stagnant waters made us uneasy with their silence

April 7, 2021 10:55 PM

A geologist summarizes the legends and science of bottomless pits, bogs, and lakes at Spooky Geology.

(Via the Squaring the Strange podcast.)

posted by eotvos (22 comments total)

(Note that the bit about falling for twenty hours and getting trapped in the center of the Earth is very clearly incorrect in several ways. I hope the rest of it is more accurate, but I'm no expert.)
posted by eotvos at 10:59 PM on April 7, 2021 [3 favorites]

Terminal velocity of a human body in air is supposed to be ~200 mph, so 20 hr. X 200 mph = 4000 mi., which is the approximate radius of the Earth, but that doesn't take into account that the air in the hole would get denser as you go down, and the acceleration due to gravity would be less, since you experience no net force or acceleration from the shell of Earth farther away from the center of the Earth than you are at any given moment in your fall.

If the Earth were as airless as the Moon, it would take 42 minutes (as I recall) to traverse any straight hole drilled completely through the Earth whether it passed through the center or not.
posted by jamjam at 12:44 AM on April 8, 2021 [3 favorites]

Terminal velocity of a human body in air is supposed to be ~200 mph, so 20 hr. X 200 mph.

Damnit. It never occurred to me that the hole was full of air. I withdraw my obnoxious comment. Thanks!
posted by eotvos at 1:17 AM on April 8, 2021 [2 favorites]

Your original comment that it was "very clearly incorrect in several ways" is perfectly true, though.

I was just trying to get a kind of forensic sense of the path the author might have walked to get to the ridiculously unphysical 20 hours number. Failing to take into account increasing density of the air and the decreasing force of gravity along the way makes 20 hours laughably inaccurate even in the totally unrealistic context of a scenario where a hole to the center of the Earth could exist.
posted by jamjam at 2:41 AM on April 8, 2021 [2 favorites]

So much for my "only for spherical cows" rebuttal.
posted by zengargoyle at 2:56 AM on April 8, 2021 [1 favorite]

Bonus: How to mathematically calculate a fall through the Earth. It's very interesting.
posted by zengargoyle at 3:06 AM on April 8, 2021 [1 favorite]

Marie Bonaparte noted the idea of “unfathomable” was applied to still waters, not the ocean or rivers. The ocean, while clearly deeper, at least moved, ebbed, and flowed. Rivers also were moving and occasionally revealed their bottoms. But stagnant waters made us uneasy with their silence.
Today I realized the literal meaning of unfathomable. Neat!
posted by travertina at 3:40 AM on April 8, 2021 [6 favorites]

The bottomless pit from The Flintstones episode Dr. Sinister scared the hell out of me at age 5.
posted by thelonius at 3:42 AM on April 8, 2021 [1 favorite]

Well the author of the main linked piece does link to an article that assumes an air-filled shaft through the Earth (from pole to pole, to avoid Coriolis forces). However, that article itself seems rather arm-wavey, even allowing for the necessary assumptions and simplifications. For instance, the author notes that pressure will increase, but does not indicate by how much. Some online searching throws up several attempts to answer this problem, which note that the pressure will be so high that you cannot just assume that air is simply compressible any more. 'Hundreds if not thousands of atmospheres' seems a likely answer, in which case pressure alone won't be your problem - adiabatic heating will.
posted by Major Clanger at 4:18 AM on April 8, 2021

pressure alone won't be your problem - adiabatic heating will.
I have lots of problems, what's one more?
posted by thelonius at 4:31 AM on April 8, 2021 [5 favorites]

In this great land there are many pits, but none more bottomless than the Bottomless Pit which you can see here is bottomless.
posted by RonButNotStupid at 4:55 AM on April 8, 2021 [1 favorite]

Not mentioned: meromictic lakes, whose layers never mix, are sometimes called “bottomless” because they in fact have no distinct limit—the line is blurred by increasingly dense sediment and organics.
posted by kinnakeet at 5:03 AM on April 8, 2021 [4 favorites]

Some online searching throws up several attempts to answer this problem, which note that the pressure will be so high that you cannot just assume that air is simply compressible any more.

This represents such a miserable failure at The Vision Thing.

Once our engineering team has built a liner for the walls of our hole from such a high grade of unobtanium as to resist pressure sufficient to solidify iron at 6000K, it will surely be very little extra trouble for them to retrofit air handling and heat transfer systems capable of doing whatever we want with the air density and temperature inside it. And they'd better get on with it if they want to keep their jobs. Elon has already assured investors that the company expects to have a shuttle service running this route commercially available 3Q 2023.
posted by flabdablet at 5:47 AM on April 8, 2021

An artificial bottomless pit: A drilling error drained Lake Peigneur into a salt mine, 1300 feet below. Including 11 barges and a tugboat. Youtube link.
posted by jjj606 at 6:01 AM on April 8, 2021 [4 favorites]

I once worked with the driller who was on the brake when that happened! He was never allowed to forget it.
Also, the thread needs a mention of The Strid - a bucolic death-stream in Yorkshire.
posted by thatwhichfalls at 6:11 AM on April 8, 2021 [7 favorites]

pressure alone won't be your problem - adiabatic heating will.
I have lots of problems, what's one more?

I got ninety-nine problems but adiabatic heating ain't one.
posted by Halloween Jack at 6:20 AM on April 8, 2021 [4 favorites]

... and in another dimension... "Mystery Flesh Pit National Park"
posted by rozcakj at 6:24 AM on April 8, 2021 [2 favorites]

Also, the thread needs a mention of The Strid - a bucolic death-stream in Yorkshire.

I thought of the Bolton Strid too; not to mention Bushman’s Hole (previously on MeFi).
posted by TedW at 6:49 AM on April 8, 2021 [1 favorite]

And Mexico would also like a place at this particular table: Zacaton.
posted by Insert Clever Name Here at 8:16 AM on April 8, 2021 [2 favorites]

Oh cool, time for Screaming.
posted by turbid dahlia at 5:40 PM on April 8, 2021

Anyone interested in the craters that started forming in Siberia around 2014 may find this article mildly terrifying:

Crater formed by exploding pingo in Arctic erupts a second time from methane emissions [Siberian Times, 29 March 2018]
posted by MrVisible at 6:50 PM on April 8, 2021

Holy crap, that article on Bushman's Hole was just intense. I will never go cave diving, ever.
posted by Halloween Jack at 9:19 PM on April 8, 2021 [1 favorite]