Slickensided kettlebottoms

are a coal mine hazard. Coal mining is more complicated than it looks. Floors can heave too, though this is slower than having the cast of a carboniferous tree fall on you.

I love the word slickensided, and can't remember where I heard of it before. I didn't know what it meant then.

Kilauea caldera collapse

A time-lapse from the USGS:

Spinning cores

You probably saw the report that the Earth's inner core changed rotation direction. Color me dubious.

I'm not dubious because there's too much rotational energy involved: it is next to the outer core, which is "liquid" and has its own rotations and vortices, which could conceivably push the inner core one way or another. That has a lot more angular momentum and is, if a cursory read is any guide, fiendishly complicated.

(And the moon apparently makes the inner core's rotation precess--the axis of revolution changes.)

In fact, some calculations suggest that chemical plumes can play a major role in convection--not just thermal ones. The chemical changes come when iron crystallizes out on the inner core, releasing oxygen which gets taken up in other, lighter compounds which (the link suggests) can burst out of the interaction zone when enough accumulate. We don't know the chemistry, or the "burping rate" well at all.

In order to "see" the core, your sound waves have to traverse the crust (easy), the mantle (we sort of understand), and the outer core--and its dynamics are actively debated. Can things change on the time-scale of decades? Unfortunately, papers don't always give the units in forms familiar to me (that one is on convection in the inner core! and Figure 13 shows convection times on the order of at least 10 million years).

One estimate has large-scale flow at the top of the core at about 10km/year. If that's the same at the bottom and all in the same direction (!), and with good coupling to the inner core, it would seem to suggest a "flipping" time of order a few hundred years.

I spent more time than I expected in this really deep rabbit hole, and came up strongly suspecting that the measurement the team made has gigantic error bars, and that the story got publicity for its novelty value.

I don't know how long this visualization of turbulence in the outer core will be up. It's a simulation, of course, salt to taste.

Chicxulub again

The Deccan Traps eruptions were roughly contemporary with the Chicxulub event; enough that there has been a lot of argument about which caused the extinctions, and I'd wondered about whether the latter could have triggered the former, as the shock waves refocused on the other side of the planet. It seems not, though the shocks seem to have triggered extra eruptions along the way.

The latest tsunami model displays, among other things, the estimated position of India at the time. The latitudes match (20N vs 20S), but their best estimate for the longitudes doesn't have India and Chicxulub on opposite sides, by about 60 degrees. A little more evidence against my theory.

The Old Ones. Or not.

The Scientific American has an article about long-lived microbes inside the Earth. Tuning the metabolism down to nearly nothing, a surprising quantity of living things can survive where you wouldn't expect there to be enough food. Nothing big, mind you--just microbes.

One bit that surprised me was about Lipman

Back in the late 1920s, a scientist named Charles Lipman, a professor at the University of California, Berkeley, began to suspect there were bacteria in rocks. Not fossil bacteria. Alive bacteria.

When placed in solutions of coal dust and sterile water, in two to three weeks he began to see what looked like bacteria.

...

Intriguingly, he found that a rehydration period of at least a few days in liquid was essential for revivification. If the crushed coal was wetted but immediately placed on food-infused gelatin-like agar in a Petri dish, nothing grew.

...

In fact, he found that heating the sample for hours at 160°C never managed to kill the bacteria inside the coal. If anything, it only seemed to encourage them. The longer they were baked – up to an incredible 50 hours – the better they seemed to grow when the coal was subsequently crushed (If his results were genuine, they may not be altogether surprising given both the conditions that create coal and the effects of heat shock proteins).

That's a pretty dramatic result, and I'd expect lots of people would check it out. But a quick googling doesn't show that anybody has reproduced his results. On the contrary:

S.K. Roy, 1937 Popular Astronomy 45:499.

Charles Lipman claimed to have found living bacteria in stony meteorites. Roy doubts this, pointing out Lipman had also "found" living bacteria in ancient terrestrial rocks and coal, but that other scientists had failed to verify this. Roy also tried to obtain living cultures from meteorites, but failed.

Did the experiments that "failed to verify this" ever get published? If not, why not? Popular Astronomy vol45 doesn't seem to be available online. I will have to see if the Astronomy library has a copy. Maybe it will have references.

The failure to reproduce ought to be as famous as the claim.

Just a reminder

Earthquakes and undersea landslides can happen in the Gulf of Mexico too.. A map is here.

There are other hazards associated with the Gulf:

Submarine volcanoes have the ability to emit large amounts of gas into their surrounding waters. These gas emissions can happen suddenly, at any time, and are not always tied to a volcanic eruption.

If the amount of gas is large enough, it can significantly reduce the density of the water. Ships on the surface will ride lower in these waters or even sink quickly when the gas-laden waters are encountered. This hazard is one of the reasons why ships are advised to steer clear of the area around Kick ‘em Jenny when any activity is detected. Volcanic gases can also be deadly.

Kick ‘em Jenny is an unusual name for a volcano, and many people are curious about its origin. The name was once used for Diamond Island, which is a short distance away from the volcano. That name was given to the island and its surrounding ocean because the waters there can be extremely rough. After the volcano’s first known eruption in 1939, people began referring to it as “Kick ‘em Jenny” and the name stuck.

My wife's father told us of having to monitor water temperature carefully when his sub was near a Pacific volcano--if they got into hot water they could have trouble controlling their depth.

Moving mud pit

A mud pit is on the move.. "first 60 feet over a few months, and then 60 feet in a single day"

Yes, it is in the San Andreas fault area, and yes it is warm water that smells of rotten eggs.

"Union Pacific has been forced to build temporary tracks to avoid running trains over land impacted by the spring. Trains are now moving more slowly through the area, according to the company."

For some strange reason I'm reminded of this story we used to read to the younger kids.

Mazon

On the way back from Louisville we detoured and spent about an hour and a half fossil-hunting in the Mazon Creek park. There were once coal strip mines, and the tailings include some very well-preserved soft-bodied fossils. The loop we walked was very much overgrown and covered with long dry grass and medium height green grass, alive with ticks. (We disposed of at least 60 on the first leg of the trip--very few on the rest.) Here and there one could find a few promising rocks, but the bulk of those I picked up were by the road.

You can sometimes crack a rock open with a hammer, but that's not reliable and can crack it in the wrong plane to view anything. The approved approach is to soak them in water and then freeze them--perhaps repeatedly. We'll see. I picked up quite a few opened and discarded rocks by the roadside--some of which look rather jelly-fishy. Somebody was impatient.

The strip mines are now oddly shaped lakes, with hills in between.

Old stories

Ngimun, Yidyam, and Barany are crater lakes in Australia. There's a story of how they came to be:

It is said that two newly-initiated men broke a taboo and angered the rainbow serpent Yamany, major spirit of the area ... As a result 'the camping-place began to change, the earth under the camp roaring like thunder. The wind started to blow down, as if a cyclone were coming. The camping-place began to twist and crack. While this was happening there was in the sky a red cloud, of a hue never seen before. The people tried to run from side to side but were swallowed by a crack which opened in the ground'....
.. After telling the myth, in 1964, the storyteller remarked that when this happened the country round the lakes was 'not jungle - just open scrub'. In 1968, a dated pollen diagram from the organic sediments of Lake Euramoo [Ngimun] by Peter Kershaw (1970) showed, rather surprisingly, that the rain forest in that area is only about 7,600 years old.

Some other stories refer to places that haven't been above water in 9000 years. "The stories tell of a river that entered the sea at what is now Fitzroy Island. The great gulf between today’s shoreline and the reef suggests that the stories tell of a time when seas were more than 200 feet lower than they are today, placing the story’s roots at as many as 12,600 years ago."

"In one of their stories, Ngurunderi chased his wives until they sought refuge by fleeing to Kangaroo Island—which they could do mostly by foot. Ngurunderi angrily rose the seas, turning the women into rocks that now jut out of the water between the island and the mainland. ... a time when seas were about 100 feet lower than they are today, which would date the story at 9,800 to 10,650 years ago."

The Aborigines apparently have some careful crosschecks to make sure stories don't change: some stories are sacred and must not be adapted by the storyteller. Some of these stories match the ancient landscape nicely--the settings match.

What doesn't quite match is the action. OK, the volcano erupting is a pretty good description of what you might see. But the ocean levels weren't supposed to rise that fast. Stories of a woman crawling along dragging the water after her, or of Ngurunderi angrily raising the sea, are dramatic. That's either something that happens within a human lifetime, or something made dramatic by foreshortening. I'm not sure what would jump a shoreline 20 meters in a human lifetime: Lake Missoula draining won't do it (I estimated about 1mm rise from that). That amount of water draining off the glaciers that fast ought to have done dramatic erosion which we don't see. Great glaciers deciding to up stakes and slip-n-slide to the ocean would have turned the southern US into a Canadian Shield. Could 20 meters happen in a hundred years? My geologic skills aren't good enough for me to say.

That leaves foreshortening. What does that mean in practice? Cast back a few millennia. Stories from 1000, 200, 100 years ago illustrated landscape changes that needed to be explained. Assuming the rock formations were already regarded as women, somebody then synthesized the revised story from the old ones. Although this isn't the sort of thing they do, remember? Otherwise how would the details have stayed intact? Which leaves the option that the story was created at that time. It had to start sometime, of course. But the faster the sea level rise was, the less time was required to keep the stories intact, and the if they didn't need to keep them intact long, the more flexibility ancient the story-tellers/memorisers could have had compared to the modern ones.

UPDATE: I forgot about Lake Agassiz, which raised sea levels several meters when it drained in O(8200) years ago, and presumably also the earlier drainages. Not quite 20 meters, but if as supposed it happened over a few decades, people would certainly notice.

Jets of iron

Did you ever, when washing dishes, shove a funnel wide-side-down into the water to see how high the water would jet up from the narrow end? Or, in the tub, put your palms together underwater and quickly squeeze them tightly together, to see how far the water would shoot? When you're dealing the continent-sized chunks of molten and solid iron moving around, it seems you can get fast-moving jets of iron under the mantle. Of course "fast" is a relative term: O(40)km/year isn't going to rival the jet stream, but it represents quite rapid progress through rock.

The image at the site is a little misleading--it's just a toy model of what things might be like. Nobody really thinks there are cylinders like that in the core.

The discovery of the jet involved tracking two massive but unusually strong lobes of magnetic flux originating from the core-mantle boundary, situated beneath Canada and Siberia respectively, but moving with the flow of the molten iron. Because their motion could originate only from the physical movement of molten iron, the lobes served as markers, allowing the researchers to track the flow of iron.

Livermore likens it to being able to track the course of a river at night by watching candles floating on the surface. “As the iron moves, it drags the magnetic field with it,” he says. “We can’t see the flow of iron itself, only the motion of the flux lobes.”

Three satellites sensing the magnetic fields as they orbit the Earth found some variations with time, and it looks like these variations come from the mantle-core boundary.

I don't know if seismography would have the resolution to confirm this.

Earthquake lights

I'd heard of them, but never seen any pictures. Now we even have movies.

No, I don't know what causes this. I guessed that it was electric discharge from large-scale piezoelectric effects as the rock cracks for miles and miles, but that's just a guess.

Look at it.

Slow quakes

It makes sense that the faults slip slowly as well as quickly, but this is something I hadn't heard of before--an intermediate speed slipping, where a change can happen over "days, months, sometimes even years." We can detect some of these now. The really deep ones are, as usual, harder.