I'm not a geologist but I'm genuinely curious about this rock I found on a beach in the north of Jamaica. It's quite soft, chalky, very porous and has little red and green flecks in it. It also has a delicate, papery matter stuck to it which I assume is seaweed remains - but I could be wrong!!

Can anyone tell me how it might have formed, what the red flecks are and what the papery matter is?

Much appreciated!!

Found this cool rock on a construction site in Ohio. My sedimentology is extremely rusty. My guess is this originally from an area in a floodplain near a river or something since it appears to alternate between gray sandstone and brown mudstone.

Normally I don't need any extra help but for some reason I just keep getting stuck on this topic. I understand that SiO_4 is the basic building block for the silicate minerals, but for some reason when I try and think of SiO_4 being inside os SiO_2 it throws my brain off. Why is SiO_2 considered SiO_2 when it has Si_O4 inside of it, because if you took a single compound of SiO_2 it would be SiO_4 meaning for each silicon you have 4 oxygen but the formula says for quartz you should have for each silicon 2 oxygen. I genuinley just want to understand why this is the way it is and why it makes sense, any explanantions or resources on this are greatly appreciated.

In my town we got beautiful curbs of different types. Im assuming gneiss and granite but not sure. My favorite is the first stone, looks like a piece of art.

Some communities declined sharply after one of the largest volcanic eruptions of the Holocene, while others continued growing surprisingly close to the devastation. A reconstruction of prehistoric Japan’s population patterns suggests that catastrophe produced no single outcome.

Conditions before the eruption, access to recovering ecosystems and possible movements of survivors all shaped what followed. The evidence complicates an archaeological debate often framed as either total collapse or straightforward survival.

The international study, reported in Science Advances, examines the Kikai-Akahoya eruption about 7,300 years ago. Enrico Crema of Cambridge University led the analysis, with Lund University archaeologist Peter Jordan as senior author. Their team modeled changes in archaeological radiocarbon dates across Japan. They then compared the reconstructed trends with pottery, tools, settlement evidence and volcanic ash deposits.

I have done my geology research and I live on the boundary of the Eagle Ford Shale and Austin Chalk. The chalk here has layers of Calcite that precipitated out of the other rock forming these layers. I have found out the chalk/shale is of Jurassic age. Also I have a big collection of amorphic Calcite that I have found around my neighborhood.

Note: the lines on the rocks don’t all go in the same direction. Some vertical and other horizontal

Does Freiberg have strong industry connections in mining, mineral exploration and economic geology? Are international graduates finding jobs after completing their Master's?

How good is TUM's MSc in Engineering Geology and Hydrogeology for getting a job in Germany after graduation, especially for international students?

Maybe a different way of phrasing it with different geographical context, why did the Yellowstone hotspot transition from the basalt that made Siletzia and the Columbia River basalts into the rhyolite that made the more recent calderas? Does only 10ish km of continental crust make that much of a difference or was it something else to do? I read that there’s not much intermediate rock like andesite?

Okay these first materials are from our land. As near as I can tell, we are terrace deposit or Tokio formation. I'm southeast of Idabel and our house literally over looks the coastal plain. Forgive me for not posting the exact location. All my clays are sandy. These where processed to remove most of the sand before testing.

This is a light colored clay. It's a pain to access as it's at the bottom of a creek with steep banks. Right next to it is a spring that has never stopped running even during really dry years. In the creek I find lots of quartzite. I've found a few agates and some conglomerates. I found what I think was white serpentine in this light colored clay (white, very sparkly). These pipe (?) structures are upstream from the clay layer. The red is hard sandstone and the white is more of the white clay. The creek also has lots of white sandstone (?). The sandstone contains very little clay but can be broken apart pretty easy. The clay fires above cone 6 (about 1200C)

This next one is the white sand I removed from the light colored clay. There are other locations that contain just the white sand without the clay.

This one is a an extremely fine sand. This comes from an odd low spot on top of a hill that holds water when it's wet. It's got alot of organics in it from the water and the trees so I processes it and pour off what little clay and the coarser sand particles. I get some sandstone and iron concretions out of it. This stuff is powder fine. Makes an awesome glaze ingredient that I don't have to grind.

This is the main local clay that I use. It's in a higher layer than the light colored clay. This particular batch of clay, I removed all the sand and it fired with less than 1% absorption at cone 6. Sounds perfect until you realize it has a 15% drying shrinkage. So I leave most of the fine sand and mix it with feldspar and kaolin. It's acidic and their does seem to be significant differences in firing temperatures depending on where I dig it, but how much sand I remove affects that as well.

I call this one Sugar Creek clay but I think it maybe Walnut clay? Found under layer of what I believe to be Goodland limestone. Location is 33.92747055603416, -94.53065741860809. Plastic vitrified at cone 02. It had pieces of limestone in it and I sieved it down to 100 microns. I use it as a glaze ingredient now. I think I roasted this at 1000F before the analysis but don't remember for sure.

This material is from a local limestone quarry above the limestone and hard pan layers. I believe it to be Kiamichi Shale. Location 33.93060978243283, -94.77100598594791. It looks like shale and at first wouldn't break down in water but I dried it in my oven and then it broke down and was plastic enough to form test bars. I also use limestone from this quarry as a substitute for whiting.

And last but not least, this is a marl from Southwest Arkansas. Location is 33.680160646301445, -94.44293602420451. I was hoping it was chalk when I dug it but it was actually plastic enough you could roll a coil and wrap it around your finger. If you check the location on google maps, you can see the cement plant just down the road and where they mine the marl/chalk for cement.

This glaze is 49.5% local materials.

Hey yall. I am wondering if anyone has any monocle or eyeglasses magnification lens recs for field work. Due to eye problems, my eyes have a hard time refocusing after using a hand-lens and would like to reduce the stress on my eyes when refocusing. I understand that hand-lens are sturdy and great for fieldwork however I would like something that I could use both eyes for mineral identification. I have been trying to look at different things like jewelers glasses but have not found anything that would do what I am looking for.

Hand-lens that are glasses friendly are also welcome as well.

I'm a potter who enjoys working with local materials and have made some effort to identify formations. I've had whole rock analysis done on quite a few local materials. If anyone is interested I can share those with the geology information I have.

EDIT: I made a post with the analysis and pictures https://www.reddit.com/r/geology/comments/1x60nnt/chemical_whole_rock_analysis_of_some_materials/

Found a rock with a slight crack, broke it and found this :)

I put together a 12-minute reconstruction of Sunday's flash flood on the Budhi Gandaki in Gorkha, Nepal. It's the second major Himalayan flood in seven weeks, by ICIMOD's count. What it covers:

- The gauge record: at Arughat (DHM station 3572) the river rose about 5 m in 30 minutes, with no rainfall, before the gauge went silent at 08:40.

- The seismic signal: a 4:22 am signal on the KKN station, flagged by Kristen Cook on the day.

- The source area: the Syar Khola below Chamar, compared in Sentinel-2 images from 1, 6 and 11 Oct.

- Precedent: Rasuwa, Birendra Tal (2024) and Chamoli (2021, Shugar et al., Science).

- The official finding, which landed after the film was made. NDRRMA's preliminary assessment says an ice-rock avalanche at about 4:20 am triggered a landslide whose debris repeatedly blocked the Syar Khola, backing water up about 1.5 km. ICIMOD says satellites confirm an ice-rock avalanche and glacier collapse. The film calls the cause unconfirmed, so read those sections with that in mind; the update is in the description.

I deliberately didn't model a dam height, lake volume or breach hydrograph, because no agency has published one. The flood front and the dam cutaway are illustrative; the terrain (Copernicus GLO-30) and the gauge levels are real.

A question for people who know Himalayan mass flows: with repeated blockage and partial breaches rather than one dam failure, would you expect a single 5 m pulse like the Arughat trace, or several smaller ones that merge downstream?

https://www.youtube.com/watch?v=gVxF-vGrw1g

I was looking for one for Maine so I could see why types of rocks were along particular coastal areas. It seems everything has been pushed into the National Map format, and I have to download individual maps. This is frustrating when I want to view an area as a whole.

Source of the pictures here and here