misu4sh

[misu4sh]

my friend told me that her boyfriend got her a super cool rock while they were on vacation together and you would not BELIEVE my disappointment when i realized she was talking about her engagement ring

[misu4sh]

MORRISON BASIN GEOGRAPHY

Today for Monday Musings I would like to discuss the paleogeography of the Morrison Basin. There are a few things I want you to learn from this:

-How do we know what it looked like in the Late Jurassic Morrison Basin?

-How do we know it was a basin?

-There were different environments/ecosystems within this very large basin.

Okay, so first. How do we know it was a basin? Easy, the rock record only records deposition (or lack thereof). Deposition happens in areas of low relief: basins. We can extrapolate where the highlands were from fluvial deposits and where we find them (i.e. where the conglomerates vs. the sandstones vs. the mudstones are in the system). As we move downriver from the source rock, the grains in the rocks get finer. Therefore, shales are found in places where movement is minimal such as a lake bottom or ocean floor and conglomerates are found closer to the source rock where fast flowing water could still move the larger grains. Here's a very simplified sketch of this concept:

How do we know what the land looked like? Well, we can find our answers in the rocks. In Canada, the Morrison is not used but there are equivalent rock layers: The Fernie Formation, the Morrissey Formation and the lower part of the Mist Mountain Formation. The Fernie Formation is primarily shales with a few sandstones, cherts, and limestones.

These rocks tell us that this is where the Sundance Sea was during the last part of the Jurassic Period. The Morrissey Formation is made of conglomeratic sandstones primarily with rare beds of mudstone, siltstone and even coal. This indicates a deltaic, nearshore (littoral), beach environment. This formation shows forested rivers emptying into the Sundance Sea.

The Mist Mountain Formation is actually Late Jurassic-Early Cretaceous deposit. It is primarily shale, siltstone, sandstone, and mudstone. This formation represents fluvial channels, floodplains, deltaic, coastal plains and swamps along the Western Interior Seaway as it began to transgress back across the continent.

As we move south into Montana and Wyoming, we can see the environment start to change a little. The base of the Morrison here is the Windy Hill Member, a limey fossiliferous sandstone indicating warm, shallow seabed not unlike the Gulf of Mexico today. This is the extent of the Sundance Sea in the late Jurassic. By this point in time, the sea was regressing off the continent heading towards northwestern Canada and the ocean.

You can even see the white beach sand in the rock and the modern Gulf of Mexico! Neat! Following the Windy Hill in western Montana is the Swift Formation. This is also a marine deposit of primarily orangish brown, glauconitic sandstone. Commonly, it is filled with fossils. It is also shallow marine and some coastal deposits.

Next is the Morrison Formation proper. Like down south in the more famous outcrops, the Morrison in Montana consists of variegated mudstones and sandstones with minor limestones indicating fluvial and lacustrine deposits.

The biggest difference is that there is no clay change like on the Colorado Plateau (it doesn't become smectitic). This tells us there was no volcanic activity up north.

As we move south through Wyoming, the Morrison continues to have the typical variegated mudstone and sandstone profile, however, it has recently been noted to be mostly lacustrine (lake) deposits rather than fluvial (river). The basal Morrison in Wyoming is the Windy Hill Member (the regressive marine sequence). Perhaps the lakes were what was left after the sea retreated.

Northern Utah and Colorado are very similar to Wyoming with slightly more fluvial rocks than lacustrine, such as at Evil Tree Bonebed (I know, shameless plug but our site is so COOL). Things also start to show the clay change from illitic to smectitic showing that volcanism is becoming prevalent.

As we continue heading south through Colorado and Utah, more members are separated out and we see the seaonsal wet/dry cycles appear in the rock record. The Morrison down here is primarily fluvial sandstones and conglomerates and the variegated, smectitic mudstones.

(Grand Junction Morrison Formation)

As we continue south onto the Four Corners area, we become even more arid. In fact, there was a large saline lake there not unlike the Great Salt Lake in northern Utah now. It was called Lake Too'dichi and geochemistry tells us it was very saline and contained a lot of smectitic minerals that have aided in uranium ore development in the area.

(the Great Salt Lake from my plane home from GSA)

Lastly, in South Dakota and in the Colorado Plateau we find sand dune deposits ( Bluff and Unkpapa Sandstones) indicating small deserts forming.

So, when we put it all together, we make a paleomap that looks something like this:

Neat, right? You can see the retreating sea and the large river systems and the arid areas. I personally would put Lake Too'dichi on there too as it's like Great Salt Lake size but this is good enough for our purposes.

I hope you were able to learn something new and exciting about how rocks tell us about paleoenvironment and I will fossilize y'all later!

[misu4sh]

Why the fuck would you taste it?!

[misu4sh]

Undulatus Asperitas clouds seen over New Hampshire (2023)

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Comet Leonard

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A few tarot readings open

Hey guys! I haven't done this in a while but I'm opening a few free tarot readings. Please reach me through my dms with your desired question and your initials + the initials of any other parties if applicable.

To recieve a reading, please repost this post and follow me. I'm doing free readings in exchange for some reach!

[misu4sh]

Green Rainbow Natural Iridescent Pyrite From Peru

[misu4sh]

depending how much sodium, potassium, and/or calcium is available, you can get different feldspars! labradorite is my favorite.

remember: stay OUT of the miscibility gap.

there are NO FELDSPARS in the gap. you can't fit that much calcium and potassium in one feldspar. it's not done.

[misu4sh]

NEAT ASTERISM

Black Star Diopside

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this guy's beef got old enough to have geology

[misu4sh]

Free Tarot Readings! Very Nutritious!

Any time is a good time for some Tarot Snacks! If you’re looking for a free tarot reading, I can do it for you! And yes, it really is free! Just send me an ASK describing your current situation and what you want to know about it and I’ll do a reading for you. Don’t forget to leave your name or initials!

RULES

1- Be kind! The cards might indicate something that you don’t like and it’s not my fault. I’m here to help you and I’m doing it for free. The only payment that I require is to be treated kindly.

2- Before you send me an ask, like this post and if you feel like reblogging it, do it, although not required.

3- You need to share something about you with me. You can tell me something positive that’s been going on with your life or you can even share with me things like your favourite colour, music that you’ve been listening to nonstop… Anything positive you feel like sharing with me. 

Much love,

Vini. 💜

[misu4sh]

Is Dwayne Johnson Igneous, Sedimentary, or Metamorphic?

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important psa

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Cretaceous Characters - Quetzalcoatlus meets a sub-adult triceratops. Just a silly paleoart cartoon thing of mine.

[misu4sh]

Free One Card Pull — Tarot Game.

I will be offering one card pulls through my ask box, but please read through this entire blog before you request one!

Information.

I will be pulling one card for you! The reading will be a message from The Universe, but if you would like — you can ask one question. The interpretation will be around one single paragraph since I'm doing these for amusements sake. I will likely get to everyone!

Rules.

No anonymous requests.

You agree to wait patiently. I have a life outside of this Tumblr account, so I might take some time.

In the request, include your initials and pronouns.

Follow me.

Like and re-blog this post.

Write in the comment section if it resonated or not. If you don't do this within a week, there is a chance I might not give you a reading again in the future.

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[misu4sh]

writing be like

[misu4sh]

Free pendulum ( 5 questions only) and tarot readings are open per person.

Rules:

Follow me

Like and reblog this post.