rocks from my pockets

this is just a place for me to get weird about geology and let my magpie brain run free sometimes | she/her | late 20s | grad student in completely unrelated field

[rocksfrommypockets]

Lots of quartz fun from a ramble across the Pit Formation off Shasta Lake reservoir, far Northern California

[eutrochiumfistulosum]

Favorite slab of limestone among Indiana University's fieldstone walls. This is on the south side of 10th Street, along the arboretum, across from the business school. I'm always awed by it when I walk by.

[sketches-and-such]

Field Museum specimens for the reconstructive fossil invertebrate project compiled into one plate. (Individual illustrations visible on my website.)

[gottalottarocks]

Since so many of y'all who are new here don't have icons

Here are some I made for you that you can use for free and without credit

If you like or use them, they’re all on my redbubble page if you want to check it out

[radstarsaur]

A gaggle of Ammonoids. Can you name them all?

[portalithics]

Okay, uh Danny, Ben, Alan, Brad, Sally, Daveth, Sally 2, Brian, Ryan, Grussel, Paul, Mavis, Esther, Justin, Pilaf, Frank, Usul, Ellen, Bellen, Alice, Trince, Hellen, Third Sally, Drendel, Biggo, Torichan, Phyllis, Brandon, Cranston, Lisa, Chanter, Frikk, Santa, Warp, Alexander, Shelly, Monty, Arnold V, Seven, Evan, Porridge, Helga, Princifer, Sherik, Dondo, Deedee, Ashley, Erica, Lawrence, Klezmer, Paper, Spike, Station, Piano, YHWH, Amerigo, Abendigo, Justine, Cristal, Krystal, Jonathan Brandis, Grandis, Socrates, Denise-Fromage, Donald Fagan, Second Cranston, Phoebe, Rachel, Ross, Chadler, Joey, Courtney, and Literally Satan

Did I name them all??

[rocksfrommypockets]

Brachiopod fossils in the Kaibab Limestone

Grand Canyon, Arizona, USA

[rocksfrommypockets]

Smoky quartz, central NC, USA

[peachdoxie]

I ended up on the Wikipedia page for "oldest dated rocks" and it's got me feeling all sorts of fucked up about the sheer size of geologic timescales.

[peachdoxie]

Rocks from the Hadean eon — the time when Earth was first forming — are extremely rare because the majority of them have been eroded or melted, or perhaps deep in the Earth, but there are some examples:

The oldest estimated Earth rock is a zircon sample with an age of 4.404 ±0.008 billion years. A few things stand out about that. First, the age of the Earth is estimated to be about 4.54 ± 0.05 billion years old. That's less than 100 million years between Earth's genesis and the creation of that zircon sample. Second, the margin of error on the age of the zircon is 8 million years. That zircon is so old that that's the most precise guess at its age.

The Earth has changed so much, geologically speaking, that a contender for the oldest known rock made on Earth was actually found on the Moon. Lunar Sample 14321, aka Big Bertha, was collected during the Apollo 14 mission in 1971. In 2019 it was estimated at over 4 billion years old. This is a meteorite from Earth, back when our planet was still forming and was being impacted by massive asteroids. There may even be others older than Big Bertha on the Moon, possibly making it the best place to learn about the Hadean eon.

But you know what has me really fucked up? The oldest known rock on Earth isn't actually from Earth. The Murchison meteorite fell in Australia in 1969. Parts of it are estimated to be about 7 billion years old. Again, the age of the Earth is roughly 4.54 billion years old, meaning that this meteorite is 2.5 billion years older than Earth — older than the Solar System and the Sun, even. Our Solar System was just a large cloud of space dust when this meteorite was formed. It's that old.

These rocks were formed on timescales so far beyond our comprehension that I feel insane just thinking about them.

[peachdoxie]

I would LOVE to hear more about finding these hella old zircons.