Pyrite

Our next step will be learning a bit about the individual minerals that make up the various rocks. The following question gives us a good start.

Q:
Hello. On a recent visit to a museum I came across a crystal called pyrite. I was, and still am astonished by the perfect cubes formed by the pyrite and I'm curious to know how it is possible for a crystal to form a shape as perfectly symmetrical and precise as a cube? I've been doing some searches on Google but I am unable to find any solid answers.
--Brent S.

A:

Pyrite is an important mineral for people looking for metallic sulfide deposits. If you successfully find copper sulfides, you will almost certainly first see a lot of iron sulfides: FeS, or pyrite. These sulfide minerals are usually called "secondary" - that is, minerals that form in the rocks after the rocks themselves are solidified. This often happens because metal-bearing fluids are moving through the rock - and either deposit minerals like pyrite in cracks (which when filled become "veins"), or slowly replace certain minerals already in the rock in a complex chemical process. Pyrite is often called "fools gold" because it fooled many of the early, uninformed people who thought they would go out and make their fortunes as miners. Think of the "49ers" who rushed to California when gold was found in Sutter's Mill near Sacramento in 1849. Pyrite, however, is more brassy than gold. It's is also angular - crystalline - and shiny when found fresh - in other words, when it is unoxidized. Gold is a deeper yellow in color, and found in flakes or occasionally as rounded nuggets in pans. Pyrite forms in rocks where there is little or no oxygen present. 

To explain pyrite's perfect cubic shape, I would have to show you one of those chemistry-class balls-and-sticks models to show how the two ions iron and sulfur fit together. The atoms are only one ionic shell-size different from each other - Fe is one level lower than S on the periodic table, meaning that it has two free electrons in the next shell out, while sulfur is missing two electrons in the nearly-complete next-smaller shell. For this reason, the ions of iron and sulfur when meshed together are virtually the same size. Think of a checkerboard with black being iron and white being sulfur - and then imagine in your mind a 3-dimensional version of this. Crystals grow molecule by molecule, so the next thin, molecular layer added onto the pyrite crystal cube can only form when each iron atom is matched to a sulfur atom. As the individual pyrite molecule in solution approaches the crystal face, the individual atoms will move and re-orient to make a perfect opposites-attract match. This guarantees not just a cube, but a PERFECT cube, at least to within an atom's thickness of all surfaces in contact with the solution where the ions are coming from.

If you actually saw a perfect pyrite cube, you either saw a sample very recently collected, or the sample was kept in a non-oxygen, probably nitrogen-filled glass container. The reason for this is because pyrite will slowly but steadily oxidize in the Earth's present (21% oxygen) atmosphere. It will literally turn to a brownish "rust", and the bright "fools gold" shine will be lost with time. The reason we know that the early Earth did not have oxygen in its atmosphere before about 2,500,000,000* years ago is because some pyrite grains weathered out of a rock in South Africa and were tumbled down an ancient creek, which rounded the cubic grains before they were compressed and consolidated into a sedimentary rock. When unearthed in a deep mine the rounded pyrite grains were still bright and fresh; if they had weathered out of a rock today and washed down a creek somewhere, they would be turned to brownish-looking iron oxides very quickly. 

* NOTE: If you are an American, you would call this number "two point five billion years" - but if you are English you would say this as "two point five thousand million years" - because for many countries where English is spoken, a "billion" means a million million. For this reason, "2,500,000,000 years" is generally abbreviated among geologists as "2.5 Gy" to avoid confusion. We will talk about this interesting oxygen transition-time later.

~~~~~ 

Rocks - a good place to start

It's probably a good idea to start with the fundamentals of modern geoscience: ROCKS and their derivatives. There are three main kinds of rock, and a lot of subdivisions within each. To explain them all would require a third of a book by itself, and a lot of pictures and diagrams, so I'll just summarize them here.

Q:

Dear Geologist,

Do you know who named these rocks, Igneous, Metamorphic and, Sedimentary?

Sincereley,

Elizabeth

3rd grade

A:
There are three main rock types:

"Igneous" appears to be first used in the 1660's, but it's not clear who started using it. It derives from a Latin expression that means "is fire." Igneous rocks include volcanic lavas and intrusive rocks that came up from great depth, but didn't quite reach the surface. Because lava reaches the surface and cools rapidly, it doesn't have time to form visible mineral grains. Intrusives, however (like "granites", "monzonites, and "gabbros"), are insulated by the earth they intrude into and have time to cool more slowly - and grow crystals. Sometimes these can be huge - individual crystals in a "pegmatite" can be 5 cm or more on a side. Pegmatites are almost always gorgeous to look at. Kitchen counters are often made of beautiful granites or monzonites; mine is a Labradorite Anorthosite" - a dark gabbro-like pegmatite with single iridescent Labradorite crystals as long as 10 cm on one axis. I was lucky to find this already in the house I bought when I moved to the Pacific Northwest.

"Metamorphic" derives from Greek, and was used first sometime before 1810. It comes from a word meaning "after" or "beyond" (meta), plus a word meaning "shape" (morph). Old-time miners described these rocks as "being stewed and cooked" - because they sort of look that way, like molasses and water stirred together. They form from igneous, sedimentary, or even other metamorphic rocks during deep burial in the Earth, where pressure and heat can cause the rocks to deform plastically. A "gneiss" is one example - a coarse-grained rock that frequently has the original sedimentary layers still crudely visible in it... if you step back far enough. A "schist" on the other hand may be finely layered from original freshwater mud or seafloor dead-creature goop, and can glitter in the sunlight from all the tiny grains of muscovite (white mica) that form in it during the pressure-heat cycle. These rocks are usually classed by the degree of metamorphism - how much the original rock has been compressed, stewed, and cooked - with gneiss found on the extreme end and something called "greenschist" on the near end. Metamorphic rocks are usually moderately ugly-looking - but interesting to the discerning eye of an experienced geologist. They commonly draw the eye to their curious character.

There is a place in the Catalina Mountains north of Tucson, Arizona, where from a distance you can see the original sedimentary layers in the gneiss that makes up the front (south end) of the range. If you get up close, you can't see this very well at all - you just see the coarse recrystallized final product of the metamorphism. There is actually an even more final product: as you move northward in the range, the depth of burial of this uplifted and tilted block of sediment came from ever deeper depths, until the gneiss grades smoothly into granite. A graduate student mapping this complex once came across a shape of a crinoid - a 400 million-year-old fossil - from the original sedimentary rocks. For geologists, to see all this happening in one place as a continuum of change (or metamorphism) is indescribably cool. 

Sediments.The word "sedimentary" seems to have been first used around 1820-30, but again, it's not clear where it came from or who first used it. It relates to sediment - rock that has formed from loose sand, gravel, or mud deposited by water or air. Eventually it gets compressed and cemented by other minerals in the fluids that percolate through it. Sedimentary rocks often look sort of "grungy" - some can be ultra fine-grained and very hard, like "limestone" (which typically has fossils in it), or hard and coarse-grained, like "sandstone", or thinly layered ("laminated") like "shale."

Rock Derivatives:

If you did a trench in the ground from the leaf cover on top to the bedrock below it, you will see gradually-changing textures ranging from something you can scratch with your fingers to something that you can't. The soft stuff on the top are the soils, and often have organic content from dead vegetation in them (typically this makes them dark to black from the broken-down carbon content of the organic matter). These soils come from weathering of these main bedrock types described above. The rock breaks down over long periods of time for many reasons, including freeze-thaw cycles, abrasion from sand in wind or water, or the acids from plant roots. Sometimes it can be carried in on wind or water from long distances away. Given time, soils can accumulate, build up (for instance in a large basin or valley) until the overlying weight of the younger sediments compresses the underlying material into a new sedimentary rock. Groundwater slowly filtering through these materials help cement them into rock by depositing minerals between the soil grains.

Altered Rocks:

I used the expression "stewed and cooked" above to describe metamorphic rocks, but there are rocks that are literally stewed and cooked. These are the "altered" rocks - rocks in which the original mineral grains are changed by heat and fluids moving through them. The heat source can be an intrusive punching up from the upper mantle; this heat sets the overlying groundwater in motion into circulating loops called hydrothermal cells. This water moving through the vast bodies of surrounding rock can "grab" minerals from a distant source and draw them towards the heat source. An intrusive can break the rocks it is pushing up against, and these fractures can quickly fill with minerals that "drop out" of solution as they move up into the colder fractures and cracks closer to the Earth's surface. When the cracks finally fill with these minerals, they become "veins". Gold and silver and copper hunters look for evidence of this kind of circulatory concentration mechanism to home in on where the rich mineral deposits are hidden. If they find altered rocks - the most grungy-looking of all rocks you will ever see - then they know they are homing in on the Mother Lode.  So: ugly can be beautiful in yet another place on this planet of ours.

I'll talk later about mineral deposits and how the form, but this will serve as a quick introduction.

~~~~~

By the way, you probably noticed that I gave the size of those pegmatite crystals in centimeters, and not in inches. As far as I know, the United States is one of only three countries on Earth that still use the archaic English system, along with Myanmar (formerly called Burma) and Liberia. Not even the English use the English system anymore. The rest of the world moved many decades ago to the metric system, of which there are two inter-related versions: the SI (the Standard International system that uses kilograms, meters, centigrade, and seconds) and cgs (centimeters, grams, seconds and centigrade) systems. In order to teach correct principles, I feel I need to teach you what all the rest of the world - and also the science agencies of the US Government and virtually all American universities teach and use. 

~~~~~

A Day In The Life - Follow-up

I received an appreciative response from the previous reply, including the guy's college paper based on it. I thanked him and sent this follow-up back. He had been preoccupied about what foreign language he must master to be a geologist; he also said he loved flying, and envied me the time I had spent in helicopters. I felt I had to disabuse him of both misconceptions:

Well, thank you for fulfilling a promise. That report was fun to read, and I agree that it deserved an A.

A few comments that it brings to mind:
1. The most important language you must master is English. I personally know several close-to-genius geoscientists, but they couldn't write their way out of a paper sack if their lives depended on it. If you figure great things out, but can't convey these things in a report, it adds up to a massive failure. Your English instructor may appreciate hearing that. My wife has an MA in English/Linguistics, and just recently earned an MS in Biology/Ecology. She reports that she always got praise for her writing from professors who acted surprised that a science student could actually write coherently.

2. I love to fly in a small plane too. I dislike helicopters so much because (a) they are much higher risk than a fixed-wing aircraft, and (b) are so noisy that without a flight helmet (as happened to me frequently while living and working in Venezuela) the noise levels would make me physically sick, and leave my ears ringing for hours after landing. By comparison, being in the deep jungle or the deep desert (I also crossed the Empty Quarter in Saudi Arabia three times) the utter and profound silence was always wonderful. I should amend that: the jungle is silent during the day, but very much comes alive at night (I recently published a book about living and working in the Venezuela jungle, an eBook with Barnes & Noble).

3. When you get to Ohio State, a good friend of mine is a professor of geophysics there: Jeff Daniels. Say hello to him from me.

~~~~~

A Day in the Life of a Geoscientist (Interview)

Q:

First of all I want to give you a sincere thank you for giving me some

Time out of your busy schedule to do this. Out off all the university

professors I emailed you are the only one that responded. This is truly

an honor to get a response from the USGS who I hopefully will work for

in the future. The first question I have is:

1. Can you describe a typical day on the job?

I'm probably somewhat atypical, but I'll try to answer as best as I can. Of course it depends on what day and what year it is. From 2002-2007 I served as Chief Scientist for Volcano Hazards for the US Geological Survey, and any given day was 10 - 18 hours long. Most of it involved management and paperwork, occasional exhilarating visits to Mount St Helens, Kamchatka, and Chile, and long, very arduous trips to Hawai'i and other centers that I supervised. There was no beach time in Hawai'i, by the way; I was one of the few people who did not look forward to going to Hawai'i.  

When I completed my 5-year Chief Scientist assignment I reassigned myself to be a research geophysicist. Now that I'm not stuck with 10-hour-per-day bureaucracy, what I do depends on whether I am in the office or in the field:

A. In the office: I generally work on analyzing or processing data and w

riting/editing manuscripts, preparing scientific presentations, using c

ommercial and technical software packages. I am also an associate editor of t

he science journal "Exploration Geophysics", which takes some time each week to r

oute, rate, and process manuscripts submitted for possible publication.

B. In the field: an example might be a week spent inside Mount St Helens' crater - usually but not always working out of a helicopter

- where I either helped conduct a s

elf-potential survey, or conducted my own controlled-source a

udio-magnetotelluric soundings to map where groundwater (and which kind) m

ight be found down to depths of  up to 900 meters. I have also worked a lot in 

Alaska and in northern Sonora, Mexico, operating primarily in Spanish. I was the USGS science mission chief in 

Venezuela for three years, and spent a lot of time in the deep Amazonas jungle: an incredibly g

orgeous and awesome place, but also incredibly dangerous. I was the deputy USGS s

cience mission chief in Saudi Arabia, frequently working on the Iraqi or 

Yemeni border, mapping phosphate or gold resources, or searching for g

roundwater. My kids had to complete high school in a boarding school in 

Switzerland. As a result one speaks Mandarin (he was a Mormon missionary

in Taiwan) and the others all speak French, Spanish, and Arabic to varying degrees. One also speaks Czech and Slovak.

2. In the geology field what do you enjoy the most and what do you

Enjoy the least?

Most: Being a physical detective. Being the first to image some feature under the ground, or first to calculate an estimation of undiscovered mineral resources. Getting out into remote field locations that are always beautiful, awe-inspiring, and occasionally terrifying (Alaska, the Venezuelan jungle). These are a huge improvement over a desk-job, but you will get physically eaten up in an all-field-work existence. 

Least: Helicopters. Bureaucratic paperwork. Example: being required to take an on-line driver safety course. Go figure.

3. In the research that I have done i would like to go into the oil

industry. Do you consider this a good choice and if not what would you

recommend?

"Oil patch" as we call it is characterized by lots of money, and access to f

antastic physical resources. You would live in a few locations: generally Texas, 

Louisiana, Denver, Alberta, or the northern plains of the US. Increasingly you may find oil-hunters working in Pennsylvania and surrounding states in the US - fracking the Marcellus Shale for gas. A downside is that you are doing m

ost of your work on an oil-rig or in an office. 

There is also a smaller field of mining geology/geophysics, which has the upside of great field e

xperiences and the downside of a highly-fluctuating market (and therefore u

nreliable long-term employment with the same company). 

In between the two is what I would call "environmental geology": g

eo-engineering, waste-management, hydrology, etc. For a year I served as president of the 

Environmental and Engineering Geophysical Society, and the m

embership included people worried about bridge foundations and non-intrusive archaeological s

ite mapping - and about 20 FBI agents interested in "forensic geophysics" 

(finding bodies under concrete slabs, etc). There is also a significant s

ub-industry of geophysics that focuses on mapping unexploded ordnance: 

Finding IED's and land-mines. This seems risky, but it generally is not: that's why you use geophysical gear to find them.

4. A foreign language is required for the BS degree at Ohio State

University. What language do you recommend I take so that I could

possibly have an advantage over others entering the field?

For your generation - if it's available - I would seriously consider Mandarin. The grammar is relatively easy, but the tones and character-memorization make 

it as hard as Arabic. I speak French, Spanish, some Arabic, and a smattering 

Of Russian and Mandarin. The language that you will use the most often if you a

re in the united states is Spanish. I use this all the time.     

5. I am currently a 33 year old man who is a front end manager at a

Grocery store. This past year I realized that this isn't what I want to

be known for. I have always had a great passion for learning about the

Earth and the science of it all. However I do not want to be in college

forever. In your experience is a BS degree enough to get me in the

industry and and make enough money to pay the bills? I guess what I am

Wondering is do you think I will be able to find work with a BS degree?

A Masters degree is probably a safer bet, but it is taking longer than just two additional years to get an MS these days. A PhD is helpful for a higher s

tarting salary, but you can also over-qualify yourself with one. You must b

alance supporting a family while in school, and can you recoup your costs l

ater with a higher salary? I can't tell you off-hand what income is for a BS i

n geology these days, but would guess somewhere between $30,000 and $60,000. 

It depends a lot on where you work - for the oil industry, you'd see a substantially higher i

ncome.

6. Is there much travel involved in the geology field? If so what is

The best and worst places you have gone.

If you are a field geologist - most anyone starting out in the industry - you will travel a *lot*. I switched from physics (home e

very night from a lab) to geosciences (sometimes gone for 3 weeks at a time), a

nd it took my wife time to adjust to this (me too!). 

I have always been somewhat adventurous, so have welcomed opportunities to do f

oreign travel. This always involves a lot of adjusting - to cultures and to d

ifferent safety levels, and has greater highs but also greater lows (I nearly d

ied several times in the jungle, for instance). It was good for my kids -- it b

roadened them out quite a bit. One is a professor right now in Australia, for i

nstance, and another speaks French most of every day living in Quebec. 

Visiting places like Venezuela and Kamchatka and the Aleutians and southern 

Chile and Greece and Saudi Arabia have their upsides - they are always i

nteresting - but their down-sides can be really "down" - and personally quite d

angerous sometimes.

7. What do you think employers look for in a great geologist.

Someone with a breadth of experience in geology, unfortunately - a classic Catch-22 situation. They want someone who is willing to work hard and go to d

ifficult places. Someone with maturity they can count on - I'd say you have an edge there.

8. What is it about your work that poses the most difficulties?

Paperwork, bureaucracy, and lack of financial resources to do much field work. It's hard to be a geoscientist if you cannot collect new data. W

hen I started with t

he USGS my operating expenses far exceeded my salary; now it's just the o

pposite.

Again thank you for this interview. I know that this is just for a

Basic english class, but since it involves you would you like a copy of

The final draft that i will be turning in to my professor at Columbus

State community college in a couple weeks?

Cory B

Id be happy and honored to see it. 

~~~~~

What Is a Geologist?

Q: What are geologists?
     What does a geologist do?
     Thank you!
     Barbara S.

A:
Geologists are what geologists do - pretty much the same thing as far as answering your two questions.

Geologists map the rocks and soils on the surface of the Earth, log (examine, analyze, and describe) cylindrical rock cores taken up from drill-holes, and sample sediment in streams and rivers. They try to figure out the ages of rocks and structures that the rocks are shaped (bent, folded, and faulted) into.

Some geologists measure geophysical fields and chemistry: they are called geophysicists and geochemists. They may do this by dropping sensitive instrument probes down deep drill-holes, and they may do this by making instrument measurements (or taking samples and chemically analyzing them) all over the Earth's surface. Fundamentally, they are interested in what's going on underneath the Earth's surface. With some experience, seeing what is on the surface or within the near surface regime can tell you what is going on much deeper than you can easily dig.

They do this in almost all cases for practical purposes:

• Where can oil be found? 
• Where is the next mineral deposit so we can drive cars made of metals? 
• When will the next-door volcano explode?
• When did the next-door fault rupture again?
• Why does my water taste like chemicals are in it?

As this last line of inquiry suggests, some geologists are specialists in groundwater: they are called hydrologists. They want to know where the water lies, where it is moving to and how fast, is it being recharged, and are there any pollutants in it?

The objective of all their work is to better understand:

1. What the history of the landscape is,
2. What lies underneath that landscape, and
3. How do these things interact?

The end result is most clearly manifested in how well you live: Do you live in a heated or air/conditioned house? Do you drive a car?

To put things into blunt perspective, there was a political dog-fight going on in Tucson, Arizona once. Some people objected to a mining company developing a copper mine near (but not in) a national monument. The argument turned very rancorous, with political figures and newspapers being drawn into the fight. One day, bumper stickers appeared with large black letters on a yellow background. On top, in large type, it said "BAN MINING." Beneath that, in smaller letters, it said "Let the Bastards Freeze In The Dark."

Now, I'm probably more ecologically sensitive than most people, because I've seen first-hand the damage that uncontrolled mining has done to the deep Venezuelan jungle, where I lived for three years. However, I also have difficulty living with hypocrisy:  people who complain about logging, while they themselves live in heated, wood-frame houses, bother me. 

The answer, or course, lies in sustained, planned development: balancing everyone's needs including the aesthetic joy of hiking in a wilderness... but also ensuring the right to drive to the trail-head. 

~~~~~

A Career as a Geoscientist

Q:
Hi, Im interested in studying a career in geology, Im 39 and I would like 
to know to your opinion the pros and cons of this career, and also Im
pretty weak at math , so I wanted to know what math subjects should I
study to prepair myself if I decide to enter college. Thanks and regards,
Trevor

A:
A career in geology is fun, and one of the advantages is it gets me out into remote - and usually amazing - field areas. Sometimes these can be dangerous (rattlesnakes, falling off a cliff, 600-kg bears, helicopter crashes etc.).

The basic minimal requirements for a job would be a BS in Geology, but a Masters Degree would get you a much better chance of being hired as something other than a low-level technician.

This education must include several things:

1. Yes, some Math. You would have to get decent grades up through calculus and statistics at a minimum. Surprisingly, geometry and trigonometry are used all the time. Geologists 30 years ago could get away with less, but the field is becoming ever more very technically oriented.

2. English and Composition. If you can't write legible or coherent reports about your work, no one will know what you did. No one would hire you, and if they did, they wouldn't keep you if you couldn't write well. People will quickly judge you by your grammar - for instance writing "Im" instead of "I'm" in a sentence.

3. Computer literacy. You may not have to code in C++ or VISUAL BASIC or JAVA (though that would definitely help), but you MUST be able to operate complex software systems designed for geology, geochemistry, and geophysics. This implies very strongly that you must also have good grades in...

4. Physics, and

5. Chemistry.

Once you get through these basic requirements, the geology classes themselves will be incredibly FUN!

However, it's sort of like that basic physics Conservation Law: There Ain't No Such Thing As A Free Lunch. Anything worth something requires hard work to get it. A BS takes 4 - 5 years, an MS takes at least another three years, and a PhD takes another three or four years after the Masters Degree. After that, you will have to plan on starting on the ground floor, which may include riding a drilling rig and logging cores in a remote area (that's not so bad, actually - you get to read a lot). Or like me, it may include spending three years in a very dangerous jungle assessing gold resources.

~~~~~

Let's Start

There are about 60 individual scientists who work for the US Geological Survey who volunteer to answer geology-related questions on their own time. Typically every week I receive a series of questions, some of them spam, and respond to them. The time I spend on answering these questions I then make up for by staying at work longer that day.

There are some general rules:

• Don't do someone's homework for them,
• Copy your replies into a large database for other volunteers to tap into,
• If you can't answer a question - it's not something you are an expert in - then forward the question to someone who CAN, and 
• Do your best to answer real questions.

That last one is because some people are not really asking questions, but using the AAG link to stand on a soap-box and expound on a pet theory.

About 40% of real questioners identify themselves as belonging to Mrs. So-and-So's 5th Grade class in Hoo-Funkie, Louisiana. About 40% of questioners are adults - like a majority of living human beings, they are interested in the world around them and are seeking answers to questions. About 10% of questioners send a blurry photo (typically) of a rock and want us to tell them what it is. The last 10% fit none of these categories and from among those I get some of the greatest mental stimulation - I take time to learn more about the subject and then take care to craft a helpful answer.

I had a roommate at Berkeley who one day in a conversation described himself as "onmi-sexual." When I looked quizzically at him, he elaborated that this meant boys and girls, dogs and ducks. Though I was somewhat grossed-out (Ron did most things weird simply to offend his thoracic-surgeon father; he also declared that he didn't believe in the "germ theory"), I had no problems with that as long as he stayed on his side of the bedroom and stopped peeing on the bathroom floor in the middle of the night. 

However, along a similar vein I would classify myself as an "omni-scientist" - perhaps an "omnivorous scientist" would be better, as I'm interested in everything to do with science. I actually got to a MS degree in high-pressure solid-state physics before I decided I would go nuts working in a lab for the rest of my life. Don't get me wrong: I do lab work and even enjoy it (if I have my iPod with me) - but I also love working in the deep jungle and in the deep desert.

By happenstance, I was visiting at my in-laws house in California one Christmas and picked up my wife's brother's introductory geology book. I was fascinated, and read it all the way through. Not long afterwards I switched schools to one that had not two, not three, but FOUR off-shoots of traditional physics. In those days, to get a PhD you had to specialize in some recognized field of study; the multidisciplinary college had not really been invented yet. Though I read most everything I can lay my hands on about astrophysics, cosmology, and archaeology among others (I have even published peer-reviewed scientific papers in these subjects), I more or less settled on geophysics for a life-path. Technically, my PhD is in "Geosciences" - the theory being that with a PhD you should know more or less every subject in the general field of Earth science. 

To that end, I have a habit of answering virtually all of the questions in Ask a Geologist that come to me (I'm weakest in geochemistry and optical microscopy). Over the years I collected a large number of these replies, and queried our AAG coordinator and other participants about joining me in writing a book on the subject. Our coordinator, Rex Sanford, demurred, saying that he was mainly an IT specialist - and thank heavens, because he has built a nearly automatic system to collect queries, filter much of the spam, and parse out the questions that come in to respondents like me. I contacted others who Rex said had handled a lot of questions, but they all said they didn't have the time to work on a book. 

I guess that means you're stuck with me. I hope I won't disappoint you.

For the Ask-a-Geologist website, go here:
http://walrus.wr.usgs.gov/ask-a-geologist/

For more on my background, you can get a summary at my Wikipedia page:

http://en.wikipedia.org/wiki/Jeff_Wynn

For the Full Monty, you can churn through my USGS Professional Page:

http://profile.usgs.gov/jwynn

As a community service, I also teach women's self defense and advanced Jujitsu:

http://vancouverjujitsu.org/html/instructors.htm

Now let's see what I can tell you about the fascinating and virtually endless world of Geoscience!

==Jeff

~~~~~