Saturday, February 26, 2011

Accretionary Wedge #31 - Wait, What?

As you can see by the title (Wait, What?) the topic for this month's Accretionary Wedge (#31) is surprising geological knowledge. And we had a ton of fantastic contributions to the topic. The official Call for Posts listed the topic headline as this:

What geological concept or idea did you hear about that you had no notion of before (and likely surprised you in some way).
For this month's topic we have a wide variety of entries. From some people that have been blogging for a while, to some newbies (as well as some new to the Accretionary Wedge as well!) and one entry from someone without even a blog!. So remember, what I have for you here is a breakdown and highlights of all the contributions, but to read all of the original entries you must click on the links. Now on to the meat:


Beautiful is what we see,
More beautiful is what we understand,
Most beautiful is what we do not comprehend.
Nicolaus Steno, 1673
The above quote, taken from David over at the History of Geology blog I feel is a perfect introduction into this topic. As scientists we may feel that we know or can know anything if we wanted to but the most fascinating things out there are the things we don't know.

As is the case with my own experience, what I gathered from people's entries is that the majority of people are surprised, not by something completely new or alien to them, but by topics within their own field of study. This should, in part, make sense. Whenever I am surprised by something it is usually because I think I have that information down pat, so when something comes around to completely change my thinking on that, I get thrown through a loop (metaphorically speaking of course) but in the end I come out more knowledgeable then when I went in.

The contributors also had another theme for their entries and it seemed to relate to one of their first major surprise. And these were mostly focused sometime in their early education for when things didn't always make sense. And for some us, still don't.

So, to help make things flow, I have the following entries divided up into topics. Although the topics are somewhat arbitrary, I felt that the basics could be expanded, like metamorphic could also just mean change and so on.

The Fire Realm

Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
Robert Frost, Fire and Ice
The Fire Realm could also be seen as the Igneous Realm. One wrought with not only destruction but also birth.
Jessica over at Magma Cum Laude starts us off into the Fire Realm with a concept she never even thought of before grad school, and that is that volcanic eruptions could vary in style.

"I can’t think of any particular moments where something like this hit me all at once, but one concept that I’ve encountered as a grad student strikes me as something that I never really thought about much as an undergrad (or as a kid who liked volcanoes, for that matter). It’s the idea that an eruption style at a single volcano – not just in a region – can change dramatically in a relatively short period of time.

"My gradual enlightenment to the spectrum of volcanic eruption styles – and the connections between them – is a way that I’ve come to think about about most geological phenomena. While end-member descriptions are useful when you’re first learning about a concept, it’s important to remember that natural systems rarely fit into neat categories, and they definitely don’t stay there."


 Our next entry will be placed into the Igneous Realm since its main competent involves the finding of igneous rocks. And not just any igneous rocks, ROCKS FROM SPACE!!!! Andrew from the Geology Page has a great point that I wanted to start out with.

"Now of course, every concept we ever learn was once a surprise, right? And ideally, a scientist should be able to regard every concept as a hypothesis, held in the mind tentatively and trusted only as far as the evidence goes. The element of surprise should be fresh in the scientist's mind. So we say, but that is very difficult.

"I have to go back to my teen years to recall a surprising truth that still rings today. It was when the Apollo astronauts flew to the Moon and came back bearing boxes of rocks...The experts reported that the lunar rocks consisted of breccia, basalt, anorthosite, norite, gabbro, troctolite. Most of these were unfamiliar to me, and even today I couldn't identify some of them without laboratory techniques. But just the same, Moon rocks had names! They were things we had seen on Earth.

"As an adult I can now tell my younger self, Of course, dude, that's what physics and chemistry mean. They are universal. Rocks are universal. And my younger self answers, Isn't that amazing?"

Processes Realm

The river at the time was fallen away,
And made a widespread brawl on cobble-stones;
But the signs showed what it had done in spring;
Good grass-land gullied out, and in the grass
Ridges of sand, and driftwood stripped of bark.
Robert Frost, The Mountain
  The Processes Realm covers a wide range of topics and could be viewed as the Sedimentary Realm. Most of them focused within different sedimentary environments. David over at the History of Geology blog looks at one of the lesser understood and studied depositional deposits, talus slopes.

"Can a pile of rubble have e name and be studied? Apparently yes - a Talus (term used in North America, borrowed from the architecture of fortresses)) or Scree (English) can be defined as landform composed of rock debris accumulated by mass-wasting processes - or as pile of rubble. But despite this simple explanation, their humble origin, being often neglected during lectures or considered only disturbing in mapping the bedrock lithology, talus slopes are complex geomorphologic features still holding many secrets (not only to me).

"The coarse debris forming the talus can become preserved, and there is ongoing research to use these deposits to interfere the climate of the past. The presence of a Talus as such is not specific related to climate or environment, however the processes (avalanches, debris flows, grain flows) forming or modifying the Talus are depending on the climate.

"Talus slopes are wonderful complex landforms, and being common in the region I work, they still continue to fascinate and intrigue me."


Our next entry is a first for me. This post from Dan comes from someone without a blog (I assume) so he actually posted his entire entry in the comments section of the Call for Posts page. I never thought of doing that but it is a great way to be involved without the hassle of making a blog.

His great post will cause scientists to view dissolving and precipitating minerals in a different light. By witnessing a talk at GSA he saw that the regular views of geology can be turned topsy turvey by that conundrum inducing life processes.

"I hold a PhD in karst hydrogeology and geochemistry, so I thought I was pretty down with how caves form in carbonate rocks… basically, that water containing acidity of some flavor dissolves limestone through an inorganic chemical process of acid neutralization via reaction with an alkaline mineral (calcite). It's like what happens when you take an antacid tablet to relieve heartburn; the calcium carbonate dissolves and neutralizes your stomach acid, and you feel better. Pretty simple chemistry: acid-base neutralization.

"Ok, so those are the basics of cave mineral dissolution and precipitation, or so I thought… that is, until I saw a presentation by Annette Summers-Engel at the GSA meeting in Houston in 2008 on the work she and her students were doing on a cave in Texas. This experiment was so simple, yet so profound…"

Basically what should have happened in her experiment is that calcite should have precipitated while gypsum continued to dissolve but that isn't what happened. The opposite happened.

"Bottom line: microbes eat rocks (sort of).

"More importantly for my field of science, microbes colonizing cave walls can do a lot of the work when it comes to forming caves. And, as it turns out, they do a lot when it comes to the reverse process of forming speleothems and lots of other carbonate mineral deposits as well!"


The next entry into the Processes Realm is by on-the rocks over at the Geosciblog - Science and actually involves something I am pretty well acquainted with, sand. Growing up on an island I rather grew complacent about sand and didn't realize all of the wonders that it held.

"In my youthful vigor, I decided it was necessary to count 500 points per thin section, for about 18 or so thin sections (for my undergrad "thesis"). That "cured" me of a desire for microscope work for a few years.

"After looking for new and interesting lab assignments for my lab classes, I began to spend more time looking through a binocular microscope at sands in general and heavy mineral sands in particular.

"Yeah, with a good supply of heavy-mineral samples, I could stand to be "chained" to a microscope for a little while. So, "Here's sand in your eye."

"I guess the epiphany is that - though I consider myself to be a field Geologist - it would be so easy to get "lost" in the endeavor of peering through a binocular microscope for hours on end."


Change Realm
Most of the change we think we see in life
is due to truths being in and out of favor.
Robert Frost
The change realm could also be seen as the metamorphic realm. Change is one of the only constants in the universe and should be one of the things we embrace as scientists because change in ideas is usually what brings us to better ideas. But sometimes those ideas are a little too far out there. So this is our first Metamorphic Realm entry from Ann over at Ann's Musings on Geology & Other Things. She heard a talk about why the dinosaurs went extinct and although some of it had some merit, the punchline discredited everything else.

"So a few years later, I went to visit another university to hear this guy present his research.  (I wish I could recall his name but it has totally faded from my memory and also the title of his speech.)  At first he was pretty charismatic and came across as being very believable.  He had done a lot of research on the Cretaceous -Tertiary (K-T)(Mesozoic/ Cenozoic) boundary. He theorized that some catalytic event had occurred, which caused the dinosaurs and other animals to have a mass extinction. The mass extinctions had been well documented for quite awhile, but what set his ideas apart was he was claiming that the extinction was due to a single event and not a gradual demise of the animals as it was then believed to have happened.  He pointed out how all across the world there was this dust layer with a radiation marker in it that could be traced which always was associated with the end of the period."

All good science up to this point. But then things get a little...wacky.

"His hypothesis was that the dinosaurs had a nuclear war, and that was why there was this radiation associated with this layer. He then went on and named Tyrannosaurus Rex as the perpetrators of this event. He compared the brain size of a human and the T Rexes and pointed out how much bigger T Rexes were than humans and thus they must have had more mental capacity than man. He had some other data to back up his ideas but this is what stuck with me all these years."

This was eventually followed up buy Alvarez's meteorite impact theory causing science to all but forget the lost dinosaur nuclear war.

"HERE'S SOMETHING TO MUSE UPON -Even though I prefer Alvarez hypothesis and accept it, I keep on thinking back to the the first guy and sometimes wonder what if the first guy is right and the Alvarez hypothesis is wrong. Just a thought. "


One thing that has changed through time is, well, time. Matt from Agile* presents us with his first posting for the AW. So make sure you make him feel welcome in the AW club. Matt describes his experience as a young undergrad learning all about geology.

"Colin Scrutton, one of my professors at the University of Durham in the northeast of England, measured the growth ridges of rugose corals of Middle Devonian successions in Michigan, Ontario and Belgium (Scrutton 1964). He was testing the result of a similar experiment by John Wells (1963). The conclusion: the Devonian year contained 13 lunar months, each lunar month contained 30.6 days, so the year was 399 days long. According to what we know about planetary dynamics in the solar system, the year was approximately the same length so Devonian days were shorter by a couple of hours. The reason: the tides themselves, as they move westward around the eastward-spinning earth, are a simple frictional brake. The earth's rotation slows over time as the earth-moon system loses energy to heat, the ultimate entropy. Even more fascinatingly, the torque exerted by the sun is counteractive, introducing further cyclicities as these signals interfere. Day length, therefore, has probably not slowed monotonically though time.

"For me, this realization was bound up with an obsession with cyclicity... The implications are profound: terametre-scale mechanics of the universe control the timing of cellular neurochemical functions."

Life Realm
And it’s our life.
Yes, when it’s not our death.
You make that sound as if it wasn’t so
With everything. What we live by we die by.
Robert Frost, The Self-Seeker
 Within my own realm, that I feel is related to the sedimentary realm but is uasually lumped into a category all of its own, I have come to the surprising conclusion that life persists, no matter how desolate the landscape may look.

While we were in Mexico we stayed at Puerto Penasco, located towards the northern most tip of the Gulf of California. While we were there we were tasked with the job of analyzing the fauna of different environments in an extreme tidal environment (they have possible the second largest tidal range on the planet, up to 5.2 vertical meters). Growing up on Long Island, I went to the beach often. I always found shells all over the beach but almost never, ever, found something alive besides the birds. Well when you look closely you can find some things alive.
Well, I started to find life. Now I should have known that life would be there but it really surprised me by the amount of life that I found. We found everything from a couple of mini-octopuses, an echinoderm, bivalves, gastropods, starfish, to your everyday birds. All in all, we found and catalogued about ~110 species of animals, most of them alive (or we found at least one alive specimen and lots of dead representatives).

So that is my surprise of information. I did not expect so much life to exist in an area where it looks like there is almost nothing there. Life abounds even when you can't see it, it only takes a careful eye and some time to stop and look at the flowers (or gastropods as the case may be).


Garry, the Geotripper had another experience with paleontology. This one though, going a little further back than mine.
"It took only a split second to take me back forty years to the North Rim of the Grand Canyon, where a 10 year old boy was on his first trip to the beautiful national park. But I had found out something strange at the small visitor center there. The ground I was walking on at more than 8,000 feet had once been on the bottom of the sea! Say what? How could that be? I was already at an age where I had figured out that Noah's Flood couldn't account for this. Where was all the water that it could even cover Mt. Everest and all the other mountains of the world? It was clear that something had happened, but I wasn't quite in a place where I could understand the idea of vast uplift across an entire region. I spent days musing about this, enough that the memory is clear after all these years."
And that experience eventually brought along a fulfilling career.

"It was one of the life-long mysteries (hey, 10 years to a 20-year-old is half a lifetime!) that plunged me into a career as a geologist and teacher. It might seem almost a mundane observation once a geologist has explored the depths of the crust and mantle and the full breadth of geological history, but a first realization is a powerful thing."


Connections Realm

I let my neighbor know beyond the hill;

And on a day we meet to walk the line
And set the wall between us once again.
We keep the wall between us as we go.
Robert Frost, Mending Wall
The next category is the Connections Realm since the previous realms can be combined into their own space. Our first entry is from Dana over at En Tequila Es Verdad for the connections realm has to do with the effect plate tectonics has on the climate.

"But I think the one thing that's made my eyes pop the most is the idea that plate tectonics affects climate.  That shouldn't have taken me by surprise, but it surely did.  Sure, I knew about rainshadow effects - I grew up in the American Southwest, which is deep in the rainshadow of the Sierra Nevada.  Moving up here to Washington State, I could see an even more dramatic example of rainshadow.
"But for some reason, I didn't carry that idea to its logical conclusion: that as the continents go sailing around the world due to the vagaries of plate tectonics, they change everything.

"You know what I think surprises me the most about all this? It's how interconnected all this world is, what an intimate whole all of the different scientific disciplines make. We break them down into categories for convenience, and sometimes forget that you can't have geology without chemistry, physics, biology, hydrology... and you don't get climate without a heaping helping of geology thrown in. You can't understand one thing until you realize it's just a component of a much larger whole. Nothing exists in isolation. It all relates."


Our next entry in the Connections realm I didn't really know where to place but I feel it works best here since it is an overall concept of how the world works (and generally is caused by connections). This is a first AW contribution for Malcom from Pawn of the Pumice Castle so make sure we all give him a warm welcome. His surprising concept is the geophysical phenomenon of Gravity Anomalies!!!

"My physics teachers would drill it into us that acceleration due to gravity is a constant (@ 9.807 m/s2). GRAVITY, G, IS A CONSTANT! ad nauseum. Then I was eventually presented with an alternate view of the consistency of the constant by my geophysics teacher. I, in my infinite lack of wisdom, and stubbornly sticking by what was told to me by my physics teachers, shirked off his silly idea of minute differences in gravity based on crustal thickness and rock types. I didn't really understand the mechanics of it the way he explained it, and it was never really tested on us students.

"The true revelation came during a summer volunteer expedition with a local CGS glaciologist. As one of three heading up to the Matier Glacier within Joffre Lakes park, I got a taste of what experts do, and what instruments they use to analyze receding glaciers and the mountains they rest on. I found out that one such device we lugged up to the top, a microgravimeter, measures the gravitational field at a point. So the glaciologist operated it, got the reading in milligals, and I stood there dumbfounded.

And he sums this up with a feeling I'm sure a majority of us have had:

"In retrospect, I wish I had a time machine, so I could go back and tell my junior undergrad self about how not to take anything for granted in the scientific studies. Geology always seems to smash preconceptions built up by the other science disciplines, and that's something I love about it."


Our next in the Connections Realm is Matt from Research at a Snail's Pace and he looks at the very very large and compares it to the very very small. And I think he finds some interesting things there.

He starts off by scaling down the solar system to be a total of 1000 meters across (from the sun to Neptune (poor Pluto)).

"The sun ends up being a little larger than a basketball. Earth is about the size of an "airsoft" BB pellet. Jupiter is a little smaller than a ping-pong ball. Now imagine holding the basketball-sun and looking down the walkway and just seeing the football field in the distance a thousand meters away. Resting on that far goal post is a marble. That marble is neptune.

"Pretty cool. But it works the other way too. What if we were to take an atom of gold and scale it up so that we were holding the nucleus and the outermost electrons were on that goalpost? The nucleus would be just a little larger than a baseball. The electrons, all 79 of 'em, would be little BBs orbiting in clouds. Technically, electrons are "point" particles with no actual physical dimensions of length, width or height.

"And now for the mind-bending part if we tally up the mass of all the stuff in the solar system, the sun accounts for about 99.86% of the total mass in the solar system. If we tally up all the mass of the neutrons, protons (each being about the size of a marble - one inch in diameter), and electrons, the nucleus accounts for 99.98% of all this stuff. Proportionally, there's more than six times more mass outside the sun than mass outside an atomic nucleus.

"There is more space in stuff than there is stuff in space!"


Unsolved Mysteries

The woods were lovely, dark and deep.
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep.
Robert Frost, Stopping By The Woods on a Snowy Evening

And lastly we have an interesting one and one that has confused me from time to time (when I have time to think about it). It is presented by Ian over at Hypo-theses and unlike the other entries, this one remains a unsolved mystery (hmm maybe another AW topic?). It is, how do plastic earthquakes occur?

"Shallow earthquakes are relatively straight forward. Stress builds up in a block of rock containing a fracture, whose two sides are held together by friction. Eventually the stress overcomes the friction and the two sides either side of the planar fracture move past each other, releasing the energy that had been stored previously as elastic deformation in the rock mass neighbouring the fault. The system of forces acting at the source is well known and described as a “double couple”. "

"The model is fine for shallow situations where the rocks are brittle. However, the temperature increases by about 30° C for every kilometre you go down. In areas like California where heat flow is moderately high, by the time you get to about 15 kilometres down the rocks are too soft to deform in a brittle fashion and instead flow plastically. In intraplate areas like the UK where the heat flow is less, the brittle-ductile transition is just over 20 km.

"So we have a geological conundrum. How is a material that should flow plastically accumulating enough stress to generate a magnitude 8.3 earthquake such as the one that occurred on June 9, 1994 636km beneath Bolivia and generates a shear mechanism indistinguishable from a shallow earthquake (other than perhaps by rupture velocity)?

"There has to be some processes (probably involving mineral phase changes) that can cause some shear instability runaway condition that generates a supershear, rupturing at fast velocities generating deep earthquakes in a plastic material. What that process is uncertain, and something we may never know."

Final Thoughts

So there you have it. We have a range of surprises from what may seem like everyday knowledge to the surprises still surprising scientists today. My word of advise is similar to that who have contributed, don't be afraid to be surprised, sometimes you find the the most amazing information that way. And I would like to thank and welcome all of the new bloggers and first time contributors. Keep up the good work.

Any late posts or posts that I might have missed, please let me know and we will get you added as soon as possible.


  1. Great Wedge - lotsa cool stuff here. Thanks for hosting!

  2. Thanks for hosting, you did a nice job putting it together. I thought it was a great topic.
    I especially like the quotes of poetry to tie things together.
    I hope you had as much fun putting it together as I did reading everything.

    It's so exciting to see the new contributors. Welcome Aboard!!!and thank you. I look forward to seeing more things from them/you.


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