We don't apPEAR to be moving... EarthCache
Hidden : 3/13/2019
Difficulty:
2 out of 5
Terrain:
1 out of 5

Size: Size: other (other)

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Geocache Description:


This is an Earthcache. There is no container to find.


Earthcache! Earthcache:) Earthcache? Earthcache.

What you can find is a Geology lesson!!!


By the end of this Earthcache we'll want you to have learned a little something about 'glacial isostatic adjustment' (also called 'post-glacial rebound') and its long-term effect on the midwest. Oh! And for you to be able to answer TWO questions! That's it!
Ok let's talk a little about glacial isostatic adjustment;
'Glacial isostatic adjustment' is best described as, the constant movement of land once buried under ice-age glaciers!
You may remember learning that during the most recent glacial period vast sections of North America were covered by extremely thick sheets of ice (like several thousand feet thick!) For millennia those sheets of ice got thicker and thicker and heavier and heavier. And a consequence of all that weight bearing down on the land beneath it, was that it all began to sink! Until....the ice started melting! And melting.... And melting!
And ever since those once massive glaciers have melted, the land under our feet has been MOVING!!! Now that might not seem like a big deal until you learn which way we're going!?!!
Here's a little graphic I customized to explain;
Post-glacial rebound
To put this in laypersons terms, think of a tube of toothpaste.
When you squeeze a tube of toothpaste in the middle, what happens?
The toothpaste squishes out of the middle and towards both ends, right?
Well what happens next when you squeeze that same tube from the end (like a normal person)?
The toothpaste goes back into the middle section, which flexes the tube back into its original shape!
Well that's exactly what is happening all over North America!
And where you are right now is somewhere between the middle and the end of that toothpaste tube! lol First we were flexed up (when the glaciers atop Canada got too heavy) and now we're being flexed back down (because the glaciers are all gone!)
So to bring this back into the earthcache, the land you're standing on right now is about to move back into its original position, under Canada! But worry not! This is happening very VERY slowly.
So slowly, in fact, we're only talking a matter of inches over an entire century!!
Why is this happening so slowly, you ask?
Because we're not talking about the actual cement you're standing on right now, we're talking about the subtle shifting of land within the Earths Crust! (Which is the thin fluid-like shell 'floating' on the very dense and very thick Mantle!)
Now here we come to the earthcache logging requirements.

Logging requirements!

Go to the posted coordinates and find the benchmark cemented into the northwest corner of the building. Take an elevation reading. Compare your elevation to what is stamped in the benchmark (from 1934.) Now answer these questions:
1. What is the difference in your CURRENT elevation reading and the one stamped in 1934?!
2. What do you think is happening? And why?
Email us what you find then write up your 'Found It' log! And of course, pictures are always welcome (but not required.)
(We're looking forward to tracking the elevation readings over time!)

Of Note; This benchmark is located on public property, in front of the Federal Courthouse Building, and is accessible from the sidewalk. But anyone with outstanding warrants is advised to skip this earthcache! (Haha! Rotten!) So please, no loitering or otherwise looking suspicious!

Click here to log the Benchmark!

Earthcache.org

Our sources include; This Chicago Tribune Article. This story from the National Oceanic and Atmospheric Administration. And of course This wikipedia page.
Here's a short write-up about the history of the courthouse.
If you need help re-calibrating your altimeter, do what I did and go to aviationweather.gov and find your nearest airport's atmospheric pressure reading!
The Davenport and Moline airports info can be found Here!

Additional Hints (Decrypt)

[Don't forget your Altimeter!] [North side. Corner. 4' up. Can't miss it.] . [Log the benchmark! MG0321]

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)


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