Geological terminology I hate.

Geological terminology is always evolving. The meanings of old terms can change through time. Early suggested terms may turn out to be inaccurate and may be replaced, or may become more or less specific in their usage. Nevertheless, old habits die hard. Certainly the use of certain terms help us establish or test identity or affinities - scientific jargon at large plays important roles in social relationships.

4. Basement
"Basement" is the ultimate relativistic term. It describes the rocks one is not interested in talking about. If you write a paper about soils, the recent sediments underneath may be the "basement". If you're writing about those sediments, the granite underneath those may be the basement. Basically it means whatever is older or under or around or near the rocks one is actually interested in. My friend Mike, who loves ice and lichen and moss and squirrels and everything else more than he loves rocks, gave me another variation on "basement" the other day when I accidentally picked him up on the Golden Gate Bridge: "underburden". Nice.

3. Subduction channel
Apologies to my good friend Åke, but this one has to die. The "subduction channel" refers to the area between the subducting lithosphere and the overriding plate in a subduction plate boundary, where sediments are subducted and variably deformed and metamorphosed and de-watered. It is generally seen as a tabular region - not linear - so it isn't the shape of a channel. The term also causes confusion due to some people suggesting models where material flows only downward through this "channel", while others invoke backflow within the "channel" to help uplift metamorphic rocks which record very deep conditions. Both camps use the term "channel" and neither one is describing a 1D feature. I'm just confused by this. Finally, in a channel, the flowing media flows in one direction relative to the walls of the channel, right? But in a "subduction channel" the flowing stuff (subducting sediments) moves in a direction and rate intermediate between the upper and lower walls. It's a shear zone. Not a channel.

2. Pseudotachylyte (or pseudotachylite)
Aside from having two spellings (-yte is older and therefore preferred although it is counter-intuitive most of the time and looks weird with 2 "y"'s so close to each other), the term "pseudotachylyte" is an example of defining something by what it is not, instead of what it is. Pseudotachylyte is a glassy rock formed by either seismic or impact-related melting of any rock (but in practice is restricted to silicates). It does not therefore include a whole suite of other glassy rocks (igneous, melt cortices on meteorites, etc), so it is not a good descriptive term, but requires an interpretation of how the thing formed. Finally, tachylyte is an igneous glassy rock similar to obsidian. So pseudotachylyte is something that could be mistaken for tachylyte but is not. Oh yah, and there are other very fine grained, dark coloured fault rocks (e.g. ultramylonite, ultracataclasite) that can't be distinguished from pseudotachylyte without some serious microscopy. So it's not useful as a field term either. Fail.

1. Pan-African
As far as I can devise from the literature, the term Pan-African refers to nearly any geological event (mostly magmatic but also metamorphic, deformational, etc) occurring during a period of approximately 250 million years (roughly 750-500Ma) anywhere in Africa or continents formerly associated with Africa. My dear colleagues who advocate the use of this term tell me the exact meaning can be deduced from the context of the specific location or events being discussed which makes this term actually less useful than not using any term at all. I can think of no good reason to use "Pan-African" at all unless one is trying to obscure the problem of massive dating errors or giant uncertainty about tectonic events. THIS ACTUALLY HAPPENS.

ok just to make me sound a little less cranky, here's a comment left by somebody called NJ on Kim's blog a while ago that makes me totally happy:

"You'd better wait. My desk is totally Franciscan right now and I have no idea where to start looking.

Or:

"He completely Franciscaned his first draft and his advisor wouldn't even read it."

Hollister - the Creeping Calaveras Fault

Every region has its particular strengths and weaknesses with regards to the type of geology which is easily accessible for student field trips. In the areas surrounding UCT, we have some seriously awesome geology but there are at least two things my students have to accept without seeing any really clear direct evidence in the field:

1. plates really move
2. plates really subduct.

Since I have a student from UCT with me in San Francisco this week for the AGU meeting (who gave a badass poster presentation by the way), it's a good opportunity to fill some of these gaps. We took an afternoon drive down to Hollister and San Juan Bautista to see some evidence for recent fault creep offsetting sidewalks and walls.

Hollister is positioned just north of the split where the Calaveras Fault branches from the main strand of the San Andreas Fault. The Calaveras Fault is creeping through Hollister, but rates vary along the fault in space and time from 3-18mm/yr (http://funnel.sfsu.edu/creep/SiteTable.htm).
(Map from http://quake.usgs.gov/recenteqs/)


My student is clearly excited by this right-lateral bulge in a garage wall.



Tension gashes where the fault crosses the street at a high angle and disappears straight under the middle of a house.
wonky sidewalk
another wonky sidewalk
seriously wonky sidewalk, and the steep small hill on the left of the photo is a pressure ridge
wonky sidewalk
more tension gashes in the street
carly will be creeping to your right as you look at this photo.

It's cool to see how different sidewalks and houses of different ages have accumulated different amounts of offset. We also couldn't help noticing new skirting and lots of concrete repairs which presumably addressed the larger offsets. Also - in some places the total offset was accommodated by narrow strands (usually ~ 1m wide) but in others, the deforming zone seemed to be much wider (10m). Seems like this depends on local soil conditions as well as the rigidity of the surface features. Sometimes it is wide under a sidewalk and sometimes all the strain seems to accumulate on one joint between sidewalk panels, as in the last photo.

Today we are off to Ring Mountain with Åke to see some evidence for #2.

The Cake Practical

The theme of this month's Accretionary Wedge blog carnival is "Time to Think Out of the Box", in terms of approaches to teaching. I thought I'd contribute an activity I've been running in my classes which comes directly out of a box - a cake mix box.

We spend a lot of time in my Honours tectonics class (that's equivalent to a senior seminar in Tectonics in the states) talking about the lithosphere.

We discuss and in some cases, calculate:

• the flexural thickness (relatively thin, <10km>
• thermal definitions (thickness varies, but temperature is really a proxy for rheology),
  
• definitions based on a sheared layer (high seismic anisotropy) separating the lithosphere from the asthenosphere,
  
• more abstract definitions based on calculated rheologic transitions (using more complex proxies than just temperature)
  
• discussion expanded this year to include looking at sub-continental lithospheric mantle which has been a stable geochemical reservoir for a very long time.. therefore not likely communicating with the convecting mantle (shout out to my colleague Steve), a distinction which is obviously important and in some places observable but was previously not on my radar.

However, for the students to really grok* this they have to have a good grasp on the concept that the same material can behave both as either an elastic or ductile solid under different conditions of pressure and temperature. There begins the search for an analog material.

The Cake Practical

As it turns out, cake deforms elastically at low stress and non-recoverably (let's call it viscous) at higher stress. This is a cheap tolerable proxy for Maxwell behavior. I bake some thin sheet cakes - from an ordinary cake mix - each pair of students gets about 100cm² piece of 3cm thick cake. The technical staff of the department was kind enough to provide me with a few "core samplers" = pieces of 1" pvc, about 2" long, with a nice bevel cut around one end to sharpen it for cutting into the cake. They also need an ordinary metric ruler and a watch or cell phone with a stopwatch.

The students cut as many sample cores from the cake as they can. This leads to a bit of waste, invariably eaten, thereby increasing the general level of blood sugar excitement in the room.

Fernando shows his glee at performing rheological experiments
on rock analog materials. Photo: William Cheng.

I give a bit of a talk about elastic at low stress, viscous at higher stress rheologic models and remind them that elastic deformation is linearly related to stress by the Young's modulus:

σ = E * e
where σ is stress in Pascals, E is the Young's Modulus in Pascals, and e is the linear strain (change in length / original length).

They are also reminded that viscosity is the relationship between stress and strain rate, not linear strain, by the relation:

σ = η * ε

Where η is the viscosity in Pa*s and ε is the strain rate in s^-1.

We assume a Maxwell rheology wherein:

σ = η ε + E e

and also assume that if we do experiments at very low stress, viscous strain negligible (all strain is elastic) and therefore set η ε = 0 at very low stress. This enables the students to isolate the Young's modulus (E).

Load is applied by placing other food items (of labeled mass, e.g. small cans and jars) on top of the cake cores. The students measure the surface area of contact and calculate applied stress.**

The students are asked to design and execute experiments to determine:

• the Young's Modulus

Cake sample after elastic rebound (there's a bit of a delay there - hysteresis loop?)
Photo: William Cheng

This turns out to be amazingly reproducible. For my cake this year, everybody seemed to get a result between 5-8 kPa. Or, since the concept of significant figures doesn't seem to have taken hold, 6449.33352 Pa.... that's another issue.

• the elastic limit

100g jar of capers produces about 1.2 kPa load on the cake core.
Amazingly, at 50% shortening the cake core still rebounds elastically.
Must be all those eggs I put in.
Photo: William Cheng

This parameter is bracketed by increasing the load on the sample until the sample no longer rebounds elastically to its original height after the load is removed. For the cans and jars I brought, all groups bounded the elastic limit at between 100g capers and 400g organic kidney beans. With our cake core samples this is between about 1-6 kPa. Next time I would get more intermediate weights.

• the viscosity (for deformation above the elastic limit)
  

Under the 400g can o' beans, the cake has gone viscous and very little rebound is
observed. No conch shell or painted stick reported either...
(Photo: William Cheng)

The viscosity is the most unreliable part of this experiment, mostly because the students have to estimate the timescale of deformation and that timescale is very short. Perhaps larger pieces of cake would address this....

Anyway this prac gets good reviews. The discussions of the lithosphere seem to go well afterwards, although I will let you know for sure after the exams in October. I have used the same concept for a more open-ended inquiry and had students investigating the shear modulus by sheathing the cores in plastic wrap and shearing them, investigating the temperature effects by freezing them and microwaving them [don't tell the boss I broke into his lab for a little N₂ (liq)]. Obviously no amount of temperature increase is going to allow dislocation glide in chocolate so the metaphor rapidly breaks down. However - I never have to clean anything up with this lab... except wiping a few crumbs from the table tops.

Hoping someone out there will improve on this or suggest improvements... leave me a comment if you have any ideas!

*I was introduced to the Grok concept by my algebra II teacher in high school who made us chant (daily) the quadratic formula "so that if any of you two reproduce, your children will be born knowing it". Well, Mr. Steiger, x equals the opposite of B plus or minus the square root of B squared minus four-A-C over two-A.

** Yes I'm aware that the labeled weight on the can only refers to the food inside and does not include the weight of the container. Trust me this is not the largest source of error here and anyway, saves time and hassle when the students have only a short time to complete their experiments.

Some advice if you are looking for a grad school program

Greetings all. As the application season is coming around soon, I've been getting a lot of questions lately about how to find the right graduate school or project. So here are some comments about the criteria I think are important... and how to go about looking for the right match. This is by no means a comprehensive set of instructions, more like an incomplete list of FAQ...

APPROPRIATE PROJECT
You best find something that turns you on right from the beginning. You're probably going to hate it at some point, sooner or later, and you'll need some serious motivation to help you get through the low spots. You should be interested in both the BIG QUESTIONS and the PIDDLING DETAILS of your project.

The project ought to be the right scale for the degree you are seeking (MS or PhD) or have the potential to scale up or down if needed. It ought to afford you the opportunity to learn some specific skills or get experience which will make nice bullets on your CV.

THE RIGHT GROUP FOR THE PROJECT AND FOR YOU
The adviser, and members of the research group, should be experts in the background of your intended research projects. Someone should have those specific skills that you intend to learn. It is common for a student project to require a skill which is not currently in the group repertoire - something the student can learn and then contribute to the group. This depends on the past experience of the student.

Adviser personal skills and attitude toward advising can affect the quality of life for a newby grad student to a great extent - take a look at the rest of the group and ask current students privately about the group dynamics. However, keep in mind that graduate students are nearly always disgruntled. It's a point of pride. After a campus visit or two, you will easily pick out happy/functional groups and... other groups. There are sometimes sad mismatches of adviser and student style/personality. Learning about the group dynamics can help you avoid these.

Think about how you enjoy spending long hours. If you are fascinated by the outer core, but hate math, you may be out of luck because most people who study the inner core are seismologists and modelers. Even if you don't know exactly what topic you want to study, but have an idea of what you enjoy/are good at, you will have a better chance of finding the right project for you.

STARTING THE SEARCH
Use a search engine to find journal articles that interest you. Google the authors. Nearly everybody teaching at a university has a website that includes a summary of their research, publication list, and past student projects. I googled about 50 people and narrowed down 12 to email directly. I have no idea if these are typical numbers. Ask your professors for advice. If you are able to, go to conferences! GSA and AGU are great places to shop programs/advisors/projects and distribute your CV. Watch the ads in EOS and GSAToday

When emailing potential advisors:

Learn what you can about the advisor/group and write a personalized email showing that you have done your homework. I immediately delete emails of inquiry which make clear that the student has not looked at my webpage and is not interested in anything I do. Ironically, anything that says "Dear Sir" will get a response - A strongly worded response.

Keep it short. One paragraph is plenty. Be focused and organized. Include a sentence or two summarizing your background and offer a CV on request or a link to your CV download (do not attach it to the first email as you might end up in the spam folder, and it's presumptuous). Clearly state why you are interested in this particular person's research. If your interests are broad, you may write to more than one member of a department. It is expected that you are shopping around.

Don't kiss ass. Don't alter your email so strongly for different targets that you look like you're kissing ass or being fake - people do talk, especially people in related fields. Keep your CV short (1 page is usually plenty) and if you have job experience which is not related to your application, just summarize it briefly (e.g. no list of babysitting references here!)

Edited to add: read FSP's post before you send that email!

FINDING FUNDING

In the USA - finding funding is usually a joint effort between advisor and student.

Students typically support their education by some combination of grants, teaching assistantships, research assistantships, and loans.

Grants/Fellowships: can come from the Univ, Advisors' grants, or any number of private institutions. Potential advisors will have knowledge of appropriate opportunities in your field. These could be for direct support (living, tuition) and/or research expenses.

-- NSF Graduate Research Fellowship. This money follows the student even if they switch universities, advisors, projects for 3 years. quite competitive and lucrative. Obama just tripled the number of Fellowships!!! applications open in August 2009.

Most of the advisors' grant money comes directly or indirectly from the National Science Foundation, or in some fields, DOE or other agencies. Many of these grants are written with some student support in the form of TA or RA positions. Expect to be asked to work ~20hrs/wk and receive adequate compensation for tuition, health insurance, and a small living allowance. FYI that 20hrs is a completely made up number and has almost nothing to do with your workload in practice.... (see above reference to graduate student disgruntlement).

In South Africa...
If you are South African, you can apply for an NRF bursary. This is something like R35 000/yr for MSc students and R60 000/yr for PhD. Not enough to get by in Cape Town but maybe in some other cities it's enough? I'm not sure. Many students get support from an employer and nearly everyone supplements that with demonstrating (TA) jobs. There are other pools of money available specifically for scarce skills development (including geology) and for previously disadvantaged populations (everybody but white males who had citizenship or permanent residency before 1994, varies whether white females are still considered disadvantaged. But that's another topic for another post.)

In any case, your supervisor will have more insight on funding opportunities and again, it should be a joint effort between student and supervisor to get the money together.

AND NOW SOME UNSOLICITED ADVICE...
Don't be afraid to apply overseas for your graduate studies. It's a great stage of life to try out living in a foreign country, as your life is relatively institutionalized so it's not as lonesome as moving somewhere entirely on your own. There are additional challenges - funding is often earmarked for citizens of that country, there are issues with translating transcripts and qualifications... but it's an excellent chance to spend a few years building relationships/support networks in the international community. In particular, for South African students it's a chance to get a world view in your field in a short period of time, during which somebody (your supervisor) is officially committed to supporting you and your development as a scientist. You can bring those relationships back to your home country, but it's far more difficult to develop them without investing the time overseas. When so much research funding is available through international collaborations with Europe or the US, those connections can help support you through subsequent decades of your career.

Alright i'm off the soapbox... did I forget anything?

Winners

The Art of Subduction took 3rd place at the annual Geological Society of South Africa Western Cape Branch Quiz night.

Nice job team.

Fun with Folds

BrianR at Clastic Detritus posted a great photo of some disharmonic folds in bedded strata. Here are some more!


I particularly like the chocolate-tablet layers visible on the top of this outcrop.

Fully Equipped Field Geologist

Alright I'm a bit behind the curve here... but ever since The Lost Geologist posted a photo showing all the bells and whistles comprising the field geologist's kit, the world of geobloggers has been weighing in. (Also see... Geotripper, Hypocentre, Kim, the Ethical Palaeontologist, Johannes, Silver Fox, etc...)

Over the years I've developed some very climate and duration specific field kits. I hate to carry anything I don't need and I hate to be overloaded as to be uncomfortably hot. I also hate to run out of water and/or food.

Always have:
1. No Belt. I wear pants or shorts with many deep pockets. In those: Brunton Compass (I have one for S and one for N-hemisphere field work) Rite-In-The-Rain field book, at least 2 mechanical pencils, fatty eraser, many fine-tipped sharpies in multiple colours, a few big black sharpies for marking samples. Can't have enough sharpies. (often: cell phone, gps, whistle)

2. Handlens(s) on a chord around my neck.

3. At least twice the water I think I will need. Two or more pieces of fruit which are waste-free (I eat apple cores and orange peels rather than leave them in the field or carry them home. Thanks to Eric Thompson for long ago convincing me of the edibility of citrus peels). To keep this light as possible, I have knit some water bottle slings which I will use in place of carrying a pack if the water is all I'm bringing.

4. Map board - still using the Hilde Schwartz-style boards from UC Santa Cruz which are made from two pieces of plexiglass (one with a 1.5" bit cut off from one side), duct tape, and binder clips. Put the topo maps +/- aerial photos in here. I'm still looking for a replacement for standard binder clips which does not affect my compass, as I do end up taking measurements on the map board pretty often.

5. Peanut butter and jelly sandwiches in zip-lock baggies (also twice as many as I think I could possibly need; these roll over every day if I don't eat them. They keep just fine, even improve with age(?), they're high energy, and there's no need to wash out the ziplock between pb&js.

6. Camera. Currently rocking the Canon EOS 1000D. Always with spare battery and SD cards.

Hot Weather Kit: Photo by Taufeeq Dhansay, Near Monapo, Mozambique (2008)

----That's it for the "always" items. ---

7. Hammer and heavy plastic bags, duct tape, and super glue for sampling - The way I do field work often involves several days of structural measurements at one outcrop or small area - normally then I do all the data collection and then set aside a day for sampling at the end. That way I don't a) smash anything I should have measured or b) take unneccessary samples before I understand the full picture. This has been a pretty important adaptation to my field plan because as a structural geologist who works on brittle rocks I NEED REALLY BIG ROCK SAMPLES and when rocks cross borders in Africa, they often have to go through customs with a certified currier company. This means I pay by the kilo. I want fewer, bigger, better samples.

----Matters of personal style---

When mapping in arid and semi-arid environments, I wear running shoes ("takkies") with short cotton socks. I hate being too hot more than I hate getting my legs all scratched up in the blasted fynbos. I wear SPF40 super waterproof sunscreen everywhere but somehow end up burned anyway.

When mapping in cold wet places, I wear NO COTTON WHATSOEVER not even underwear. Synthetics and wool only. In Alaska I often wear extra-tuffs while mapping in the field but I'm not sure this is the best way to go.

Hair: Always with the dual-braid configuration. Fits best under hats.

Hat: My SeaHawk Air hat has been my standard since 02. However, I lost it when it blew away in sub-gail force winds while I was sitting on top of a really fantastic sycline-axis koppie with a crinkly little bit of Prince Albert Formation in a sea of Dwyka diamictites. I got SeaHawk to send me another and it's almost as good. Finally, Sila talked me into getting a proper 360-degree brimmed floppy hat and it's ... alright. But I feel like such a dork.

Pants: Dork score increasing here: I wear zip-offs these days. Specifically, Convertable nylon pants from Cape Storm. They have kick-ass pockets with zippers so i don't lose keys. They look terrible because there is some bunchy elastic at the back for some odd reason. I don't care. They are light-weight and seemingly bulletproof, even in the face of elephant-skin weathering (also known as tareponts weathering to the Poleta crew).

Kit for Alaska field work: Photo: Asuka Yamaguchi, June 2006



---- Also, things that live in my backpack forever ---
knife
15m of good strong 3mm nylon line (good for clothesline if nothing else)
a powerbar or two of unknown antiquity
ziplock baggie of extra TP (also of unknown antiquity)


Ha ha I'm looking for pictures of myself in the field and I realize something that's present in nearly every photo but I completely forgot to add to the list:


Students. Not technically required for every field campaign but they sure do make it more fun. That's me in the green. Laingsburg field trip 2008. (not sure who took this picture.)

Coincidence:

Richard Firestone will be giving a talk on Tuesday at the Peninsula Geological Society meeting at Stanford on evidence for supernova-related impact events correlated to Cenozoic climate events and extinctions. And that's his real name! Or so I assume...

My dad will be there to ask him some insano questions afterwards, like, "how do your results affect the aquatic ape hypothesis?" Other than that, I'm sorry to miss it. Details here.

Geology is boring - Punk kid.

DATELINE: Yesterday on the beach in front of Ons Huisie, Klein Baai, Cape Town:

Punk Eight-year old Kid: Hey what are you looking for in the rocks?

Me: We're geologists so we study rocks.

PEYOK: That must be boring.

Me: It might sound that way at first but the more you learn about it, the more interesting it gets.

PEYOK: Hm.

Me: The whole history of South Africa and how it got here is hidden in these rocks.

PEYOK: Whatever. (runs away)

New Year's Geolutions

I have been in South Africa for 2+ years now and seen very few of the BIG SOUTH AFRICAN THINGS I meant to see. So I'm suggesting a new meme for you geobloggers out there to follow up on Geotripper's list of the 100 things we all "ought" to see.

What are 10 things you have never seen before, which you hope or plan to see in 2009?

Here are my ten GEOLUTIONS for 2009:
1. Wolfberg Cracks/ Wolfberg Arch Cederberg Mountains, South Africa
2. Etosha Pan, Namibia
3. Any really big wall of San Bushman Paintings
4. Coarse Kyanite schist in the Monapo Complex, Mozambique
5. The Vredefort Crater with the mega-pseudotachylyte breccias, shatter cones, the works.
6. Jeffrey's Bay aka JBay, the world-famous SA surf spot
7. Gems in Sri Lanka
8. Forest elephants in Addo National Park
9. The Bushveld Layered Igneous Intrusion
10. Triassic therapids in the Beaufort Formation, Karoo Basin...

Also for good measure (and a spin), 5 things I want to find or see evidence for (or against, as it may come). These are research goals, or ideas, as well as hobbies, or wishes for my students, etc...:

1. Incipient westward propagation of the Okavango Rift across the Botswana-Namibia border
2. Fluidized granular flow of very thick (meter or more) gouge layers in shallow crustal faults
3. Tectonic environment of the deformation of the "Saldanian belt"
4. Syn-crystallization shearing of the pegmatitic ijolites of the Mazeripane Suite, Mozambique
5. Tectonic fabrics in the Cape Granite Suite - timing, spacing and source.

Finally, how about 10 things that should be on the top 100 List? I totally concur with Geotripper's reticence to rewrite the list himself, as it is politically sticky and never unbiased. But for the sake of it, what would you add?

1. A famous "big wave" e.g. Maverics or Dungeons, breaking.
2. A glacier calving into the sea
3. Pink sand beaches (e.g. Bahamas)
4. Singing beaches or dunes
5. Walk across and observe a metamorphic aureole
6. Experience an earthquake
7. See the snowball earth stratal assemblage (e.g. diamictites+carbonates)
8. An earthquake damaged area, e.g. Earthquake Park in Anchorage
9. A Bore tide
10.Hear the sound of waves in a fjord.

I wonder why we geologists emphasize the fast/rare things on this list, instead of the slow/common things... which are more truly special to observe...

Apologies for missing the geobloggers dinner on Weds, I was too jetlagged/overwhelmed to stay so I went and worked on my talk in bed.

11. Hoping i get another chance to meet Kim Hannula

New Lows Achieved.

Two things I said I would not do: join facebook; do a blog meme. Today I did both. Anybody want to come over and give me a tattoo or a makeover or something? Just so I can become totally unrecognizable to myself.

This one is pretty fun. Geotripper is responsible for this. Following Chris Rowan's lead, I'll post a photo where possible. Bold ones are CHECKED OFF. Italicized are checked off sensu lato.

1. See an erupting volcano
(erupting what? if steam and gas, YES (Yellowstone). if magma, NO.)
2. See a glacier (unID'd glacier near Whittier, Alaska)

3. See an active geyser such as those in Yellowstone, New Zealand or the type locality of Iceland
4. Visit the Cretaceous/Tertiary (KT) Boundary. Possible locations include Gubbio, Italy, Stevns Klint, Denmark, the Red Deer River Valley near Drumheller, Alberta.
(according to my field books, I saw it in the Elk River Basin, WY. However, I don't recall this.)
5. Observe (from a safe distance) a river whose discharge is above bankful stage
6. Explore a limestone cave. Try Carlsbad Caverns in New Mexico, Lehman Caves in Great Basin National Park, or the caves of Kentucky or TAG (Tennessee, Alabama, and Georgia)
7. Tour an open pit mine, such as those in Butte, Montana, Bingham Canyon, Utah, Summitville, Colorado, Globe or Morenci, Arizona, or Chuquicamata, Chile.
8. Explore a subsurface mine.
9. See an ophiolite, such as the ophiolite complex in Oman or the Troodos complex on the Island Cyprus (if on a budget, try the Coast Ranges or Klamath Mountains of California).
10. An anorthosite complex, such as those in Labrador, the Adirondacks, and Niger (there's some anorthosite in southern California too).
11. A slot canyon. Many of these amazing canyons are less than 3 feet wide and over 100 feet deep. They reside on the Colorado Plateau. Among the best are Antelope Canyon, Brimstone Canyon, Spooky Gulch and the Round Valley Draw.
12. Varves, whether you see the type section in Sweden or examples elsewhere.
(Smith College - Paradise Pond!)
13. An exfoliation dome, such as those in the Sierra Nevada.
14. A layered igneous intrusion, such as the Stillwater complex in Montana or the Skaergaard Complex in Eastern Greenland.
15. Coastlines along the leading and trailing edge of a tectonic plate
16. A gingko tree. (Smith College again!)
17. Living and fossilized stromatolites (Glacier National Park is a great place to see fossil stromatolites, while Shark Bay in Australia is the place to see living ones)
18. A field of glacial erratics Smith college rugby field! also freshies in Alaska and fossil in South Africa
19. A caldera Long Valley! Yellowstone! Haleakela!
20. A sand dune more than 200 feet high Namib Desert, Sossusvlei
21. A fjord (unknown fjords in Kenai Mts, Alaska; photo by my colleague francesca)

22. A recently formed fault scarp Lone Pine, CA
23. A megabreccia Death Valley
24. An actively accreting river delta
25. A natural bridge Natural Bridges Beach, santa cruz!
26. A large sinkhole
27. A glacial outwash plain Alaska
28. A sea stack
29. A house-sized glacial erratic
30. An underground lake or river
31. The continental divide
32. Fluorescent and phosphorescent minerals
33. Petrified trees fossil ridge Y-stone, also in Anza Borrego but just pieces
34. Lava tubes Bend, OR and hilo
35. The Grand Canyon. All the way down. And back.
36. Meteor Crater, Arizona, also known as the Barringer Crater, to see an impact crater on a scale that is comprehensible
37. The Great Barrier Reef, northeastern Australia, to see the largest coral reef in the world.
38. The Bay of Fundy, New Brunswick and Nova Scotia, Canada, to see the highest tides in the world (up to 16m)
39. The Waterpocket Fold, Utah, to see well exposed folds on a massive scale. I think the Cape Fold Belt qualifies for this one:

40. The Banded Iron Formation, Michigan, to better appreciate the air you breathe.
41. The Snows of Kilimanjaro, Tanzania,
42. Lake Baikal, Siberia, to see the deepest lake in the world (1,620 m) with 20 percent of the Earth's fresh water.
43. Ayers Rock (known now by the Aboriginal name of Uluru), Australia. This inselberg of nearly vertical Precambrian strata is about 2.5 kilometers long and more than 350 meters high
44. Devil's Tower, northeastern Wyoming, to see a classic example of columnar jointing
45. The Alps.
46. Telescope Peak, in Death Valley National Park. From this spectacular summit you can look down onto the floor of Death Valley - 11,330 feet below.
47. The Li River, China, to see the fantastic tower karst that appears in much Chinese art
48. The Dalmation Coast of Croatia, to see the original Karst.
49. The Gorge of Bhagirathi, one of the sacred headwaters of the Ganges, in the Indian Himalayas, where the river flows from an ice tunnel beneath the Gangatori Glacier into a deep gorge.
50. The Goosenecks of the San Juan River, Utah, an impressive series of entrenched meanders.
51. Shiprock, New Mexico, to see a large volcanic neck
52. Land's End, Cornwall, Great Britain, for fractured granites that have feldspar crystals bigger than your fist.
53. Tierra del Fuego, Chile and Argentina, to see the Straights of Magellan and the southernmost tip of South America.
54. Mount St. Helens, Washington, to see the results of recent explosive volcanism.
55. The Giant's Causeway and the Antrim Plateau, Northern Ireland, to see polygonally fractured basaltic flows.
56. The Great Rift Valley in Africa.
57. The Matterhorn, along the Swiss/Italian border, to see the classic "horn".
58. The Carolina Bays, along the Carolinian and Georgian coastal plain
59. The Mima Mounds near Olympia, Washington
60. Siccar Point, Berwickshire, Scotland, where James Hutton (the "father" of modern geology) observed the classic unconformity
61. The moving rocks of Racetrack Playa in Death Valley
62. Yosemite Valley
63. Landscape Arch (or Delicate Arch) in Utah
64. The Burgess Shale in British Columbia
65. The Channeled Scablands of central Washington
66. Bryce Canyon
67. Grand Prismatic Spring at Yellowstone
68. Monument Valley
69. The San Andreas fault
70. The dinosaur footprints in La Rioja, Spain
71. The volcanic landscapes of the Canary Islands
72. The Pyrennees Mountains
73. The Lime Caves at Karamea on the West Coast of New Zealand
74. Denali (an orogeny in progress)
75. A catastrophic mass wasting event
76. The giant crossbeds visible at Zion National Park
77. The black sand beaches in Hawaii (or the green sand-olivine beaches)
78. Barton Springs in Texas
79. Hells Canyon in Idaho
80. The Black Canyon of the Gunnison in Colorado
81. The Tunguska Impact site in Siberia
82. Feel an earthquake with a magnitude greater than 5.0. Loma Prieta!
83. Find dinosaur footprints in situ Dinosaur Tracks, MA
84. Find a trilobite (or a dinosaur bone or any other fossil)
85. Find gold, however small the flake
86. Find a meteorite fragment
87. Experience a volcanic ashfall
88. Experience a sandstorm
89. See a tsunami
90. Witness a total solar eclipse
91. Witness a tornado firsthand.
92. Witness a meteor storm, a term used to describe a particularly intense (1000+ per minute) meteor shower
93. View Saturn and its moons through a respectable telescope.
94. See the Aurora borealis, otherwise known as the northern lights.
95. View a great naked-eye comet, an opportunity which occurs only a few times per century
96. See a lunar eclipse
97. View a distant galaxy through a large telescope
98. Experience a hurricane
99. See noctilucent clouds
100. See the green flash

Score: 42 sensu stricto
ps. I did post a bunch of rock pictures on facebook though.

Dwykacious Injectites

The famous Dwyka "Tillites". As previously ranted on this blog, these are not lithified tills! They are glaciomarine. As proof, I offer the drop pebble. Isn't he cute. (top of photo is stratigraphic top)

The Dwyka Group contains one formation, the Elandsvlei Fm., making it the city and county of San Francisco of geologic Groups. Sorry if that's too corny for you. The whole package is matrix-supported, laminated and massive diamictites. The massive ones are ridge-formers in the field area and the laminated ones are valley-formers. They are informal called "coarse" for the ridge formers and "fine" for the valley formers but I actually think the difference is in cementation rather than grain size, possibly having to do with more abundant clays in the "fine" laminated units prohibiting silica circulation. The matrix is glacial rock flour, a very fine sediment (quartz/felspar ground down to clay-size particles) which is unique to glacial erosion.

Anyways, along some of these facies-boundaries we have channel sands. These are often called "eskers" but they are not true eskers as this is not a ground moraine.
Super TA Nic perched on the stratigraphic top of one of these channel sands - the dip is to the left on the photo at about 40*S and Nic is sitting on the top of the deepest part of the channel. Original vertical thickness is about 2m and the sand body tapers to the foreground and background (these represent the edges of the channel). This particular channel deposit has a nice coarse, well-rounded conglomerate around the edges - like a gravel bar? The matrix of the conglomerate is greenish-gray rock flour, resembling the rock into which the channel cut.

Here's where things get even better (and by "better" I mean "more structurally interesting"). See that long spindly (~15cm thick) sandy arm reaching gently UPSECTION from the sandstone channel? IT'S A SANDSTONE INJECTITE! If you look carefully at the photo (click to enlarge if you need to) you will see that the lamination in the gray-green matrix is going roughly across the photo while the dyke cuts upsection (and up-photo) to the left.

Injectites usually form when a porous, saturated sediment is overlain by a less porous sediment. The overlying rock acts as a seal and doesn't allow the water to escape from the porous sediment. Pressure increases as the sediments are buried and eventually the porous rock can become very "overpressured", with the trapped water in the pores carrying the weight of the rocks above. This is an unstable state and can only persist as long as the overlying seal rock can withstand the pressure! Eventually, the sealing rock fails - usually along a planar or curviplanar fracture - this occurs when the overpressure reaches a greater magnitude than the weight of the rock, or some kind of disturbance (earthquake, passing landslide or debris flow) triggers the failure. The high pressure fluid/sediment mixture escapes its former captivity by injecting outward and upward along the fractures. When the pressure is released, the water is free to move off but the sediment is left behind in the fractures, forming "injectites" or "sandstone dykes".

The injectites are found in a particular stratigraphic horizon in the Dwyka Group (2c/3f contact for those of you in the know) where small sandy bodies are common. The sand is coarse, well-sorted and nearly pure quartz (C. Herbert pers. comm. last week in the computer lab). Injectites are curviplanar with roughly parallel surfaces (although they sometimes undulate out of phase). Thickness varies from about 25cm to 3cm in the several examples Nic and I stumbled upon while looking for faults fortuitously discovered. The outer surfaces of the injectites are very smooth and polished. They are now quartz cemented and weather out relative to the finer-grained, less well-cemented rock flour matrix.


The outer wall surfaces of the injectites have a very distinctive texture - I don't know if it has a name, but it's something like flute marks but sort of braided looking.... Can anyone help me out here? Has this been described before? Perhaps my dear friend the "former" geologist can help.

Have I ever told you that you can't un-geologist yourself? It's like finding out about santa claus carter. Your world has rocks in it and that makes you different... forever.

Eh hem, excuse me. Anyway, the anastomosing flutes are about a centimeter to 3cm in wavelength, with high amplitude (~0.5x wavelength) and vary quite a bit in length. Sources say that the famous Panoche Hills injectite complex in central California may show similar clastic-dike-margin-textures... but on a larger scale...



The geometries fo the injectites can be rather complex - they are even sorted with coarsening towards the center - reflecting increased flow velocities with distance from the conduit walls. Here's Nic again sitting on what is either a) a folded injectite or b) the complex branching/intersection of multiple injectites - Somebody should find out!
What can these surface textures tell us about viscosity and velocity of injectites, strength of sediments, and fluid pressure in the ancient sub-glacial-icey seas? Somebody should find out! Who should that somebody be? I'm hoping one of my future honours students....


In case you doubt that these sandstone channels are submarine, I present you... the drop-boulder. I'm sorry, so sorry for this but each time I look at this picture I think of Cornwallis.

Ptygmatic Folds in the Prince Albert Shales

The first exercise I do with the students when we begin working in Laingsburg is to have them run around just outside the field station and find a fold. Luckily this is not so hard as the Prince Albert Formation here is wrinkled like a raisin. I have some theories about this.

Sorry for the crap outcrop photo - should have taken the advice about
"morning vs. afternoon shots".

The Prince Albert Formation is early Permian in age and directly overlies the Dwyka Group diamictites dating from the Carboniferous-Permian Gondwanide glaciation. The paleo-latitude is about 70°S. I have a massive pet peeve about people calling the Dwyka Group "tillites" because that term clearly implies terrestrial origin and the rocks are very clearly submarine. The first person to describe the rocks (Alex du Toit in 1929) may not have known this but the very detailed work of JNJ Visser in the 70s and 80s made very clear the glacio-marine origin. If there's any doubt, please see: dropstones everywhere throughout the sequence. So don't say "Dwyka Tillite" to me unless you want to hear more about that. But I digress! I'll return to the Dwyka in future posts because I'm finding it more and more fun. Rock flour is weird.

Anyway, the Prince Albert Formation overlies the mudcracked glacial muds at the top of the Dwyka. It has a few meters of grayish pink shales/siltstones, followed by a few more meters of chestnut brown shales/siltstones, and then a few more meters yet of black shales/siltstones with blue phosphate nodules (and at least one 8-cm thick black chert bed, discovered by my students this year! Shout out to Klipdrift Group!). I'm being vague about thickness because nearly everywhere we see the Prince Albert in the Laingsburg area it is majorly folded and faulted and we actually have no clear idea how thick it should be. Looks like it was the preferential site for accomodating strain in the stratigraphic sequence. I would guess it is related to the big hard massive Dwyka diamictite below, and the relatively deformable Ecca Group turbidites above - those two strain very differently and the Prince Albert had to squish around to make up the difference. That would be the technical term of course. You see - this is how I check whether my students are plagiarising my blog.

Anyway, you can see in the photo above that some beds make nice concentric folds and others make parallel folds (see different shapes within the little syncline on the right). On this local scale, the thin yellowish ash beds flow into the hinges to accommodate the different shapes of adjacent folded beds. I think the Prince Albert Formation on a regional scale is doing the same thing the yellow ash beds are doing on this outcrop scale - flowing toward the hinges.

Maybe you need a refresher on folding mechanisms? Check this one out.

Do you see the amazing cleavage refraction?

Our class rep, also known as "the ginger kid" (in his own mind at least)
is impressed by the faulted folds.

The style of folds varies between the pinkish grey, chestnut and black members of the Prince Albert, I think as a function of viscosity variation in the strata. In the basal pinkish-grey member, there are lots of fine clayey shales and a few "siltstone" beds which are pretty hard and quartz cemented. This results in a thin stiff layer in a low viscosity matrix - the necessary condition for... (drum roll please)... PTYGMATIC FOLDS!

Mineralogy MacGyver

What do you do when you're out in the field and you really really wish you could positively identify a particular mineral? There are ways of doing this which are no longer taught - involving powders and torches and things like that - I never learned these methods, these days we just take the rock home and make a thin section.

We were in northern Mozambique looking at what appear to be charnockitized gneisses - which should by definition contain pyroxene - normally orthopyroxene. However, the thin sections we made last year just had clumpy biotite - maybe replacing opx? But without finding any remnant opx we couldn't be sure if it had ever been there, or if all the patchiness we could see in the rock was just clumpy biotite. We crushed up some of the gneisses, which wasn't too hard to do because they have a nice "sugary", recrystallized annealed texture and readily fall into angular "sand". Some of the grains had a greenish smokey luster - possible orthopyroxene? Or just ugly looking feldspars? Or quartz with some micro inclusions? If only we could see the birefringence of the mineral grains we could readily pick out the opx - which has higher birefringence - from the feldspar and quartz, which have similar, low birefringence.

Birefringence is the effect when light passes through a crystal more quickly in one direction than in another, effectively splitting light like a prism. The strength of this effect varies with the wavelength of light as well as with the properties of the crystal. The birefringence of different minerals is a characteristic feature that can be used to identify them. To see this effect, geologic microscopes use two polarizing filters. Full-spectrum light is passed through a polarizing filter and then through a thin section of rock (30-microns is the usual thickness for this slide). Then the light passes through a second, polarizing filter perpendicular to the first one and through to your eye.

Two polarizing filters at right angles to each other will block all light - so if there is no rock slide in the path of the light, or if there is just glass or some other isotropic material in the path of the light, you will see nothing at all. However, a birefringent rock sample will take the oriented light and twist it - allowing some of it to pass through the second filter. The colour you see will change depending on how strongly the mineral "twists" the rays of light.


So what to do in the field with no slide, no microscope, no way to estimate the birefringence of these mineral grains? Kosuke came up with an answer - like geologist MacGyver. He used the polarizing filters from his camera lenses - mounted them on an incandescent head lamp (torch) and put the mineral grains in between. He then carefully rotated the top filter so that it blocked out all light except for what was passing through the mineral grains. Voila! A field petrographic microscope!

Did it work? Sadly, not really. The problem was, of course, that all the mineral grains had different diameters and therefore the path of light through the minerals wasn't constant. As the colour you see is a function of the length of path as well as the properties of the crystal, we couldn't keep this factor constant and were left with uncertain results. However, it was a pretty good exercise (and a lot of fun) and a reminder of the basic principles of geology which we sometimes take for granted.

You know what? Identifying rocks is pretty hard. Very few minerals come in only one color or shape, and a little bit of weathering or deformation can change the appearance of a rock pretty drastically. Geologists and geology students have to learn a whole range of criteria which change from place to place and rock to rock. It's a lifetime effort to learn to identify rocks, accelerated by seeing as many rocks as one possibly can but one can never hope to see them all.

In accretionary wedges - my "specialty" (if I have one, that is) - low temperature metamorphism and high strain can result in all the rocks looking pretty much the same - it can be very difficult to tell an igneous rock (eg. basaltic ash from the ocean floor) from a sedimentary one (e.g. volcaniclastic greywacke). It's hard to tell students that the first basic thing we tell them about rocks - that there are 3 types (igneous, metamorphic and sedimentary) might be the last thing you figure out about a particular rock sample. Some day when I have the time I'd like to teach myself some of those old techniques for identifying minerals without a microscope - I'm sure they would come in handy.

Can you thank a reviewer?

Maybe this is a rookie question - most certainly it is - but when you learn very much about your own work from sending a paper off to review, is there an appropriate way to acknowledge someone who spent more time (and expertise) working on your paper than the co-authors have done? A way to thank a reviewer who has acted as an advisor?

Answer: Don't send off a chapter of your thesis to a journal.

Answer #2: If it's not rejected outright, on the basis that it is just a chapter of your thesis, and it takes a very long time to rewrite and re-review same, feel lucky, and improve.

ps. Will I outgrow the stage when I need this kind of help?
Answer #3: Only if I publish only where I am comfortable - not a near term option, given my recent research activities.

pps. Can I write a review which is simultaneously direct, stringent, rigorous and supportive? Especially when I am sent a paper to review which is clearly a chapter of somebody's thesis?

Answer #4: I must work on this point.

Field Fantastic!

Just back from Mozambique and covered in red dirt - I have only one question for you tonight:

What happens when a Pan-African pegmatitic granite intrudes a mid-crustal shear zone in the middle of the construction of Gondwana?

Answer: one of two things:

Those would be augen formed from entrained feldspar crystals in the intruding magma, or,

Those would be rafts of mylonite floating in a granite.

Snowball Earth Strata near Kogelfontein

Some time ago, in the middle of an igneous field trip no less, we were out on the coast of Namaqualand near the Kogelfontein igneous complex. The Kogelfontein rocks are Cretaceous, which to a South African is pretty much Yesterday, or in other words, that piddly small part of the geologic time scale that nobody bothers to learn. Did I mention that my students don't learn the Phanerozoic part of the time scale? And similarly, I never learned the other 80% of the time scale? Remind me to chalk that up on my list of SA-USA translation problems in English. I do feel like I've been accepted to some degree, with all my idosyncracies, because people don't correct me anymore when I say "Al-U-Min-Um"**. But I digress... it is a blog after all.

Anyway we took a detour to see this incredible outcrop of interbedded black turbiditic shales and clean, beautiful white marble. Yes, shales (sedimentary) and marble (metamorphic, or should I just say recrystallized).
This assemblage, Neoproterozoic* in age, is a key assemblage in the Snowball Earth story - a story better told by other outcrops in other places, perhaps, but there's evidence for it here if you accept it as such. The story goes that at 600Ma (give or take), the earth experienced a total glaciation - most of the continental landmass at the time was at high latitudes, close to the poles, and as earth cooled and entered the glacial period the continents were completely covered by ice sheets. If you're familiar with the concept of albedo - the reflectivity of the earth - you will know that rocks will absorb light and heat from the sun and re-emit it all as heat, warming the atmosphere. Ice, on the other hand, will reflect the majority of that energy back to space, and will not do the nice turn-light-into-heat action that bare land can do. The bare land bit is important here, because this is hundreds of millions of years before plants, or fungi, or any of those great heat collectors working for us today emerged onto land. So a planet with its land mass covered in ice is a very cold planet indeed, and has lost its means for warming itself from the sun's heat.

As the story goes, tectonics was still chugging away under all that ice, warming the oceans from mid-ocean ridge volcanoes and supporting tiny islands of bacterial life. The combined effect of the geothermal heat and the CO2 from volcanoes and life was eventually enough to break the cycle of cooling, and the planet warmed again. As land began to see the sun, the warming sped up and the oceans warmed up very quickly.

One of the fascinating things about CaCO3, that is marble, that is the most common mineral form of CO2, is that it is reversely soluble - that is, it dissolves more easily in cold water than in hot. That's the opposite of most everything, sugar, salt, most other minerals... So when the oceans were cold, there was a lot of CO2 dissolved in them. When the oceans warmed up quickly, all that CO2 was no longer stable in the dissolved state and CaCO3 - limestones - precipitated on the seafloor all over the world. We usually associate limestones with warm shallow places - coral reefs, etc. - but in the late-Neoproterozoic warming, limestones were forming everywhere, even in the very deep sea. Enter the outcrop at Kogelfontein.

The black shales here are deep water deposits (again, or so the story goes) that are very rarely found in association with limestones, anywhere in the rock record. Here they are together, repeated at least a couple of times: a shale, a limestone, a shale, a limestone. Or is it?

Here's trusty TA Duane pointing out the reason for the repetition. The reddish rounded lump he's standing on is the long thin hinge of an isoclinal bedding parallel fold - the axial plane of the fold lies in the plane of bedding.
The fold is ultimately doubly-plunging - it rounds off at both ends like a big sausage (that would be wors in local parlance) but there are others along strike. And in between, some beautiful evidence of tectonic interference with the stratal succession: shear foliations in otherwise sugary marbles, and strange little cuspate-lobate structures on ptygmatic folds (not sure what that folded bed is). That ZA 50-center is the size of a US quarter.


Here's a shot down the axis where a quartz-rich bed is desperately trying to maintain its radius of curvature in spite of the drag:


So the moral of the story is: earth warmed up, and here we are. Whether these marine seds actually provide anything more than circumstantial evidence for Snowball Earth and catastrophic warming of the oceans is still under debate. The other moral of the story is: don't measure section in an accretionary complex***.


*Neoproterozoic is about 1Ga -> Cambrian, for those who share my timescale bias problems.
** as opposed to "Al-Yu-Min-E-Um"
***I don't really know if it's an accretionary complex. It's supposed to be an along-strike equivalent to the Malmesbury Group down here in Cape Town. But that's an axe to grind for another post.

Geological Spouse

"Why do I always have to be 'For Scale'?"



Groot Winterhoek Reserve, Western Cape, South Africa, December 2007.

And what do you want to be when you grow up?

In the fall of 2000, I went to the GSA Meeting in Reno. I was 6 months out of college, 6 months into wage slavery under an egomaniacal boss in an environmental consulting firm. I knew I didn't want to stay where I was, but didn't really have a good idea of the transition from undergrad to graduate student, hadn't been a particularly good undergrad anyway. I remember a vague sense of disappointment from some professors when I put rugby ahead of school (time and time again). On the rugby team I was the leader, the decider, director of all things! In the classroom I was one of many, and not calling all the shots.

I didn't have any sense of the incremental pathway between a bad case of senioritis and professorship. I knew I wanted to chase my own ideas, regardless of the fact that I didn't have any! Without of view of that path, I never pictured myself walking it.

At the GSA meeting I met a new kind of character, one I had read about in John McPhee but didn't really see on the East Coast where I went to school. The old crusty cowboy kind, dirt in the beard, leather boots molded to his feet, plaid western shirt, plus or minus big lump of turquoise on bolo, belt buckle or pinky ring. I've always referred to them as GreyBeards, although some are neither grey nor bearded. This character is a bit of a composite, clearly. Here's my portrait of one, gruff, sh*t-talking, "good ol days" wildcatting, tall-tale telling, swaggering example (before his time, even): Don Foss in the field in 2001:

He's somewhere between Jules Verne and Deadliest Catch, if you get the picture. My composite character hovers somewhere between mining exploration and academia, with plenty of distrust for both sides. He is a desert rat. He has nemeses who look just like him. He might have an axe to grind about how things are done these days. He probably has a beard, or at least a mustache. He does not respond to attempts by Eager Young Geologists to charm him with their enthusiasm, but might be easily flattered if he is recognized by the same. He is 100% geologist, everywhere, all the time. He knows no other life.

In that last bit, I found a model, an identity. It explained, in so many ways, why even though I felt sooo far away from college (6 months, but a very transformative 6 months) I was having difficulty performing basic social functions, such as hiking and chatting. Or driving. Past road cuts. Or bidding a remediation job at a very well known archaeo-Olympic Tahoe ski resort without asking the age and mineralogy of the tills into which the UST were leaking. Geological details had moved from facts I had to cram for a test to welcome, necessary diversions to keep me entertained during increasingly repetitive jobs.

I iconocized a cast of males, many-post retirement, in part because of their pride in being a bit "dying breed", a bit TOO FIELD for even the GSA meeting. God forbid they ever meet the dark matter of AGU. But I digress. At the same meeting, I ran into peers I had known in college. Some of them were graduate students, presenting their first posters. I weighed myself against them, competitively. Sure, my grades were lower, but hadn't I helped her when she totally bottomed out on Norm Calculations? Hadn't I helped (another) her when we studied all night for the paleo exam? Yes, I had. I was just as good. So why did I feel so inferior?

I applied for grad school. I got one rejection, some serious wine-and-dining, and one tenuous, not yet funded option at a school I hadn't meant to apply to, in a subject which had been my weakest in college. STRUCTURE - A subject I had somehow understood to be the web in which all my other subjects were suspended but just couldn't get my head around at the time. But in a brief interview with a potential advisor (of which I did many, and so should you) I met somebody who presented the most interesting questions I had heard, in a fascinating field area, with deep global relevance for fundamental processes in HOW FAULTS WORK.

This potential advisor was not my iconic character in the sense I understood it - he was young (or so he looked!) and quiet. None of the bluster and pushy dictation of project (amazing project! big money and big papers!) I heard at other universities. But he asked me some pretty hard questions. Not about what i knew, but about what I wanted to know.

The project took me to new places, more meetings, new people. Realized that my iconic old men were probably rolling out the GB persona for GSA meetings, as much as I was rolling out my best "promising young student" persona. My icon morphed from a bearded old grump into something much wider and deeper. Best yet, I finally found the female side.

My first discovery was at the same Reno GSA all though I didn't recognize it at the time, I can still picture her so clearly. Long straight grey braid down her back, middle part. Corduroy skirt, birkenstocks, wool tights. Festooned with what must have been a brutally heavy thick beaded necklace of picture jasper, or some similarly non-precious ROCK. She was nearly hidden among a crowd of plaid dusty men in bolo ties. Bingo. The "Grey Braid". Many of these women are not "grey" in terms of being "old". I mean to say that they are venerable, they have a sense of history, and some are every bit as crotchety as the Grey Beards, whether old or young.

Once I picked up on this phenomenon I started watching for more women like her, and there they were. At a local society meeting I met an incredible retired USGS geologist with brightest red hair, wearing a sparkling gold ruffled blouse with a full slab of Green River Shale with a fish in it around her neck. My new fashion icons were generally younger than the original Grey Beards, maybe because there aren't as many women geologists in their post-retirement era at GSA, certainly there were fewer field geologists in their generation. I met a volcanology prof at a neighboring college - the first woman at the UofO volcanology field trip. She had a rattle snake skin on her office wall. She had dispatched this huge specimen by throwing her bowie knife through its neck while it menaced some not-so-supportive (male) fellow students. Hell yah! The Grey Braid mythology grew.

I met more and more women who struck me as heroes of geology. Of women in geology. My kind of geology. My kind of women. My reluctantly glamorous field camp mentor who did volunteer autopsies at the Nairobi zoo and carried her baby on her back to dinosaur digs. A USGS mapping geologist who carries a whip in the field and takes no prisoners. The great gun-toting field geologist women of Alaska, who move easily between tectonics and petrology, geochronology and geomorphology, present and past as if they can see the whole Great Land in four dimensions before them at any time and place. One while wearing a brightly colored vest she quilted herself.

These women all have striking stories behind them. Stories of finding their own way into doing the field geology they love, often through very circuitous paths, often making great sacrifices by leaving the straight-and-narrow career path. Each of them eventually created a niche for herself- maybe not perfect niche, but a balance between career and family and love that works.




I want to write a book about these women. Or rather, I want someone who can write to do it. I want it to be a big portrait book, like an art exhibit book, with beautiful photography of these women in all their non-precious jewelery, pyritized ammonite-wearing splendor. As a model I suggest Alison Owing's Hey Waitress! The USA from the other side of the Tray. I've been a fan of Alison's writing for some time, she writes these incredible anthologies of portraits which vary deftly from funny to profound, intertwining the stories to produce a portrait of a group of women without smoothing over the individual faces.

Why are the portraits so important, and why am I obsessed with Grey Braid fashion? Because it asserts so strongly the geologistness of these women, and the womanliness of these geologists. It represents a collective turning-of-the-back to mainstream ladies clothing, the clothes are functional, machine washable, there is almost a pioneer sensibility about the corduroy and wool. Layered on top of this functionality is a feminine flamboyance expressed in wacky color and irrepressibly geological, often uncomfortably heavy accessories. This look is every bit as vital and expressive as any form of fashion, and a good deal more individual than what my students are wearing these days.

In case you missed my birthday.