3171: Geologic Core Sample

2025-11-22T06:45:04Z

2607:FB91:1DCC:DB44:AC39:C132:6B0D:768:

{{comic
| number = 3171
| date = November 21, 2025
| title = Geologic Core Sample
| image = geologic_core_sample_2x.png
| imagesize = 493x789px
| noexpand = true
| titletext = 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.
}}

==Explanation==
{{incomplete|This page was created BY A RIVAL GEOLOGY TEAM. Don't remove this notice too soon.}}

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

A {{w|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 {{w|Minecraft}}), a "balrog" wing (referencing a fictional animal from {{w|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 "{{w|diorite}}" or "andalite". Diorite is a real type of igneous rock, but an Andalite is an alien from the Animorphs book series, which Randall enjoys and has [[:Category:Animorphs|referenced before]]. Perhaps Randall is "misremembering" the name of {{w|andesite}}, another type of igneous rock. This is likely another reference to Minecraft, which has all three rocks available in the overworld.

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}}

This comic may be intended as a criticism of standard conceptions of the geologic column, challenging the assumption that geological strata necessarily correlate with time. Just as it is obvious that the possessions of the confused and angry homeowner are not the oldest part of the sample, followed by the carpet, and so on, it is equally fallacious to assume that geological strata in real samples represent periods of time.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[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

{{comic discussion}}<noinclude>
[[Category:Geology]]
[[Category:Charts]]
[[Category:LOTR]]
[[Category:Animorphs]]
[[Category:Minecraft]]

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3171: Geologic Core Sample