Author Archive

Accretionary Wedge #33: Geology and the Built Environment: Past, Present, Future

April 20, 2011

Cross posted from Geological Musings in the Taconic Mountains

I tossed out the topic of how geologists et al. have or would like to incorporate aspects of their professional and personal passions into their built environment. The response was varied and it was intriguing to discover where folks ‘see’ geology. If you’re like me, you probably tell your students “geology is everywhere” and that claim was only strengthened by the response to this month’s Accretionary Wedge.

Anne from Highly Allochthonous illustrates how she uses her backyard for a geologic purpose rather than altering it to serve her own aesthetic interests… either she has higher morals about terraforming backyards or she wins the geo-nerd award for encouraging citizen science with her daughter. Her description of the dangers associated with conducting science in your backyard will make you smile and illustrates how something as simple as a bucket of water on monkey-bars can be extrapolated back to calculating isotope hydrology… and wow that analyzer is small!

Geology Happens describes two different scenarios involving landscaping of a sort; one that recreated the stratigraphy of the Canyonlands and another where someone incorporated an iron concretion into a retaining wall in Zion National Park. I can’t help but wonder why we don’t see more of this type of creativity, government rules, lack of inspiration, lack of time? It certainly can’t be a lack of interesting rocks!

Dana from En Tequila Es Verdad offers inspiration for letting your rocks out of their boxes and displaying them proudly… everywhere! Her apartment looks like a clean version of the rock room’s we all browsed as undergraduates (minus the crystal models of course). She even has zen garden incorporated into her fractal-esque approach to interior landscaping. I think it’s time we all brought some of our samples locked away in the office back home!

On-the-rocks follows suit with a similar mosaic-like approach to outdoor xeriscaping, describing the significance of the rocks and stones integrated into his retaining walls and patio. He has incorporated his passion for geology with the concept of ‘Found Art’ by making use of stones collected from previously built structures. A fascinating synthesis of aesthetics with wonderful stories related to his great-great grandfather. I hope he doesn’t have to part with his collection any time soon. His stories strike a chord with my contribution to this months AW, where I finally provide visuals for the way my father integrated rocks into the house I grew up in.

Hypocentre at Hypo-Theses tells a sadder tale of having his rock garden ‘banished’ outside, left to summer the ravages of time… okay, I elaborated a little and they are rocks, so they will survive. While his gardens appears to be a little smaller, the diversity of rocks and the stories (many, yet to be told) tied to them are as varied as they are obscure! I also think you’ll enjoy the wonderful textures created between the rocks and the just as varied ‘shrubberies’ growing among them. I hope we can convince Ian to elaborate on his rocks more than the rock of the day blurbs, I know there is more to tell….

Ann from Ann’s Musings on Geology & Other Things takes us back inside and describes a seismic event leading to a new table top and how she created a xenolith in her house. Actually the seismic event was her son providing her with an opportunity to upgrade to serpentine table tops. Her experience illustrates the need for one of us to write a “Field Guide to Commercially Available Building Stones” so everyone can correctly identify rocks… Her xenolith was created when she had slate with two slightly different tones installed in her office. Tell me I’m not the only one who saw a xenolith hiding in the floor?

Silver Fox from Looking for Detachment brings us back to our roots by describing her desire to live in a stone ‘hobbit-like’ cottage tempered by her acceptance that having rocks in her backyard is just as satisfying – and safer in earthquake country! I may read to far into her ‘message’ but I think it’s appropriate to claim that no matter how many rocks we collect, stack into neat little piles, turn into furniture, hold back sod, etc, etc., we all prefer our rocks in their natural habitat. Where they challenge us with their complexity, provide a substrate to play on, and a library to learn from.

AW#33 Call for posts

March 28, 2011

I’ve always wondered how crazy other geologists have gone with incorporating geology into their homes, offices, gardens, etc. I know we all have a mini rock collection on the shelf, or a rock holding open a door but I’m thinking bigger. For example, I haven’t done it yet but when I build the next house, all the window sills will be made out of slate. Share your stories, descriptions, photos of your current or past geology-related embellishments and I’ll summarize.

The deadline for this is April 17th, I’ll summarize on the 18th. Please post your contributions in the comment section, thanks!

Cross posted from Geological Musings in the Taconic Mountains.

AW#32 – A parade of geological images

March 12, 2011

Hosted by Ann’s Musings on Geology & Other Things

It’s carnival time in the south and since the Accretionary Wedge is suppose to be a carnival of blogs and information I feel it is only fitting that we should have a parade of favorite geologic pictures to post. I’ve posted them in the order in which they were received.
Thank you all for participating and making it such a wonderful parade.


We will start this parade with some parade music to get into the spirit while you look at the wonderful pictures.
Here’s ’76 Trombones Led the Big Parade’ from the movie ‘The Music Man


First of is Dana with the float from   En Tequila Es Verdad

Dana had a hard time picking on a favorite photo, so instead she picked a favorite geologic place to go to.  Can’t you imaging yourself going there for some peace and quiet?  Isn’t it a fantastic place to visit?

Here’s a little of what she wrote:  ……. we’ll do this.  We’ll cut to the chase and play a favorite – a favorite place, one of my favorite places in the world.  We’ll take a trek through the desert and come upon an oasis.

Montezuma Well, ambush shot by Cujo

Down around Camp Verde in Arizona, you’ll come across a picture-perfect karst terrain.  The old beds of lake-deposited limestone lay flat, dry and hot under the sun, carved into gullies and hills by wetter times.  In some places, sinkholes pit the scenery.  They’re lovely examples of the power of water and gravity together to sculpt the scenery.

Camp Verde got its name because a river runs through it, causing a line of green to conga through the hot, scrubby hills.  It was enough of a shock that explorers named it the Verde River, because it was very nearly the only green thing they’d seen for absolute miles.

You will have to go to her blog to read more about this delightful place.

The old Sinagua canal

She ended with and I agree:
Now that you’ve had a nice rest at the water’s edge, on with the parade!


Jim has two pictured of the fascinating Gooseneck of the San Juan River for his float at

The Geology P.A.G,E.

Well since I have done this for a previous AW, I will switch up the picture I used and this time give you a couple of glimpses into the Gooseneck of the San Juan River.

Gooseneck of the San Juan River

Matt’s float is here at Research at a Snails Pace
with a breath taking view of the island of Maui, Hawaii.
(I’m having trouble with this link so here’s it is )

He writes:
So here’s one of my favorite pictures – Haleakala crater. Technically, this isn’t the actual crater, it’s the eroded summit, widened by erosion. The smaller hills are cinder cones that erupted after most of the shield volcano was eroded away.



Here’s the float from Jessica at  Magma Cum Laude with this beautiful picture.  She writes:
One of my favorite geologic photos is plenty colorful – and it’s also from my first field course, a month-long tour of the Colorado Plateau. The contrast between the sand and sky at Coral Pink Sand Dunes State Park in Utah is truly striking, and it was one of my favorite stops on the trip – because it’s also an excellent place for a game of frisbee!


From Evelyn we have a first time entry for the AW.  Welcome aboard Evelyn!!!  Here’s her  float from Georneys

She writes:
One of my favorite geology pictures (I have several- so difficult to chose!) is a picture of my favorite campsite ever. The picture below shows a makeshift campsite just off a road in northern Oman. The beautiful mountain in the background is Jebel Misht, one of several exotic limestones in the middle of the Samail Ophiolite. I was lucky enough to spend a few nights at this campsite in 2009 and 2010 as part of my PhD thesis fieldwork. One of my field sites, located near the small village of Al-Bana and close to the Misht campsite, has been named “Jebel Misht Travertine” by my research group.

Jebel Misht is a popular climbing destination. Making your way up the tall southeast cliff is not an easy task.  When a French team of climbers accomplished the first successful ascent of Jebel Misht in 1979, the Sultan of Oman arranged to have the climbers picked up by helicopter from the top of the mountain and whisked off to the palace for a celebration. Jebel Misht means “Comb Mountain” in Arabic. Indeed, the mountain’s majestic cliff resembles a gigantic comb resting peacefully amidst the seafloor rocks of the ophiolite.

I am glad she came up with something and has joined the parade!!


From the float at  Mountain Beltway Callan has these interesting things to say:

He writes.…. While it’s not my favorite, it’s definitely a favorite, more by virtue of the geology it shows than the aesthetic qualities of the image:
That is an outcrop of the French Thrust, one of many imbricate thrust faults exposed in Sun River Canyon, Montana, just west of Augusta. The light colored rock at right is limestone and dolostone of Mississippian age, and the dark rock at the lower left is shale of Cretaceous age (deposited in the Western Interior Seaway). Beyond that, to the very far left, you can see some lighter-colored, poorly-sorted material. That’s Pleistocene glacial till, and both the shale and the till are capped by a sloping layer of colluvium, tumbling down from higher elevations. The contact between the shale and the dolostone is a thrust fault. Half a mile downstream there is another. Half a mile upstream there is another. There are a lot of them exposed in Sun River Canyon, and the Canyon cuts across strike of all of them. Note the syncline in the Mississippian carbonates, and the differential weathering of the carbonate (tough, proud) as compared to the shale (weak, depressed). Here’s an annotated version of the photo:

The Sun River Canyon is an unparalleled location in my experience for gorgeous scenery, great weather, a minimum of people, a healthy population of great gray owls, and exceptional exposures of an imbricate stack of thrust sheets. Check out this old post I put up at Pathological Geomorphology for more details about the area.


Helena’ float at   Liberty, Equality & Geology has this wonderful  panorama for her float.

It’s always hard to pick a favorite geology picture, but this wintery Crater Lake panorama tops my list right now. Crater Lake is one of my favorite places, and it was exciting to visit in the winter! The perfect mirroring effect was particularly stunning. In person, the sky and water were the same color, making the caldera look like an arch in the sky.


Julia has a very intriguing float from  Stages of Succession .  You need to make sure you get a good look at what you are seeing.  Please go to her blog to figure out if you are right or not.


Gareth’s float at  Science 2.0 is very interesting to see because it has a volcanic bomb in it.  This is one of the few bombs I care to see.  In fact I wouldn’t ming going to Satorini to check it out for myself.

Volcanic bomb on SantoriniDespite my relatively short career as a geologist, it was a hard choice.  There was a spectacular fault outcrop in Arkitsa, Greece; some impossible-looking resistant beds sticking straight out of the forest near Benés in the Catalan Pyrenees; and the classic ‘ripples on a vertical surface‘ to illustrate tectonic forces, also in the Catalan Pyrenees.  However, I decided on this photo in the end, mainly because now I am a proper volcanologist I felt I should choose a volcano-related picture.

The photo is from Santorini, and shows a volcanic bomb.  The layer it has impacted into is about 2m thick.  While this is far from the largest bomb on the island, the way it is exposed here really does emphasise the power released when a volcano decides to blow.


Now we are going to go to On-The-Rocks float at  Geosciblog – Science
He wrote:

The Eagle Mts. (an Oligocene caldera) were the site of my originally-intended Master’s Thesis work, during the summer of 1978. The photo here was taken from the East Mill area, where we camped, for several weeks, while we mapped the southeastern portion of the mountains. In the near foreground is a portion of Wyche Ridge, composed of Cretaceous sedimentary rocks, forming part of the margin of the caldera.
Please go to his blog to read the rest of what he has to say about this area.


Here’s more music for a half time break ‘I Love a Parade’ by Lawrence Welk


John’s float at  Geologic Musing in the Tactonic Mountains has this wonderful text book example of an angular unconformity.  (I am having trouble with his link so here it is )

This what John has to say about his picture:
Last summer I drove out to Bozeman, Wyoming for a GIS conference and took a rather circuitous route both outward from and back into Vermont. We decided to camp at Buffalo Bill State Park along the reservoir and then return to Cody after setting everything up. On our way back into Cody, just before the famous rodeo stadium, the setting sun illuminated this fantastic angular unconformity exposed in the Shoshone River. Based solely on the descriptions found in Torres and Gingerich (1983) I think the lower reddish unit is the Eocene Wildwood Formation overlain by the volcaniclastic Aycross Formation. I haven’t done any work at all, so this is solely based on reading geologic descriptions, hope I’m close.


View Angular Unconformity in a larger map
And here is a closer view of the contact; again I ‘think’ my interpretation is correct but please advise if I’m off base here!



Ian at Hypo Theses has another fascinating picture of distant shores for his float.

John wrote:……It shows the foreshore at West Angle Bay, Pembrokeshire, Wales. The view looks westwards towards Milford Haven and shows the Lower Carboniferous Limestone contorted by a series of Variscan thrust related folds. One of the thrust planes is seen in the left of the image, over-steepened by the folding. To the centre of the image are a pair of whaleback periclinal anticlines. The beds then steepen again to vertical on the right via a tight syncline.
But the beauty of a gigapan image is that one can dive in and view the detail like the slickenside lineations on the thrust plane or the writing on the buoy.


Garry float at Geotripper is still spectacular even though it is at a place that’s been photographed many a time.  (I’m having trouble with his link so here it is  )

Long before I had a digital camera, I used a particular slide from a trip in the 1980s to introduce my students to the idea of the fascination of geology. It was taken next to one of the most famous photography spots in our national park system, but it is not a picture of the iconic feature. It’s the trail leading to it. Delicate Arch of the “Real” Jurassic Park lies just around the corner, and a crowd is often found there, especially at sunset. But I see fewer people stop and consider this scene….

I got into geology in part because of the wonderful journey of imagination that it is; a geologist is a world traveler, and a time traveler. The trail in this picture is formed on a natural break in the rock. Why is the break there?

In Jurassic time 180 and 140 million years ago, tidal flats and coastal sand dunes spread across this part of Utah. The surfaces of the dunes were pathways for all kinds of creatures, from insects to giant lumbering dinosaurs. The walked and crawled on these sands, and later the surfaces were preserved by subsequent layers of windblown sand. The surface later hardened a bit more than the others, and millions of years later, erosion exposed the old sands. A fracture developed along the surface, and the trail-builders of a few decades ago found it a great deal easier to just remove the overlying rock than to carve a new flat surface at great expense. And so it is that during our brief sojourn on the planet, we walk on the same surface, and perceive the significance of that fact. We use our minds to explore strange alien worlds, and yet these are the worlds that existed before ours and which became the raw materials for our own.
Again, practically everyone walks up to Delicate Arch, but there is another arch just a few steps off the trail that provides a stunning view the distant La Sal Mountains, the laccolithic cores of 25 million year old volcanoes. This picture, taken just a few yards from the one above, contains the four elements of ancient human thought: water, earth, fire and sky (the water is in the sky and in the creek below). The essence of earth science…


Reynardo’s float at  The Musings of the Midnight Fox has a very interesting one with this to be said about it….

Charleston Cave

This one is from New Zealand. The Nile River Caves (as featured in WOGE #263) are on the north-west side of South Island, New Zealand, and as well as the expected beautiful limestone features, have some wonderful glow-worms and some rather interesting strata.

This one in particular is a mixture of mudstone and limestone. By the time this layer emerges at the coast at Punukaki, it’s more clearly layered and makes the Pancake Rocks.

Yes, I have amazing glacier and volcano shots. But this one is the one that says “Geology” to me the loudest.


The float Elli has submitted at  Life in Plane Light has this amusing tale to tell…

For my PhD research, I ended up working in the Swiss Alps.   Day one out was long, long, long (and it was magically also my birthday).   By the time we reached the col that was going to actually become my field area it was rather late in the day and we were still 1000 m above the closest road.   Bridget (my field assistant) and I were wearing every item of clothing that we had in our packs due to the cold (there was still snow on the ground & it was July).   Before we could call it a day, we decided to collect four samples (we had a number of other rocks from earlier at other sites to the south of the col).   Three popped out without an issue in reasonable sizes (enough for thin sections, tomography, and bulk chemistry), but the fourth was stubborn.   It came off in a huge sheet:

the large slab (behind the hammer) that eventually became 04AD15; Tom Foster in blue, Hannes Hunziker in the middle, and Lukas Baumgartner in pink
while Bridge and I proceeded to shiver, these three male geologists tried to get 04AD15 down to a reasonable size.   They used the sledge.   They used a hammer with a chisel.   They hopped up & down on the slab.   They wedged another rock underneath the slab and tried everything again.   Eventually, pieces started to fall of the edges.   In the end, 04AD15 is still my largest sample.   But its also my best sample of the bunch (including what I got a year later!), so all that work was worth it.   But whenever I look at anything related to the sample, I have to imagine three senior geologists trying like crazy to break the slab :)

04AD15 post-cutting


Michael with Through the Sandglass has apiece of art as his geologic float

Accretionary Wedge # 32

The March edition of the Accretionary Wedge geoblog carnival is at Ann’s Musings, and the theme is a deceptively simple summons: “Throw me your ‘favorite geologic picture’ mister.”  This is nigh-on impossible and has led to some considerable introspection, not to mention scrabbling around to see what candidates I have with me on my laptop. But the scrabbling stopped as soon as I reminded myself of the image above. At first glance, perhaps it’s not strictly geological – but then again, yes it is. And, because of the very personal impact, it’s one of my favourite pictures – ever.
It’s from a location in the remote south-western corner of Egypt, a Louvre of rock-art. This is just a small exhibit in a cave shelter covered in human expressions. The setting is geological, the canvas is geological, and the materials are geological, and all combine in the message of the connection between humans and geology. But of course it’s even more than that – we have no idea really who the artists were, exactly when they lived, what the function of this place was in their society, or why they expressed themselves so exuberantly. But the emotional  resonance, sitting there gazing at this, has become deeply ingrained; there is an immediate, intensely human, connection with two unknown people who chose to record their hands reaching out to each other.
It’s not even a picture of sand – but it is probably my favourite geological photo. And, in today’s world, perhaps it has an important message.

Here’s the  History of Geology interesting float by David.
( I’m having trouble with this link so here it is )

In a first moment I couldn’t decide what image to take, the classic outcrop or the marvellous landscape? – but there is an elder picture of 2007 I really like, at a first glimpse it’s geological context is not obvious, but this is also a reason that I like this particular picture.

The photo shows a species of club moss emerging from a pile of rubble. The club moss Huperzia selago is one of the two species of this genus present in the Alps; this species in particular can be found in high altitude and in glacier forelands, acting as pioneer species.
This specimen was emerging from gneiss and schist debris covering an active rock glacier; I like the contrast of the green plant to the cold grey of the rocks forming a sort of picture frame, the impression that the club moss overcomes every obstacle, even “breaks” the rocks apart to emerge from the underground.
For plants creeping debris and permafrost represent an ulterior challenge for colonization and growth in an already nasty environment, with long snow cover, low temperatures and deadly UV-radiation. I think the picture depicts well the struggle of existence in a harsh environment – but as the the rocks act as obstacle they at the same time also provide shelter, moisture and nutrients.

For the geologist also the recognition of even the smallest clue can be helpful, I find it fascinating how many different methods can be adopted to understand the development of a geomorphologic feature or a landscape – in combination with classic geological methods for example the vegetation cover or diversity can give indications of the recent activity of rock glaciers, or help to reconstruct the temporal development when other indicators are absent.

And finally the image remembers me as a sort of metaphor what the German geoscientist Gerd Lüttig argued in 1971:

Earth history can be described as a permanent interaction between the geosphere (lithos) and life processes (bios). To investigate these processes is the mission of Lithobiontics, a new research discipline between Geology and Biology.


Here’s Philips float at   Geology Blues is not only spectacular to look at but is special to for the memories it hold for him.  (I’m having trouble with this link so here it is  )

In a post about Multnomah Falls and Columnar Jointing, I posted this picture taken of Sam at Devil’s Tower a few years ago. It remains one of my favorite pictures of geology (and Sam) as it provides such a great image to show several geologic principles at ones. Aside from the geologic signficance of the tower itself, the promionant geologic feature is the massive hexagonal piece that 7-year old Sam (for scale) is leaning against. Behind it, you can see the joints extending up the tower with clear hexagonal blocking roofs, allowing one to recognize the block as having weathered and fallen off the tower.

The picture also has trees and shrubs growing in the fractures below the main part of the tower. These fractures are not the columnar jointing of above, and so demonstrate a different condition of cooling for the base of the tower. The fractures below also have trees and shrubs growing amids the fractures illustrating yet another form of mechanical weathering.


The float at  Geology Happens has this wonderful panorama view.
(I’m having trouble with this link. )

This was taken from the appropriately named “Anticline Overlook” of the Canyon Rims Recreation Area in eastern Utah. The anticline is obvious, you can see the upward curve of the rock units. I love the part where the river cuts through the anticline making a natural road cut.

The river cuts through the Permian age Cutler formation, the left overs from the formation of the Ancestral Rockies. The upward arching of these rocks is from the squishing (a very technical term) of a buried salt layer. Far below the Cutler lies the Pennsylvanian Paradox formation, a mile thick layer of salt that has a tendency to move about creating some fun landscapes in the desert southwest. The buildings and ponds you see in the picture are a potash mine. Water is pumped underground into the Paradox layer, dissolves the salts and the brine is pumped back to the surface into the blue evaporation ponds in the background. The water evaporates away leaving the salts for transport.

The fun part of this area are the roads. They are barely visible in the picture but they travel hundreds of miles through the red rock desert . A mountain biking heaven!


Cain at  Point Source has added this last entry to the parade of picture floats.
(I’m having trouble with this link so here it is  )
In the midst of reorganizing, I recently unearthed some deeply buried personal geologic records from past research projects.  One discovery was an image that previously adorned my wall:  a MagellanVenus. radar image of arachnoids on

Magellan radar image of arachnoids on Venus. (Image courtesy of  NASA/JPL)

Magellan radar image of arachnoids on Venus. (Image courtesy of NASA/JPL)

I think this image is a perfect fit for Accretionary Wedge #32 “favorite geologic picture.” It’s not the most colorful or dramatic image, but it holds an important place in my professional experience in the geosciences.
Arachnoids are geological features on Venus. They are characterized by a combination of radar-bright, concentric rings (like a bull’s eye) and radiating lineations (line-like features) and were named “arachnoids” because of their spider and web-like appearance.
Although these features had been identified on earlier Soviet Venera mission data, the NASA Magellan mission provided sufficiently high resolution radar imagery and elevation data to investigate them more closely.
These features were one of my first forays into geology research as an undergraduate student. What were they? Did all features catalogued as arachnoids based on the radar images have similar topographic features? What caused them? Where they all the same age? Where were they located? Was there a terrestrial geology analog? I had many questions, a patient research advisor, and a short summer.
The personal outcome was clear, though: I was hooked. Geology was fascinating, no matter where in the solar system. There were so many questions, and we didn’t have all the answers!  This was a far cry from the textbook science of packaged information and rote facts to memorize. The science was alive, the questions infinite, and the data plentiful.
Whenever I see these data images, they represent all of this in one snapshot: the excitement and mystery of geology.
He has more but you just have to go to his blog to read the rest of it.


And finally here’s the Captains float –
The Red River at sunrise, seen from a balloon about 1000 feet up in the air.

The Red River
The beads are thrown and are now on the wire connecting to the internet web. I hope you had a good time.

Now all good things must come to an end.  The parade is over and it is time to go home.  Thank you one and all for submitting something for this Accretionary Wedge – 32.
If you had something and didn’t get it in  or if I missed it please leave a comment and I will add it later.

Post script:
Here’s a little bit about Mardi Gras for those who don’t celebrate it like we do in Louisiana.

For those of you who don’t know its officially Carnival time or Mardi Gras season  (Twelfth night to Fat Tuesday i.e. Jan 6 to March 8 this year).  Twelfth night is also know as the feast of the Epiphany and is celebrated by Christians as the day the three wise men came to visit the baby Jesus and is 12 days after Christmas.  Fat Tuesday is the day before Ash Wednesday.  Ash Wednesday is the first day of lent, a  time where you are suppose to make sacrifices and give up things, in preparation of Easter which is 40 days later. Because people may give up drinking, certain foods etc for the forty days during lent they like to have a big blow out where they consume the food that they will be giving up.  They usually do this the day before and thus the reason it is called Fat Tuesday or as the French call it Mardi Gras.

To celebrate together different groups of people with like interests get together and form Krewes.  Most Krewes have a theme by which they go by. For example, in my area of LA there is a Krewe of doctors call Aesculapius and another one for Lawyers called Justinian and one of cat and dog lovers called Barcus and Meow.  I am a member of the Krewe:  Les Femmes Mystique.  If you haven’t guessed it – its a group of women who are concerned about the community.  Although we enjoy our parties we also like to give something back to the community.  Every month we have a project to work on.  This keeps the Krewe together during the year when the parties are not going on.  Every month there is a different project, such as working at the food bank, help run the Susan G Coleman race for cancer, the march of dimes walk, gathering school supplies for children, getting and wrapping toys for the Toy’s for Tots program, etc. It varies from year to year what all we do.
But the thing that most people know the Krewes by are by their parades.  My Krewe is not big enough to have a parade of their own so we augment other parades in the area by joining in on other floats in the parades.  When you are on a float, you provide all of your own throws – the things you toss to people.  People love to come and watch these parades because of the gaudy decorations and the stuff that gets tossed to them.  Beads are the most common thing, but there are also other things tossed to like stuff animals, wrapped candies/food, plastic cups and fake coins called doubloons (which can become a collectors item).  It’s whatever you want to buy and spend, but you are restricted to things that can’t hurt if tossed, also it can’t be offensive to the public in general.
If you ever go to a Mardi Gras parade there are certain things you should know.  Namely they can’t throw anything if the float is not moving, so don’t try to stop a float to get something from it.  Also if it lands on the ground put your foot on it and then after the float has gone by then reach down and pick it up.  If you try to reach down and grab it expect someone to stomp on your hand.  Also when the float goes by everyone says ‘Throw me something Mister’.  The reason they do that is because the people on the floats are usually in costumes, with their faces covered.  They cover their faces so they can remain anonymous.

Elaborate costumes are common with the Carnival.  Most Krewes have a King, and a Queen and a Captain the rest of the float leaders are called Dukes and Duchess. Because they are royalty they like to dress up to the part, thus the elaborate costumes.  These people hold their offices for one year, and then switch off at coronation Bals. There is also another bal that is thrown during the Carnival time where the other royalties come together to enjoy the hospitably of the different Krewes. The Captain of the Krewe organizes the bals and parade and is the person who is in contact with the other Krewes.  The King and Queen are the official representatives of the Krewe for that year and are expected to attend most events.  The King and Queen are very rarely married to each other.  The spouse or significant other of the Royalty person is officially named their consort.

Mardi Gras is all about having fun and celebrating life.  It is also about giving back to the community in which they live as a ways for friends and neighbors to get together so they can get to know each other better. For more about Mardi Gras here Wikipedia Mardi Gras.

Post Script:
I do want to thank everyone.  I did have some technical difficulties with this but eventually figured things out.  I do want to thank Callan for helpful suggestions, while I tried to get it done.  I must admit I agreed to be a host more for my own benefit than yours.  I’ve very inept with computers and doing things like this teaches me so much. I also do it so I can see all the amazing things that have developed in the geology field since I was last active in it. I enjoyed putting this blog together and it wouldn’t have been possible if it wasn’t for all the contributions I got.  Again THANK YOU.

March 9, 2011

Here are the topics and hosts for the next 4 editions of the Accretionary Wedge:

#33 – April – John Van Hoesen of Geologic Musings in the Taconic Mountains hosts. He asks, “How much or what kind of ‘geology’ have you incorporated into you home / living space?”

#34 – May – Dana Hunter of En Tequila Es Verdad hosts. The theme is “Weird Geology.”

#35 – June – Evelyn Mervine of Georneys hosts. The theme is “my favorite geology word.”

#36 – July – “Ontherocks” of Geosciblog-science hosts. The question is: “What past mineral/fossil locality have you regretted not collecting more specimens from?”

Thanks to these geobloggers for volunteering to host. If anyone else wants to claim a future Wedge, let us know when and who and what via the comments.

Who’s next?

March 6, 2011

Hi there,

The Accretionary Wedge has seen a resurgence of activity lately, and we’ve had three Wedges crammed into two months. But who’s on deck to host the next one?

#33 – April – John Van Hoesen of Geologic Musings in the Taconic Mountains hosts. He asks, “How much or what kind of ‘geology’ have you incorporated into you home / living space?”

#34 – May – Dana Hunter of En Tequila Es Verdad hosts. The theme is “Weird Geology.”

#35 – June – Evelyn Mervine of Georneys hosts. The theme is “my favorite geology word.”

#36 – July – “Ontherocks” of Geosciblog-science hosts. The question is: “What past mineral/fossil locality have you regretted not collecting more specimens from?”

Let’s hear from you, especially if you haven’t hosted before, or if you haven’t participated in a while. Come up with a theme, and then put it out there on your blog (leave a link here), and see what sort of cool stuff you inspire in your geoblogging peers. Who’s in? What are your proposals? Leave a note in the comments on this post — I’ll update the post with volunteer hosts and topics as they come in.

AW #32 – Reminder and final call

March 5, 2011

Ann reminds us that the deadline is coming up for the March edition of the Accretionary Wedge geoblog carnival:

I just want to remind people of the call to post for AW-32 at
It’s carnival time and I want to have a parade of the different geoblogs.
It’s a very easy one this time with “Throw me your ‘favorite geologic picture’ mister”. The parade will take off on March 8th. If you haven’t submitted anything please do. Every Krewe’s parade uses other groups to make the parade special so even if you don’t have a blog you can still get stuff to me via my email @ I’m still accepting items.

#31 Wait, What?

February 26, 2011

The new Accretionary Wedge is now posted at the Geology P.A.G.E., courtesy of Jim Lehane:

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.

AW#31 — reminder and final call

February 18, 2011

Jim Lehane reminds us that it’s time to get in your submissions for the Accretionary Wedge’s 31st edition.

Last Reminder – AW #31 due Tomorrow (ish)

Just wanted to send out a last reminder that this month’s Accretionary Wedge (#31) is due tomorrow. I will accept the initial run of posts up through Sunday though (since I likely won’t have time to compile anything before then). But any late posts will be added afterwards.

We have some great entries so far, so make sure you don’t get left out. Please leave a link to all posts on the original Call for Posts page.

Accretionary Wedge #30: the Bake Sale

January 31, 2011

(cross-posted from Mountain Beltway)

I hope you’re hungry, for the 30th edition of the Accretionary Wedge geo-blog carnival is all about food. It’s the Bake Sale! Let’s start our feast with something substantial, and only then move on to the dessert smorgasbord.

Andrew Alden, geology guide at, has all kinds of ideas on the relationship between geology and food. If you’re not sure if you’ve got a potato or a meteorite, then check out some of his geologic recipes for kids on this page.

Perhaps some meatloaf would make a proper main course. Ron Schott thought so, and on Ron Schott’s Geology Home Companion blog, he baked a meatloaf in the shape of a roche moutonée, those glacially-sculpted bumps of bedrock. I love how the bacon strips mimic the glacial striae; Only thing could make this meatloaf better… and that’s if the “meat” were mutton, to better match its geomorphic model’s namesake. Here, I’ve annotated one of Ron’s photos to show the glacial ice with the flow direction moving over this chunk of savory goodness:

Accompanying the meatloaf should be something starchy. Matt Kuchta showcases the mechanical properties of (uncooked) pasta in a post on his blog Research at a Snail’s Pace. There, in images and video, he shows us about elastic rebound theory, but the final frames of the video (wherein he eats uncooked pasta) don’t make it look all that appetizing.

Another possibility is bread. Here, in German (but with lots of pretty pictures) is a post from Lutz Geissler that basically argues that bread loaves mimic the shape of lava pillows. (Lutz usually blogs at, for those who don’t know.)

Kathy Cashman and Alison Rust were thinking along similar lines when they penned a guest post for Earth Science Erratics on vesicles, lava bombs, and sourdough bread.

Anne Jefferson of Highly Allochthonous brought the final healthy dish to our potluck. She made a veggie pilaf with broccoli, onion, rice, lentil, potato, portabella, garlic, pepper, salt, coriander, ginger, and barley. Then she set it up on an oversteepened slope, and let ‘er rip. The result was a miniature debris flow that showed some patterns that mimicked natural mass wasting events.

Dana Hunter (who writes En Tequila Es Verdad) also focused on surface processes with her contribution. She baked a glaciated cake to depict the geomorphic processes which yielded her neighboring Cascade Mountains.

Jim Lehane brings out our second dessert course with a neat comparison in the shake-ability of Rice Krispie treats versus Jello: Which dessert is better to build the foundation of your house on? Follow the recipe for disaster (“dessertaster?”) at The Geology P.A.G.E.

Helena Heliotrope, who writes the blog Liberty, Equality, and Geology, contributed a baked model of the lunar surface, complete with coconut regolith and a basalt-tapping, meteorite impact and the breccia that filled its crater.

Anne Jefferson also pointed out that Maria Brumm from the now (sadly) inactive Green Gabbro had somewhat addressed this “sweet stuff shows geology” theme back in 2008:

Igneous petrology of ice cream (and an example that makes “xenoliths”)
Metamorphic petrology of ice cream

Sedimentary geology of ice cream

Lockwood of Outside the Interzone also dug into the archives with this post from last June, combining a series of fantasy cake images (for Nissan cars, of all things) with some actual photos of a “zebra” cake with gneissic banding. Lockwood was also kind enough to point to the Friends of the Pleistocene geo-art blog, which explored some of the connections between food and geology in a recent post called “Food for Thinkers”.

Lockwood was Mr. Link-tastic with this edition of the Wedge, pointing to all sorts of relevant posts, but he also delved into a really neat experiment on how to convert your own breath into calcite, an exercise which prompts reflections on the cycling of carbon through biological and geological reservoirs. Go check it out (bonus: you get to see what calcium looks like in its elemental state!)

Jessica Ball of Magma Cum Laude decided that she wanted to bake something relevant to her own volcanologic research, and so she made up a batch of rheomorphic tuff. As with the real-life inspiration, her cake has layers of mafic and felsic minerals that make a very impressive outcrop pattern:

An illustrated hypotheti-cake inspired me to bake something real that illustrated geologic principles. It led me to create a concoction that I dubbed “Baker’s Quarry,” and I explored its fake geology, and the story behind the real cake in a couple of posts.

For Chris Rowan of Highly Allochthonous, it was also all about the cross-section and the story it implied. Taking on the most famous unconformity outcrop in the world, the Siccar Point outcrop discovered by James Hutton, Chris baked a cake to match, and explained how it came to be that way.

Garry Hayes, a.k.a. Geotripper, brought forth a double-header – he started off with a block diagram of subduction rendered in icing, and then finished it off with a tray full of trilobite cookies.

If you like eating trilobite cookies, then other paleontologically-themed confections might appeal, like this Aardonyx cake from Adam Yates of the blog Dracovenator.

(Thanks to David Orr (@anatotitan) for alerting me to this via Twitter.)

There’s even a dinosaur “extinction hypotheses” cake, which is featured in this YouTube video:

Cian Dawson of Point Source also baked a cake that featured dinosaurs on top, but those beasts were but surface phenomena. Cian was interested in going down beneath them to examine the hydrology below the surface. His post on a “hydrogeologically correct cake” gives all the details.

Ann of Ann’s Musings on Geology and Other Things has a cake which reminded me of paleotology: it’s got a fossil baby in it! Called “King Cakes,” these macabre pastries are apparently a New Orleans tradition. Mmm, after all these fine desserts, I was feeling a bit stuffed, but if there’s one thing that could motivate me to dive into yet another cake, it’s the prospect of finding a plastic child inside it:

Curiously, the “King cake” tradition is motivated not by physical anthropology, but by religion. Check out Ann’s post to learn more.

To wash down all this cake, you might appreciate a cup of coffee. How about a cup of coffee that’s been sitting on the counter for two weeks? Silver Fox finds one in just that situation, and she deduced its age from counting the strandlines it left on the inside of her mug! Check it out at Looking for Detachment – very cool application of geological thinking to an everyday phenomenon.

And one more: Elli of Life In Plane Light suggests baked a cake with the intention to make a “schist” analogue, but it actually works better as an analogy for crystal settling. Check it out: all the chocolate chips sunk to the bottom of the batter “magma chamber” —

Check it out at her blog. While you’re at it, check out her use of corn syrup as an analogue for lava viscosity.

Thanks to everyone for their delectable contributions. Depending on how you count (intentional baking projects vs. links that just fit the theme) we had something like 21 individuals contributing to the 30th edition of the Accretionary Wedge.

Next 3 Accretionary Wedge topics & due dates

January 10, 2011

Bake Sale, Jan 28, 2011
Surprising new concepts, Feb 18, 2011
Parade of blogs, March 4, 2011