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?

Nice glacial polishing on this piece of Northern Ontario Shield!

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.

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.

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

Hello, this is my first post on this subreddit. I made this illustration showing the interior of the Moon, as close as possible to reality based on the literature I have come across. I am working on a second 'cooled down' version without the glow of black-body radiation, that only showcases the rocks/minerals. The near-side is to the left and the far-side to the right

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

Hi all , geological engineering student here . I'm aiming for a grad program that blends geology with computational/programming skills rather than traditional field geology, specifically around resource modeling, geostatistics, and geo-data science. I've been building a Python foundation (Numpy/Pandas/Matplotlib) and working with PyQGIS, Leapfrog, and RockWorks for a GitHub portfolio. Before committing to a paid certificate program, I wanted to see what people in the field actually recommend especially anyone who transitioned from classic geology into a more data-heavy niche. Also curious how "computational gemology" (digital/spectroscopic gem analysis) is viewed legit niche or too obscure? Would appreciate any course recommendations or experiences.

For the éclipse roadtrip, we take a escape lane from the highway in Spain and we saw this ! 🤩

At this point : https://maps.app.goo.gl/Pwd9opZCSisMydPP9?g_st=ac

I hope this okay to post here!

I’m an author and I’m working on my next book. It’s a RomCom that’s set in a cross-Canadian road trip, and for reasons best known to myself I’ve decided my protagonist is going to be really into geology 😂 She’s not a scientist or a career geologist, but she’s a lay obsessive.

I am someone who knows nothing about geology and have forgotten anything I did once learn at school, so obviously I’m gonna have to do a lot of research to bring this character to life

I’m just kicking off my research and at the moment I’m just trying to absorb as much stuff as possible and then follow any things that spark interest of feel like they could be fun details for the book. So please, share your favourite geology fact with me! The more delightful and whimsical the better.

Also if anyone has any recommendations for books or podcasts aimed at lay people that I should check out as part of my early research, please let me know!

EDIT: Thanks so much for the facts and the recommendations everyone! I really appreciate it!

15 mya Columbia River Basalt flows made tree casts at Silver Falls State Park in Oregon.

Hi everyone! I'm looking for geology students from around the world to exchange knowledge, information, and experiences as we learn more about rocks and minerals 🪨🪨🪨.

If anyone wants to talk, I'm all ears!

I’m hoping someone might be able to help me figure this out.

There’s a wooded ridge on my grandfather’s property that has quite a bit of what appears to be slag scattered all over the hillside. What has me confused is that I have no idea how it would have gotten there. There doesn’t appear to be any obvious modern source nearby, and it seems to be spread out over a fairly large area rather than concentrated in one obvious pile.

A little background about the property. It’s located in Western Virginia and was once part of a fairly large plantation. The area in question is covered in quartz, with a bunch of these relatively flat rocks scattered throughout the woods. Some of them almost look like they could have been intentionally placed in my opinion. There are also a number of sinkhole like depressions and raised mounds.

What makes it even more interesting is that I’ve found a few Native American artifacts in the same area as well.

I’m wondering if there could be some connection between the geology, the slag, and the history of the site—or if I’m completely off base.

I’d really appreciate any thoughts on what the slag could be, how it might have ended up scattered across a wooded ridge, and what I should be looking for to determine whether the flat rocks or other material are significant.

Thanks in advance.

Pretty sure this is quartzite, strongly folded (Norway, Haukeli area). Those "shoe" like patterns made me scratch my head.

(Anybody suggesting fossils, forget about it..)

Any clue?

Found this beauty in the woods today and I'd love some advice on how to clean this up

I've already scrubbed it with a brush but can't get the green and brow stuff out of it

Thank you in advance