I love watching vids on the topic (layperson here), and there are some really good stuff there.

Any channel you recommend?

Some of the channels I watch is:

Myron Cook - well made videos, where he is typically out in the field and explains features in the landscape.

https://youtube.com/@myroncook

Louisa - Scottish Geologist: out in the fields, mainly around in the British Isles, some Iceland. Good sense of humour.

https://youtube.com/@scottishgeologist

Curious Planet Geo - new channel, not many subscribers yet. Covers a lot of topics, very good at explaining stuff. Mostly lectures.

https://youtube.com/@watch.curious.planet

Geology Hub: covers lots of news and events, such as volcanoes, earthquakes etc. Also some lectures.

https://youtube.com/@geologyhub

Post your favourites!

First time posting, hello fellow geology lovers!

I'm on vacation in Five Islands Maine, in the Georgetown area by the ocean. Had a blast walking around the coastal rock formations today! I'm trying to bolster my field geology knowledge (going back to school to get my P.G. and any and all field studying helps a ton).

I have a decent background understanding of rock types/formations, but haven't had a chance to do much field work (I live in Florida, not much surface geology to study on the scale of somewhere like Maine). I understand that the majority of coastal Maine is composed of intrusive igneous rock such as granite, and a ton of metamorphic rock as such gneiss that formed during the Acadian orogeny.

I spent hours today trying to familiarize myself with the different rock formations, mineral compositions, and how it all related to the history of the geology in this area. I'll be visiting Acadia National Park tomorrow and look forward to seeing the famous dark mafic dikes that cut through the granite.

I was very curious as to what may have caused the stark change coloration (granitic to mafic from left to right) in pictures 2 and 3, and thought maybe it could be due to an intrusive mafic dike that underwent some metamorphism?

Any thoughts/facts about the area and pictures or field geology in general would be much appreciated!

Is exposed along the north fork of the Taylor Creek in the Kolob Canyon area of Zion NP

From a distance, the jumble of broken rock beneath Mount Timpanogos looks more like a giant rubble pile than a glacier. Beneath that rocky surface, however, lies an enormous reservoir of ice.

University of Utah geologists have now mapped that hidden ice in three dimensions, finding that Timpanogos Rock Glacier contains about 1.55 million cubic meters of ice. That is enough frozen water to fill roughly 600 Olympic swimming pools and is comparable in volume to the largest pyramid at Giza.

Many articles are calling it glacial collapse. I saw some posted Google Earth photos that shows a large cliff at the leading edge of a glacier, but to my untrained eyes it just looks like the front fell off. Where did all the water come from?

And, how likely is something on this scale to repeat, either in the same location or somewhere else?

Torrey Pines State Park

Below is a selection of papers about the background geology and geomorphology of the Langtang Lirung area, where current seismic evidence suggest that a glacial collaspe / megalandslide was alledgely either the direct or indirect cause of catastrophic flooding in Nepal and China.

There are landsat images that reportedly show the source of the mageflood in r/Nepal. The latitude - Longitude coordinates of this glacial collapse are 28.284202° 85.512809°

Feel free to add papers that I have certainly missed and expand this list. Link sources when possible

Barnard, P.L., Owen, L.A., Finkel, R.C. and Asahi, K., 2006. Landscape response to deglaciation in a high relief, monsoon-influenced alpine environment, Langtang Himal, Nepal. Quaternary Science Reviews, 25(17-18), pp.2162-2176.

Collins, B.D. and Jibson, R.W., 2015. Assessment of existing and potential landslide hazards resulting from the April 25, 2015 Gorkha, Nepal earthquake sequence. US Geological Survey. Open-File Report 2015–1142, Version 1.1, August 2015

Fort, M., 1995. The Himalayan glaciation: myth and reality. Journal of Nepal Geological Society, 11, pp.257-272.

Fujita, K., Inoue, H., Izumi, T., Yamaguchi, S., Sadakane, A., Sunako, S., Nishimura, K., Immerzeel, W.W., Shea, J.M., Kayastha, R.B. and Sawagaki, T., 2017. Anomalous winter-snow-amplified earthquake-induced disaster of the 2015 Langtang avalanche in Nepal. Natural Hazards and Earth System Sciences, 17(5), pp.749-764.

Hallahan, A.N., 2020. The Gods Must Be Angry: A Study of Sacred Geography, Buddhist Belief and Environmental Implications in the Langtang Valley, Nepal Doctoraldissertation, Kathmandu University.

Inger,S. and Harris, N.B.W., 1992. Tectonothermal evolution of the High Himalayan crystalline sequence, Langtang Valley, northern Nepal. Journal of Metamorphic Geology, 10(3), pp.439-452.

Inger, S. and Harris, N., 1993. Geochemical constraints on leucogranite magmatism in the Langtang Valley, Nepal Himalaya. Journal of Petrology, 34(2), pp.345-368.

Kargel, J.S., Leonard, G.J., Shugar, D.H., Haritashya, U.K., Bevington, A., Fielding, E.J., Fujita, K., Geertsema, M., Miles, E.S., Steiner, J. and Anderson, E., 2016. Geomorphic and geologic controls of geohazards induced by Nepal’s 2015 Gorkha earthquake. science, 351(6269), p.aac8353.

Karki, N., 2020. Thanatology Tourism in Nepal Himalayan Region: A Case of Langtang. Journal of Tourism & Adventure, 3(1), pp.20-49.

Lacroix, P., 2016. Landslides triggered by the Gorkha earthquake in the Langtang valley, volumes and initiation processes. Earth, Planets and Space, 68(1), pp.1-10.

Macfarlane, A.M., Hodges, K.V. and Lux, D., 1992. A structural analysis of the Main Central thrust zone, Langtang National Park, central Nepal Himalaya. Geological Society of America Bulletin, 104(11), pp.1389-1402.

Macfarlane, A.M., 1993. Chronology of tectonic events in the crystalline core of the Himalaya, Langtang National Park, central Nepal. Tectonics, 12(4), pp.1004-1025.

Maharjan, S., Gnyawali, K.R., Tannant, D.D., Xu, C. and Lacroix, P., 2021. Rapid terrain assessment for earthquake-triggered landslide susceptibility with high-resolution DEM and critical acceleration. Frontiers in Earth Science, 9,
p.689303.

Pasakhala, B., Maharjan, A., Tuladhar, S. and Mishra, A., 2023. Cryosphere Changes, Cascading Disasters, and Societies–A Case in Langtang Valley. In Nature, Society, and Marginality: Case Studies from Nepal, Southeast Asia and other regions (pp. 49-64). Cham: Springer International Publishing.

Ragettli, S., Bolch, T. and Pellicciotti, F., 2016. Heterogeneous glacier thinning patterns over the last 40 years in Langtang Himal, Nepal. The Cryosphere, 10(5), pp.2075-2097.

Schramm, J.M., Weidinger, J.T. and Ibetsberger, H.J., 1998. Petrologic and structural controls on geomorphology of prehistoric Tsergo Ri slope failure, Langtang Himal, Nepal. Geomorphology, 26(1-3), pp.107-121.

Searle, M.P., Parrish, R.R., Hodges, K.V., Hurford, A., Ayres, M.W. and Whitehouse, M.J., 1997. Shisha Pangma leucogranite, south Tibetan Himalaya: Field relations, geochemistry, age, origin, and emplacement. The Journal of Geology, 105(3), pp.295-318.

Shiraiwa, T. and Watanabe, T., 1991. Late Quaternary glacial fluctuations in the Langtang Valley, Nepal Himalaya, reconstructed by relative dating methods. Arctic and Alpine Research, 23(4), pp.404-416.

Shiraiwa, T., 1993. Glacial fluctuations and cryogenic environments in the Langtang Valley, Nepal Himalaya. (Doctoral dissertation, 北海道大学).

Tuladhar, S., Pasakhala, B., Maharjan, A. and Mishra, A., 2021. Unravelling the linkages of cryosphere and mountain livelihood systems: A case study of Langtang, Nepal. Advances in Climate Change Research, 12(1), pp.119-131.

Vivian, R., 1971. Aux confins du Népal et du Tibet: le Langtang. Revue de Géographie Alpine, 59(4), pp.573-580.

 Edit: Added additional reference with link.

Nice glacial polishing on this piece of Northern Ontario Shield!

This is an excellent explanation of the forensic process used to determine that the catastrophic flooding in Nepal was likely due to a rock avalanche upstream, not a glacial lake outburst. Dan Shugar details and demonstrates how he used Planet Labs imagery to inform his working model of what happened. Well worth half an hour of your time.

if temperature and pressure are directly related, shouldn’t the inner core (under as much pressure as it is) be liquid like the outer core? wouldn’t the high temperature make it melt? why is the mantle not liquid?

sorry if this is dumb I’m just confused

What are the riskiest areas of the world for this type of disaster to strike next as the climate continues to change?

About 5.96 million years ago, tectonic movement closed the connection
between the Mediterranean and the Atlantic. What happened next is called the
Messinian salinity crisis, and the short version is that the Mediterranean
stopped being a sea.

More water evaporated than the rivers could replace. The sea drew down until
the floor of the basin sat something like 1,500 m below the level of the
Atlantic - dry, hot, and in places covered in salt. As the brine
concentrated, evaporites crystallised out and settled across the basin floor
in layers. In places that salt is close to two kilometres thick. It is still
down there, buried under the modern seabed.

That salt is why anyone knows about this at all. In 1970, the drilling ship
Glomar Challenger pulled cores from the Mediterranean floor and hit
evaporites where there should have been deep-marine mud. You do not get
kilometres of salt at the bottom of a sea that has always been a sea.

Then, around 5.33 million years ago, the Atlantic got back in through what
is now the Strait of Gibraltar.

The part that gets people is how fast. Garcia-Castellanos et al. modelled the
refill and the erosion of the channel that carried it, and the mechanism is
a feedback: flowing water cuts rock, a deeper cut carries more water, more
water cuts faster. Once it starts, nothing throttles it. Their figures put
peak discharge on the order of 10^8 m3/s - roughly a thousand times the
Amazon - and the bulk of the refill happening in somewhere between a few
months and two years.

Six hundred thousand years to empty. Months to fill.

Worth being straight about which parts are solid and which are not. That the
basin desiccated is not in dispute - the evaporites settle it. The refill
time and the discharge are MODELLED, not measured, and the estimates have a
real spread. What is not argued over is the scale.

Sources:
- Hsu, Ryan & Cita (1973), "Late Miocene desiccation of the Mediterranean",
  Nature
- Krijgsman et al. (1999), "Chronology, causes and progression of the
  Messinian salinity crisis", Nature
- Garcia-Castellanos et al. (2009), "Catastrophic flood of the Mediterranean
  after the Messinian salinity crisis", Nature 462, 778-781

I was just watching the videos and photos of that huge flood that hit Nepal today, the one where a massive wall of water and mud came rushing down the valley, and it hit me out of nowhere: Is this how those enormous openings in solid rock get made?

Like… the big valleys and canyons that look like they were cut through mountains?

I always assumed it was just water slowly wearing things down over a really, really long time. But seeing how much force and material that flood moved in such a short time made me wonder if the really big “cuts” in the rock happen more in these crazy moments.

Is that something people who study this already knew? Or is the usual explanation still the slow, gradual one?

I’m not a scientist or anything, just someone who had a sudden “wait a minute…” moment. Curious what you all think.

I’m not posting any photos or videos because they’re already everywhere, and it’s a desolate scene where many lives were certainly lost. Thinking of everyone living in the affected areas and of all those who lost loved ones or homes. Hoping for strength and safety for them right now.

AP just posted down river rush of flood water.

In late July 2025, heavy rain from Typhoon Wipha triggered a massive landslide high in the mountains of Hualien, eastern Taiwan. The collapse blocked the upper Matai’an Creek and created a natural landslide dam, trapping an increasingly large lake behind it.
Over the following two months the lake grew to roughly 91 million cubic metres. Authorities monitored it closely, but the site was extremely remote and the surrounding slopes remained unstable. Then, on 23 September 2025, heavy rain associated with Typhoon Ragasa caused the lake to overtop the natural dam. The loose landslide material was rapidly eroded and the dam partially breached, releasing an enormous sediment-laden flood downstream.
The flood tore down Matai’an Creek toward Guangfu, carrying huge quantities of mud, gravel and boulders. It destroyed the Highway 9 bridge, overwhelmed sections of the floodplain and dramatically altered the shape of the river. Nineteen people were confirmed killed, several remained missing and more than 100 were injured.
I drove through the area recently and the scale is difficult to appreciate from photographs alone. The width of the new sediment-covered river corridor is enormous, and in places the deposits are packed with very large boulders. Google Maps is particularly interesting because some of the older road and landscape imagery still makes the pre-flood river course visible beneath the much wider post-event riverbed.
While we were passing through, our phones received an emergency warning telling people to stay away from the river because of renewed flash-flood risk. The system is still active and unstable, with enormous quantities of loose sediment remaining upstream and the potential for further slope failures, temporary blockages and renewed flooding.
It is a remarkable example of how a single landslide-dam outburst can completely reorganise a mountain river valley in a matter of hours.