3171: Geologic Core Sample

Geologic Core Sample

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Title text: If you drill at the right angle and time things perfectly, your core sample can include a section of a rival team's coring equipment.

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Explanation

This is one of 52 incomplete explanations: This page was created BY A RIVAL GEOLOGY TEAM. Don't remove this notice too soon. If you can fix this issue, edit the page!

This image presents a core sample taken by a slightly chaotic team of geologists.

A core sample is a cylindrical piece of something's core, in this case the rock of Earth's crust, obtained with special drills in order to see the layers within. In typical xkcd fashion, the core sample depicted here contains a mix of real rocks found in core samples alongside many humorous or fictional additives. In addition it's shown that the coring drills have hit many, many obstacles on the way down they really shouldn't have impacted, culminating in a punchline the geologists have drilled straight through the Earth to the opposite hemisphere, far deeper than any core sample could be taken in reality.

Contained within it are fairly normal ground matter such as "topsoil" and "granite" but also such things as "bottomsoil", which has no IRL parallel, parts of subway cars, arms of a spelunker most likely amputated by the sample, netherrack (a dark red stone appearing in the Nether in Minecraft), a "balrog" wing (referencing a fictional animal from Lord of the Rings which first made an appearance in xkcd in 730: Circuit Diagram).

After a discontinuity in the diagram, that would cover whatever might appear having driven through the core of the earth, there is a reversal of the more 'standard' layers and then some equally nonstandard layers. These indicate that it has tunneled up into the home of someone else, starting with cement (the foundation), floorboards and carpet, then their posessions.

While still on the side that is heading down, it also mentions other rocks that are "basically granite". As in the idea that many rocks are similar, but are called "diorite" or "andalite". Diorite is a real rock, but an Andalite is an alien from the Animorphs book series, which Randall enjoys and has referenced before.

In reality, only about 15% of the earth's land surface is antipodal to other land, making this sample less than "typical". If one were to start on land and drill all the way through the center of the earth to a point on the other side of the world, one would be much more likely to have the sample terminate in an ocean than on land, much less in someone's house. Though considering that title text mentioned drilling at an angle, that other side might be not at the antipodal point.

The title text humorously refers to a "rival team" and their coring equipment — implying that (with the correct angle) you can meddle with their own coring experiment. This is, outside of cold war-type pettiness, not considered a constructive approach to science.^{[citation needed]}

Transcript

This is one of 27 incomplete transcripts: Don't remove this notice too soon. If you can fix this issue, edit the page!

[This shows a drill sample with various labels, in order from the top of the panel toward the bottom.]

• Topsoil
• Till
• Granite bedrock
• Bottomsoil
• Roof of subway car
• Floor of subway car
• More granite
• Municipal water main
• Slightly different granite
• Piece of screaming spelunker's arm
• Cool crystals with no resale value
• Mangled fragments of drillbit from previous attempt
• Some boring intrusive rock that's basically granite but has a name like "diorite" or "andalite" that you always have to look up
• Netherrack
• Balrog wing

[At this point, there is a discontinuity indicating that some layers have been omitted. The sample then resumes:]

• Granite
• Topsoil
• Cement
• Floorboards
• Carpet
• Possesions of a confused and angry homeowner in the other hemisphere

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Discussion

F1R5T P0ST Slothscript (talk) 23:51, 21 November 2025 (UTC)

How do I add a category? It needs to be in the LOTR category. (Wow it’s hard to edit this thing on a phone) Kirinhatchi (talk)

is netherrack a typo? 151.197.190.53 (talk) 00:24, 22 November 2025 (UTC) (please sign your comments with ~~~~)

No, it's an extremely weak, dark red rock from Minecraft. RadiantRainwing (talk) 00:39, 22 November 2025 (UTC)

andalite is not a rock it's an alien from Animorphs which the author is a fan of. Maybe I'll add it to the Animorphs category page Whoservelt (talk) 00:28, 22 November 2025 (UTC)

They’re just normal rock types, so perhaps not, but I was wondering if the back-to-back references to granite and diorite is a secondary Minecraft reference, since they were added in the same update (which I always associate with them in general.) KelOfTheStars! (talk) 01:23, 22 November 2025 (UTC)

I think it IS another Minecraft reference. Along with granite and diorite, there’s a third in that triad: andesite — which is spelled and pronounced similarly enough to “Andalite” that the two could quite possibly be conflated, especially by someone who is familiar with the latter and “always has to look up” the former. 2a04:4e41:3521:69d6::1d21:69d6 (talk) 01:44, 22 November 2025 (UTC) (please sign your comments with ~~~~)

Well, it's 'andalite' in the comic, not andesite. I think that's just a passing reference. --DollarStoreBa'al^Converse 02:29, 22 November 2025 (UTC)

It's been a long time since I Minecrafted, but I don't recall any (stock) inclusion of anything so realistic. Raw 'generic' stone (which became cobblestone once mined, unless it was an ore-holding version), sandstone, obsidian (which I'd usually cast) and the indestrutable bedrock - in the 'normal' world. Netherack (I keep wanting to type "nethack"!) in the Nether and maybe something else (other than the general igneous theme, fire and hostiles) ...glowstone? I know there are (were) 'real rock patches', as with many other mods, but I hadn't heard of this being put into vanilla editions (Bedrock, or whatever). Whether it's happened since the Ender got put in, I don't know. I was playing (solo-survival mode, mostly) when there were Endermen, but not yet their own domain for them/the dragon, and basically forgot about it before Microsoft took it on (then had too many other new time-sinks to even consider selling my soul to them)...

But something like Dwarf Fortress does have plenty of rock-types (plain 'granite', but also diorite, gabbro, slate, limestone, mudstone, etc, etc, etc, even before getting to ores and gem clusters), for longer even than Minecraft had been around, and I linked into that where I thought appropriate. 82.132.236.186 17:26, 22 November 2025 (UTC)

You've not minecraft in a long time then friend, it's been over a decade since Endermen were added. Here are some more stone types in vanilla minecraft other than the ones you listed: Granite, Andesite, Diorite, Sandstone, Red Sandstone, Tuff, Deepslate, Calcite, Dripstone, Basalt, Blackstone, and End Stone. 199.247.247.123 19:20, 22 November 2025 (UTC)

As another long-lapsed minecrafter, that's news to me. (Could I colour stone, back then, or was that just wool blocks and maybe some modded-in 'concrete'?) Also reminded me more of DF stones, though, there being a lot of those, and MC looks like it's still not quite as complexity. I love being able to build entire castles in olivine, or cinnabar/whatever's plentiful enough (and not ore/flux, or the limited amount best saved for other purposes like colour-coded magmasafe floodgates/levers), without 'cheating' by applying my own hues to them. Mind you, I also prefer pre-Steam ASCII-style (vanilla) DF, as well, easier to understand, sometimes, than trying to understand some of the artwork. 2.98.77.121 20:08, 22 November 2025 (UTC)

Concrete is now an actual thing in minecraft. It's color is basically solid, So it's great for building. --DollarStoreBa'al^Converse 00:12, 23 November 2025 (UTC)

Do we make this a table? This comic seems perfect for a table. Maybe 'layer', whether it's real or not, and explanation? --DollarStoreBa'al^Converse 01:36, 22 November 2025 (UTC)

I'll try to work on a a table (given that someone else doesn't beat me to the chase). Also-what happened to your sig? 42.book.addict^{Talk to me!} 06:31, 22 November 2025 (UTC)

I was pondering a ";term:definition" approach, and someone beat me to it (but without the definition-indent) and I ran my changes with it. I don't think a table would need more than two columns (excluding "Real?", being "Yes", "No" or "Technically Yes/No, but..."), so, with the predicted division of vertical space in a table, I think I'd stick with the header+explanation of the ";:" method. (Can always add a Real/Not Real {{Yes}}/{{No}}/{{Maybe}}-like appending/prepending note to the term-header...) It's not really going to need sortable-table use, etc. 82.132.236.186 17:26, 22 November 2025 (UTC)

Should reference somewhere that Balrogs having wings is controversial to begin with (see here)[1] 2601:241:8002:3E0:89D3:137:DFC1:D5B4 04:41, 22 November 2025 (UTC)

Hadn't read this, when I puut my own thing about it in there. The actual "did they have wings?" bit, in the Balrog page I linked to a section of, is buried within a multiparagraph section, so maybe your link is better (or a better one in that part, straight-link Balrog on the first mention for the general wikipedia entry).

Certainly, when I was young (long before Wikipedia, and indeed the Web... Not sure when alt.fan.tolkien started, but I didn't have usenet access before I had academic internet access, but it was already an FAQ when I finally got into that scene), the questions were:

1. So, did a (or 'the', or any, depending on tye context) Balrog have actual wings?
2. If they did, why? Given they were subterranean denizens? (Probably not the exact words, maybe "...living underground".)
3. So how could it be made to fall like that? (Typical answer: "A wizard did it"... Namely Gandalf kept it falling/distracted. Because that was the point.)

...I may check to see if the collected wisdom of the current ubiquitous fan-led website has any better answers than we would come up with, after our countless geek-hours of discussion after/before/during tabletop RPGing (even if it wasn't LOTR-based, someone could easily have mentioned the balrog, in the context of a viking attack over a narrow bridge, or whatever). 82.132.236.186 17:26, 22 November 2025 (UTC)

Balrogs are not naturally subterranean. They're Maiar, just like Sauron and Gandalf. They used to fight in wars and do other evil stuff on the surface. DL Draco Rex (talk) 15:33, 23 November 2025 (UTC)

Actually, coring previous drilling equipment can happen. The southern German town of Staufen suffered a geothermal drilling gone wrong (they inserted ground water into anhydrite, which swelled, causing the town to rise). During the investigations, the original drilling equipment was hit in the new core, showing the errors made in the first place. 2001:16B8:A875:DC00:3068:165E:B396:DE72 07:33, 22 November 2025 (UTC)

Side comment on the header saying "typical": coming to the surface on land instead of water is extremely unlikely, as we were taught years ago by Ze Frank's "If The Earth Were a Sandwich" video series. Look it up. Jonesey (talk) 16:24, 23 November 2025 (UTC)

The explanation talks about how the Nether is essentially Minecraft hell - it might be worth mentioning how the comic might be referencing going so deep you find hell. That might also coincide with the Balrog wing (do they live in hell?), something something digging too deep, but I lack the requisite LOTR knowledge to make that connection for real R128 (talk) 13:50, 24 November 2025 (UTC)

Also, they've ended up coring another person's house, and as we all know, hell is other people...

Oh, and there's a bit of water main in there, and the main is, of course, high water. 82.13.184.33 14:30, 24 November 2025 (UTC)

Probably the Kola Superdeep Borehole should be mentioned.Rps (talk) 16:44, 24 November 2025 (UTC)

This also has a related comic 1330: Kola Borehole --134.102.219.31 16:53, 24 November 2025 (UTC)

Switched out the balrog reference in 730: Circuit Diagram for the one in 3141: Mantle Model, since the former felt way too indirect of a reference to be relevant here, and the latter is a lot more directly tied to geology.KelOfTheStars! (talk) 19:22, 24 November 2025 (UTC)
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