Geological Photography Field Trip

Today I'm at the Geological Society of America annual meeting, and attended the short course/field trip on Geophotography.  It was led by +Ellen Bishop , +Marli Miller , and +Stephen Weaver , all of whom are talented photographers specializing in geological work.  Look them up, their work is really fantastic.

I first got interested in photographing geologic subjects when I began teaching a decade ago and found it was really difficult to find good quality photographs of the various features I was trying to teach my students.  Most upper-level geoscience textbooks only provide black & white images, and of course they don't provide multiple images of all the various features one might want to view.  Finding good photos of all the geology things is really, really challenging, and students need to see lots of examples.  Lots!  Fortunately there are websites like the Earth Science World Image Bank, the Earth Science Picture of the Day, and the EGU Imageo site, but there are still lots of holes to fill for good quality photos of geologic subjects.  So my passion for geoscience education has led me to try to contribute.

I've put out a number of Geology Field Photos on my Google+ page (search Carrigan #geopic) in the past couple of years.  It's been rewarding to share these with my followers.  I've also blogged about that effort in the past, so no need to say more here.  I will continue to primarily share my geophotos in that manner.  Don't get me wrong - I don't have some overinflated ego about the quality of my photographs.  I enjoy doing it, but I've got a lot to learn and a lot of room for improvement.  

Geological Photography essentially blends aspects of the art of photography with the science of geology - how do we make visually appealing, high-quality photographs of geological features.  Although I've been interested in this for a few years now, it's only been in the past year that I've wanted to push my photography skills beyond shooting with automatic settings and little to no editing.  The fact is that with a good camera and a decent eye, you can take a lot of decent shots that will be beneficial for student learning.  That will only get you so far, so this past year I've been learning how to take photographs manually, to control all the various settings - aperture, shutter speed, ISO, white balance, etc.  OK, I take that back - I still let my camera control the focus.  My few attempts at manual focus have been disastrous.

I'll tell you one truth: when you go from fully automatic to fully manual, the quality of your photos will decline at first!  My wife can attest to this, as the pictures of our kids from this past year were sometimes, well, not so good.  It takes time and practice to learn new skills, and I'm definitely still on that journey.  I've taken a lot of shots over the past year where the exposure was just all wrong.  Sure, you can adjust some of those things in software afterward, but the best thing is to get it right when you first take the shot.  Today I was in full manual mode; no more training wheels.  We left in the morning and headed out to Roxborough State Park, the geology of which is a lot like other areas of the CO Front Range - upended Pennsylvanian Red Sandstone Fountain Fm., followed by various other units until you get to the Dakota hogback.  Lots of good scenery to photograph, and I purposefully did a lot of experimenting with various settings.  Definitely some real buggers, like the times when I adjusted the aperture but not the shutter speed - oops.  I still need to look through the bunch and pick out the good ones and do some editing, but it feels obligatory to include some photos in a blog post about geophotography, so here are a couple of shots from today that aren't too bad:  

Tomorrow we head to the convention center with laptops and our RAW files and are learning about post-processing of digital photos.  Here's an area where I know next to nothing, so I'm really excited about this.  Hopefully I'll have more & better photos to share in the future.

Anyone out there care to share their experience photographing geologic subjects?

Radioactive Decay of Candium

Last week, I posted on G+ a brief preview about an in-class learning activity that I do in my geochemistry course, which I refer to as the "Radioactive Decay of Candium".  The idea is to use a student-centered activity in class that is enjoyable & interesting in order to learn about how radioactive decay works.  I didn't originate the idea, rather I've taken the main idea from an activity on the SERC geoscience education website & modified it a bit.

The activity begins with a very short discussion about how radioactive decay works, but really I want to get them going quickly, so we talk about the fact that each m&m has a 50/50 chance of landing m-side up or m-side down, a lot like flipping a coin.  So I give them each a couple hundred pieces, a bag, and a couple of pieces of clean, white paper, and a handout.  Their job is to count the pieces, place them in the bag, shake them up, pour them out, remove those showing m-side up, and count the ones that remain.

Fig 1. Science in progress!

Those that remain are placed back in the bag & the process is repeated.  Each time, they record their results on the board.  After they reach zero m&ms, I give them a second handful of pieces, they count those & then add them to their first pile and do it all over again with a larger sample.  At this point, they might have ~300 pieces.  This time, however, those that "decay" each turn might get eaten.  After all of the groups (I usually have them do this in pairs) have finished, everyone records all of the data.  We then walk through the graphs they have to create with the numbers, now working on their own.  So here's a graph of all the trial runs, including the "class total", which is just a sum of all pieces on each step.

Fig. 2.  Decay curves of Candium for all experimental runs.  

This obviously shows the number of pieces that remain on each turn after they shake them out & separate out the "decayed atoms".  Then I have them calculate the percent of the total number of "atoms" that have remained on each turn, which looks like the figure below.

Fig. 3.  Percentage of total atoms that remain on each turn for all experimental runs.

I like the comparison of the two graphs, in that it shows that no matter how many atoms you start with, the decay in each case is the same percentage.  It's a fun activity that helps students really connect to the idea of radioactive decay, and a tasty one too!

New EarthCache Developed: Hill City Fold, Black Hills, SD

I've mentioned a couple of times previously that I spent the month of June out in the Black Hills of South Dakota, teaching field camp for Wheaton College at their Science Station.  It was a great experience and hopefully I'll get to give it a go again in the future.  I've also written recently about EarthCaches, a program between the Geological Society of America and Geocaching.com.  While in the Black Hills, I logged a number of EarthCaches and also recorded information about a couple of places in order to place some new ones.

The first one I've set up is a roadcut on Highway 16/385 near Hill City, SD, within the Black Hills.  The roadcut exposes a fantastic example of a fold.  EarthCaches must have an educational component, and for this one I ask the geocacher to identify whether the fold is a syncline, anticline, inclined, or recumbent, so the geocacher has to learn something about the axial plane of a fold and be able to recognize it in the rocks.  So, forgive me if I don't post a picture of it!  The cache description contains enough information for geocachers to know what these terms mean, so by observing the fold in the field this ought to be easy to answer this question.

I also ask the cacher to measure the horizontal length of the fold as exposed in the roadcut.  One of the easiest ways to measure distance over land is with a GPS, which every cacher ought to have with them in the field.  In order to navigate toward a point of interest, geocachers often enter the coordinates of a location into their GPS to set a waypoint, tell the GPS to "GoTo" the point, and the GPS will then tell them how far away the point is.  This obviously makes it easy to see your distance to the point decreasing as you get closer.  I have cachers use this technology in reverse - establish a waypoint (POI) at one end of the roadcut, tell the GPS to "GoTo" that point, and then they themselves physically walk away from it to the other end of the roadcut.  When they reach the other end of the roadcut, the GPS will tell them how far they've gone.  This exercise hopefully helps cachers to learn to use GPS technology in a way they might not have thought of before.  After all, why would I tell the GPS to "GoTo" a point, but then I myself "GoAway" from it?  It isn't an intuitive use of a GPS but works really well.

The new EarthCache was just approved, so we'll see how long it takes someone to visit the site and log it.

A slight cringe at a Yellowstone National Park sign

I've been back from my month long trip to South Dakota & surrounding areas for a couple of weeks now.  There's lots of great geology to talk about, so a lot more will come as I get around to it.  But for now, just a post about a sign at Yellowstone that reads:

"Deep within the Earth, heated water dissolves and then transports silica, the same mineral found in sand and glass, to the surface.  During geyser eruptions, silica is deposited around narrow 'vents' or openings.  Over time this mineral, called geyserite or sinter, forms mounds of varying sizes and shapes."

The sign that's wrong about minerals.

EEeeeeeessssshh!!  If you zoom in on that photo above, you might be able to make out the text under the central picture of Castle geyser.  As to the science on the sign, the basic idea that hydrothermal fluids dissolve & reprecipitate silica is fine, and this sign probably communicates correct information to the reader for the most part.  However, it perpetuates a misconception in the understanding of what a mineral is.  "Silica", "geyserite", and "sinter" are NOT minerals.  At least, not in the geologic sense, and since this sign is communicated geoscience information, it ought to use geologic terms correctly.  

Silica is a chemical compound, with the formula SiO₂.  All minerals are chemical compounds, but chemical compounds are not necessarily minerals.  For one thing, minerals have to be solid.  So if silica is dissolved in water, it's not a solid, it's now a component of a liquid.  Using the term "mineral" in this fashion is a bit like the way the term is often used in nutrition, where various elements like calcium & iron are often referred to as "minerals".  They are sometimes referred to as "mineral nutrients" or "dietary minerals", but neither of these terms are very satisfying either.  I'm not sure why the term mineral ever got used in this fashion, since none of the "minerals" referred to in nutrition are minerals, they are simply elements.  But again, this sign is attempting to communicate geoscience, and in geoscience if something is dissolved in a liquid, it is most definitely not a mineral.  


Now suppose our silica is in a solid form, does that make it a mineral?  Not necessarily.  Several minerals are made of silica (quartz & its many polymorphs), but silica itself is not a mineral, it is a chemical compound.  The reason silica is not a mineral is because minerals are defined not only by their chemical composition but also by their atomic structure.  Quartz & all those other silica polymorphs each have a distinct atomic structure.  Silica can also form solid materials that are not minerals, such as opal.  Opal is a solid that does not have a crystalline atomic structure.  Glass is another solid material that also does not have a crystalline atomic structure.  A crystalline atomic structure means that the atoms are all lined up and bonded together in an orderly fashion that repeats itself in three dimensions thousands and millions and billions of times, depending on the size of the grain.  Non-crystalline solids are solids where the atoms are a bit more jumbled up & irregular.  So minerals are defined by their chemical composition AND their atomic structure.  Silica is a more general term that only means chemical composition, but doesn't specify the atomic structure.  


Geyserite is also not a mineral.  "Geyserite" is something of a generic term referring to the solid silica that is deposited around geysers.  So this is at least solid, but it still isn't a mineral.  Most of geyserite is the material known as opal, and as I already explained above, opal is not a mineral because it does not have a crystalline structure at the atomic level.  


Sinter is another term that really refers to the porous nature of the geyserite, so this is a term that's really about the physical attribute of the aggregation of the various grains of opal.  So really, this is a rock term.  


So what is a mineral?  That I'll save for another post.  


But why write this post?  Who cares?  I teach a course in minerals to undergraduate geology majors.  One of the most important concepts of the course is "what is a mineral?" and what is not.  Definitions, especially in science, are extremely important.  A geologist's understanding of the term "mineral" can't be gray & fuzzy; it needs to be precise & accurate.  Many geology majors grow up with an interest in natural phenomena & are likely to see signs like this one at Yellowstone, and they get these confused definitions in their heads.  In education, misconceptions (things we think we know but are actually wrong) are really, really hard to get out & get corrected.  


On the first day of my mineralogy class, I ask my students to simply list the name of every mineral they can think of.  When they took their introductory geology course, they learned about 20 or so minerals, so this exercise is intended to require them to recall that information.  But the answers given often include things that are not minerals.  Answers like "quartz, feldspar, granite, calcium" sometimes show up.  The first two are fine minerals, but #3 is a rock and #4 is an element and neither of them are minerals.  This shows that the students don't have a clear & precise grasp of what a mineral even is or is not.  In my experience, this is pretty typical for students at this stage of learning; hopefully at the end of the course they've got the concept mastered!  

But beyond the students in a mineralogy course, confusion about science abounds in our society.  A basic knowledge of the differences between minerals, elements, & chemical compounds is junior high level science.  So I cringe when these differences are misrepresented on a sign in a national park that's intended to communicate scientific information to the public.  The problem basically boils down to this: there's a precise, careful definition of the term that's used by those who know, and there's the loose, flimsy definition of the term that's used more in the general public.  A sign communicating geoscience to the public I think ought to be a bit better.

EarthCache

I've long been a fan of one of the lesser known types of geocaching, the EarthCache.  Unlike their more well known counterparts, there is no container of tupperware hiding in the woods.  Instead, the cacher must visit a location for its geological significance and answer a few questions in order to log the cache as a find.  I've logged a bunch of them and set up three of them myself at some of my favorite geological spots.  I guess they bring together two things I'm passionate about:  Earth science and education. 
Last week I returned home from being gone for a month, where I was teaching geology field camp for Wheaton College at their science station in the Black Hills of South Dakota.  While out there, I was able to find several EarthCaches.  So far I've only logged a few of them, and I've got about a dozen or so more to go.  It can take a bit of effort to finish them all up, which is why a couple of other geocachers I know have said they hardly ever log them.  But I find them much more rewarding than the regular geocache. 
I found two locations while out there that will make for excellent EarthCaches.  I don't want to give too much of them away before I submit them, but one is an unconformity in the Black Hills and the other is a fault in the Bighorns.  More to come maybe after I get them submitted.