 September 2024 (UTC)

Right you are! 172.68.34.64 23:00, 14 September 2024 (UTC)

Great Blue Hole

There are two Great Blue Holes, one in Belize, one in Dahab, Egypt (Red Sea). 172.71.102.20 19:11, 13 September 2024 (UTC)

Recent Google Maps discovery

This may be inspired Joël Lapointe's very recently announced discovery of a 15km-diameter "pit" he found near Marsal Lake (Quebec) using Google Maps. "He saw a suspicious pit on Google Maps. Experts say it could be a crater from an ancient space rock" 172.69.64.185 20:10, 13 September 2024 (UTC)

---

man, why are so many of these in Quebec? does it have a natural meteor/circle magnet? 172.68.174.232 01:11, 14 September 2024 (UTC)

The Laurentian Shield is a craton (therefore craters not deformed into unrecognisebility by tectonic action, and not hidden under thick sedimentary cover). Furthermore the ice sheets scraped off what sedimentary cover there was. 162.158.74.49 18:02, 25 September 2024 (UTC)

Parce qu'on y parle français. 172.69.71.68 12:39, 14 September 2024 (UTC)

New Column

I'm thinking about a new column or two: GPS coordinates (with an Open Earth link?) and a satellite image, or something. 172.71.102.76 03:27, 14 September 2024 (UTC)

The table seems incomplete without something like that. 172.69.34.172 22:50, 14 September 2024 (UTC)

Meta Reference: Venn Diagram Double Crater

No comment yet on the fact that the two circles in the Venn Diagram refer to craters and circles... 172.71.102.53 01:32, 15 September 2024 (UTC)

Geographic bias by meteorites or Randall?

Boy am I happy that I don't live in North or Central America, where 11 out of 13 "craters" are located... Mumiemonstret (talk) 07:44, 15 September 2024 (UTC)

Maybe over here (rightpondia, oceania, down-under and the cradle of humanity itself), we just cleaned them up easier (or messed them up badly) so they were less obvious. (c.f. Nördlingen.) Y'all over thataway, however, haven't had time to do anything too drastic to obscure them. ;) 172.70.163.48 14:10, 15 September 2024 (UTC)

Haha, yeah, that was also my first thought when I googled the places I didn't know: very America-centric by either Randall or meteorite or other circle-creating entities... And even the other 2 places are in English speaking places (yes, I know English isn't the official language of India, but still one of the most common)--Lupo (talk) 04:28, 16 September 2024 (UTC)

I am tickled pink that two significant items in my life appear adjacent in this diagram: Stonehenge, and Crater Lake. My company name is Stonehenge (and I've been to the real rock pile a few times), and I'm a native Oregonian, using Crater Lake as my video-call background. RandalSchwartz (talk) 22:02, 15 September 2024 (UTC)

Crater Lake

So we're not going to talk about Crater Lake not being an actual crater? 172.69.134.107 (talk) 22:12, 16 September 2024 (please sign your comments with ~~~~)

"Crater Lake (Klamath: Giiwas)[2] is a volcanic crater lake..." 172.70.91.2 23:48, 16 September 2024 (UTC)

no monday comic

silly randall 172.70.86.146 07:17, 17 September 2024 (UTC)

nvm 141.101.99.136 08:28, 17 September 2024 (UTC)

What's with the excessive use of headers in this chat?

Sinkholes

Kingsley Lake is located Southwest of Jacksonville, FL and directly East of Starke, FL, on the grounds of Camp Blanding. If you look at it on Google Maps, you will notice that it is pretty much perfectly round. You would think that this was a meteor impact, but in fact it is just a really large sinkhole. Camp Blanding dates back to World War II when it was being used as a training camp for the Army and also as a POW camp for captured German soldiers. Foozini (talk) 04:37, 19 September 2024 (UTC)

Meteor impact craters???

Meteors don't leave craters. Meteorites do. Just saying. --172.68.110.188 20:23, 19 September 2024 (UTC)

At what point does a meteor become a meteorite? Arguably when it (or its fragments) are found laying there. If so, while it is still undergoing lithobraking then it is still a moving meteor.

The alternative is that:

• an asteroid (or comet fragment, etc) in vacuum is an asteroid (or comet fragment, etc)
• in an atmosphere, it is a meteor (with the possibility of skimming and becoming its 'vacuum self' once more)
• in (or on) the solid surface, it is a meterorite (and permanence of this state might not be guaranteed, if dynamic)
• this begs the existence of a term that (by rapidly researching the possible back-sources) might be something like "metydor" or "metanao" that relates to such a body currently in/passing through water (the latter coming from possible alt-historic scholarly adoption and anglicisation of the similarly old Greek word for "swim", to contrast with the aerial suspension of a meteor, though the former is just "water" itself, much as the "-eor" element is related to the word that became "aerial", i.e. "of the air")... Though there might be arguments for something like "meteoretis", also, if you go down a different rabbit-hole.

Doubtless there are countless other justifiable interpretations (and alternate linguistic allocations), but these are my own main (and opposing) two. 172.70.160.231 08:40, 20 September 2024 (UTC)