#paleokarst

[bettergeology]

Paleo-caves in Death Valley

You have probably heard of "caves", or a natural void formed in rock. Caves are formed in a number of ways, but the most familiar are probably those formed in limestone - called karst or karstic. Karst caves are formed by the steady dissolving of limestone rock by naturally acidic groundwater percolating through the ground, often along faults or other natural weak areas.

Death Valley in California is not a hotbed of limestone caves, though evidence of them can be seen in a number of places! Ancient caves, often tens or hundreds of millions of years old, sometimes collapse or fill in with silt/minerals/debris. An ancient cave formation is called "paleokarst", and there are a few areas in Death Valley where you can find it. The easiest to access is in Titus Canyon, a major canyon who's lowest reach carves its way through limestone bedrock, leaving behind towering polished rock walls and revealing the internal structure of the rock.

Titus Canyon's narrow section is carved through the Bonanza King Formation, a Cambrian-age (538 - 485 million years ago) marine sedimentary rock package several kilometers thick. It's found in many areas of Death Valley and the surrounding region. Across its area and thickness, it alternates from dolomite to limestone (dolomite minerals versus calcite minerals). Dolomite doesn't usually dissolve and form caves, but limestone does - and the many fractures in this rock appear to have allowed numerous tiny caves to form somewhere in the distant past. Most of these have since been filled in with calcite minerals, making them paleokarst.

In this image, you can see the void of the cave lined with thinly-layered calcite. It has a flat floor, and these features are characteristic of having formed in a cave. In Titus Canyon, we can find these from a few inches to a few meters across, and as the canyon has been carved into the rock, these voids are exposed. This one below tells an exceptionally clear story:

You don't need to be a geologist to see how this differs from the first example. There's a weird pendant-shaped protrusion hanging from the top, there are layers in the minerals, the bottom half is red… there's a lot going on. Let's get some lines on there and figure out what we can see:

That's better. OK - I've separated out the parts of this outcrop which from my desk look to be distinct. Here's a close-up of part of the left-center area to show how it appears different up close.

OK, so we have the blue-gray limestone bedrock on the right, top, and lower left, then a gray-red area with layers and what looks like gravel or other angular pieces of the limestone. Above that is a finely-layered calcite deposit (remember? that's cave-like!), and above that is a layer of calcite which is rather porous. The top surface of this area is sort of scalloped and curved, which is also characteristic of limestone caves.

Here's the fully interpreted version. Let's go through the sequence of events. First, we have the limestone bedrock of the Bonanza King Formation (BKL). At some time in the distant past, a portion of it dissolved away and formed a cave. Over time, silt and debris filled in the bottom of this cave. Because it is ancient, we call it paleo-fill (OPF). This might have happened at a time when the cave was dry (not containing water), since if it was wet we would expect some amount of calcite to be deposited around its perimeter as is typical in limestone caves.

Above that is a layer of thinly-layered calcite, the cave mineral. This layer contains some reddish silt and the occasional fragment of the limestone, so the cave was probably happily active during the time that was deposited! This is the oldest cave mineralization phase I can discern in this outcrop, so I call it Old Cave Calcite (OCC).

Next, we have a slightly porous, light-colored calcite deposit. The porosity suggests to me that it was deposited faster, but I am not an expert on cave deposits so will not comment further. This unit fills the cave to its top in most places! I call this the Middle-age cave calcite (MAC).

Finally, the youngest unit is another cave-deposited calcite (YCC). As in the first cave picture above, it is a coarser-grained pale yellow color with layers that parallel the sides of the void. Most of the paleo-caves you can find in Titus Canyon are filled with this sort of calcite, and it may be geologically recent (last million years?). It filled the final remnant of this ancient paleo-cave, and is contrasting with the material around it. This visual and textural contrast is what inspired me to write this post in the first place - the best example I've seen in person of paleo-karst and the evolution of a miniature cave system, right in the heart of Death Valley - my favorite place in the world.

[no1frogfan]

For love of the game

Takigawa Chris Yuu x gn reader

Word count: ~800

Tags & warnings: very vaguely suggestive language? (there are some good names in baseball), baseball lmao

Note: Been feeling unmotivated to write, so I decided to tap into my love of Chris and of irl baseball to do some dialogue practice. Thank u to the daiya server for motivating me and to @paleokarst for talking over the ending :*

“What’s that?” You give Chris a quizzical look as he steps through the front door carrying a large plastic storage box in his arms.

“Hello to you too.”

You pad over to give him the usual greeting kiss. “Yeah, yeah, welcome home or whatever. Now tell me what this is.”

“My parents found it while cleaning out their basement and I thought you might want to look through it together.” He sets it down in front of the couch. Reaching inside, he pulls out one of many smaller cardboard boxes and opens it to reveal a neatly-packed row of cards. “They’re my old baseball cards.”

“Seriously?” The box is in your hands in an instant and you immediately begin rifling through its contents.

There's a few minutes of focused silence until, “OH MY GOD,” you exclaim, brandishing a card at him. “This can’t be his real name. Dick Pole?! Dick. Pole.”

“Sadly, it is,” Chris chuckles before holding out a card of his own. “Here, I found one for you.”

“NO. His name is not Rusty Kuntz?!”

He snorts. “Actually, it’s pronounced KOON-tz.”

You erupt in cackles. “I mean…if my name were Rusty Kuntz, I would also insist that it’s pronounced KOON-tz.”

“What else do we have here— hello, what’s this?”

Glancing over, he sees you reach for a small leather binder. “Oh that’s where I kept my special cards.”

“Your special cards?” You tease, “god little Chris was such a little nerd.”

He rolls his eyes, pulling you closer to give you a peck on the head. “Well you’re the one dating me so what’s that say about you?”

“That apparently I like nerds,” and pointing to one of the cards, you urge, “now come on nerd, tell me what’s so special about this guy.”

“Ah, that’s Bob Gibson. He’s a Hall of Famer, probably the best right-handed pitcher in St. Louis history. He was good at fielding too, which is rare for a pitcher. He worked hard and led the team to two World Series wins.”

You flip through a few more pages. “Wow you have a lot of this Iván Rodríguez guy too.”

“Well, he was my favorite player growing up and maybe the best catcher of all time.”

“What makes him the best?”

“He’s a solid hitter and his defensive play is exceptional. He’s got unparalleled game sense and a great strategic mind. Um, he’s caught for some of the best pitchers of the era and he caught nine no-hitters. The only way you can have a no-hitter is if the battery works perfectly, so that means he was able to bring out the best in a lot of different pitchers. Plus, he was always fun to watch.”

“Is he why you became a catcher?”

“You know…” Chris contemplates for a moment, “that’s honestly never occurred to me. My dad was obviously the reason I started, but I played a lot of different positions before deciding on catcher. Dad was the one who suggested I try it — he thought I had a good understanding of the game — but you might be right, maybe I stuck with it because I wanted to be like Iván.”

You hum in response. “Makes sense. The way you described him…he clearly has a lot of qualities that you value as a player.”

It’s long past dinner time when the two of you finally tire of strolling down memory lane and begin to tidy up the mess of cards now littered across the couch cushions and coffee table.

“What are you gonna do with all of these?”

“Well right now I’m going to put them away. Then I’ll probably give some away and throw away the rest.”

“You’re not keeping any?”

“Nah. It’s not like they’re worth anything.”

“Well in that case, I’m gonna keep these.” You swipe the leather binder from the box before he carries the rest off into the storage closet down the hall.

“What do you think?” You gesture toward the refrigerator when Chris returns.

Some of the precious real estate on the fridge door has been tidied up, and a cleaned-up Rangers magnet now holds his signed Iván Rodríguez card front and center, nestled between memories. To its left is a picture of him with his parents and Coach Kataoka after his first game with Seidou. Below it is another picture of him and the coach, this time graduating from Seidou alongside the rest of his teammates. To its right is a picture of the two of you at his MLB debut game, your smile toothy and gleeful as you hold up the ball from his first major league hit.

A lump forms in his throat.

It’s just a baseball card, one fleeting snapshot in the collage of moments that make him, the values that shape him, and the people that support him.

It's just a baseball card, but he can barely get the words out. “It’s perfect.”

[no1frogfan]

Idk what some of these categories are, but this was fun!

Maybe this is just prevalent in a small corner of the fandom, but I also see a lot of divorce & rich boy aus across my dash, and I wonder what y'all think of those! (Personally, divorce is a B for me, and rich boy au is a D.)

No pressure, but I'm also suuuuuuper curious >> @mangoisms @paleokarst @vs-redemption and anyone else who wants to join!

fanfic trope tierlist incoming!!

link to make your own: here

i'll explain any of them in the comments if asked (;

p.s. you can customize the number of tiers and what you name them if you want to elaborate more on some!

tagging (no pressure): @heroesfan101 @kailali @meggsngrits @fushigurro @saintokkotsu-main @true-deru @auslanderka @baka-tsuki @ceenthesis @everything-always @giogama08 @prettyiwa

+ anyone else who wants to do it - would love to see your responses and i know i forgot a few!

[mybeingthere]

The Crystal Mountain (28° 26' E and 27° 39' N) is between the oasis Bahariya and Farafra, northern of the White Desert, Egypt.

The Crystals are probably Barite (Schwerspat, BaSO4) and/or Calcite crystals (CaCO3). The hill was discovered by accident during works on the road from Farafra to Bahariya and has been partly destroyed.

The hill is not a paleokarst cave with columnar-shaped stalagmites. It is a subvolcanic vault, which was probably formed during the Oligocene age. The visible layers are e.g. White Desert limestone of the Khoman Fm.* (Late Cretaceous age), as well as a younger coal seam and hydrothermal impregnated reddish to brownish ferruginous layers.

  https://www.geologyin.com/.../08/crystal-mountain-egypt.html

[khaosb]

#Samula #Cenote #BlueHole #Dzonoot #Paleokarst #Yucatan #Peninsula (en Cenote Samula)

[jorgemomo]

Cenote (del maya dzonoot: ‘hoyo con agua’) es una dolina inundada de origen kárstico. Existen varios tipos de cenotes: a cielo abierto, semiabiertos y subterráneos o en gruta. Esta clasificación está directamente relacionada con la edad del cenote, siendo los cenotes maduros aquellos que se encuentran completamente abiertos y los más jóvenes los que todavía conservan su cúpula intacta. Como otras muchas estructuras geomorfológicas, los cenotes son estructuras transitorias, que finalmente pueden terminar rellenos y desecados, pasando a formar parte de lo que se conoce como un paleokarst