GeoSphere is Moving!

I have an announcement: I am moving to a new home at the European Geoscience Union's (EGU) new blog network! I am super excited to join this new network of geology blogs and continue to write about geology, one bite size chunk at a time.

http://blogs.egu.eu/

My new URL: http://blogs.egu.eu/geosphere/

When I began this blog my mission was to attempt to bring geology into the public view and facilitate communication between scientists and the public one post at a time. I have always been involved in science outreach and so I began blogging as a personal way of engaging anyone who read my posts. I sincerely hope that by moving to the EGU network I'll be in a better position to continue with geology communication and instill in those who read my love of geology while also getting people interested in the earth sciences.

I'll be joined by two other blogs to start the network in addition to the EGU's own blog. I am not sure what their respective URL's will be but I'll post them here once I know. I also intend to keep this site active as an archive of my past posts.

Thanks for all of the support and encouragement over the past year and a half and I hope that you'll follow me to the EGU!!!

Matt

Accretionary Wedge #50: Field Camp / Trip Moments

Evelyn Mervine is hosting the 50th anniversary edition of the Accretionary Wedge at her blog Georneys. The topic of the wedge this month is a nostalgic one: talk about a fun field moment. Wow! There have been so many fun moments, in fact, every time I have been to the field its been fun...even the days that didn't seem so great at the time now are just fond memories.

I remember the first field trip of my geology undergrad. Looking even further back I remember the first time I went mineral collecting in a quarry (I was only 10). Over the years I have been in countless old quarries and mines, stopped at hundreds of outcrops and been on many educational geo field trips around North America and the Caribbean. So really the problem is not to tell a fun field story, but how can I tell just one?! I can't!

My first trip

My first geology related field trip was to a limestone quarry an hour north of my home. I was 10 years old and was a major geology nerd as a kid...not much has changed. I had just joined up with the Peterborough Mineral and Fossil Club and this was one of the many collecting trips that the club went on each weekend. The trip was to an active quarry so I had to make sure that I was wearing a hard hat and steel toe boots. We were there to collect pyrite cubes. In hindsight, this was the perfect first trip for me. We were collecting flashy gold pyrite cubes in the limestone which made things easy for me since I didn't have the strength back then to swing my hammer like I do these days. Plus, there was the certainty of finding something that looked cool and was easy to identify. I have been on many collecting trips since and usually the rocks are not so soft and the minerals are not so flashy. Unfortunately, I don't have pictures of my first trip so you'll just have to imagine me, my dad, and about fifteen retired men and women in the quarry wandering around looking for the glint of pyrite.   

My first undergrad trip

The first trip of my geology degree was to a spot not far from the school. I went to Queens University in Kingston, Ontario and the trip was part of a second year course aptly titled "Field Methods". The course involved weekly five-hour field trips to local sites were we would map, measure and identify the rocks in the area. It was a hard course, especially since we were all new to the field and were being asked to do a lot, but in hindsight it was a fantastic learning experience. Fond memories include the prof continually yelling from underneath his umbrella and a cloud of smoke "get in the ditch". But I digress. Our first trip was just up the road to place called Joyceville, where we took notes on the syenite outcrop, made a map and talked about joint sets and glacial striations. One thing I really remember was the rain. It poured the entire five hours and at the end all we could do to stay warm was huddle in groups of five or six and try to keep our field books dry enough to write. Sound familiar? I think pretty much every rookie geologist has an experience like this. If only I could find the field book that has those notes in them. 

Bermuda trip

Fast forward a few years to the start of my final year of undergrad. I was lucky enough to go on a trip to Bermuda as the conclusion to my carbonate sedimentology class. It was led by world experts in the field and is in fact known across Canada as the best carbonate trip in the country for students and professionals alike. The beauty of carbonate systems is twofold: "they are born, not made"  and that you can see their development in action. All you have to do is strap on a snorkel and jump overboard, which is exactly what we did. This trip is a highlight of my geological career so far and was one of the most enjoyable field experiences I have had...how can you beat doing geology in the Caribbean and spending all day snorkelling around reefs?

Doing field work!

Thrusting

This became a weird tradition for upper year field trips in the department, at least when my friends and I were on the trips it did. I have no idea if it goes on to this day. However, let me explain before you get any strange ideas about what my friends and I were up to on these trips. We were working in Quebec and upstate New York looking at evidence of the Taconic orogeny during the Ordovician. If you have ever done field work in these areas you know that thrust faults abound. In fact, the whole area is nothing but thrust faults. So, when we would do group photos everyone would lean in the direction of thrust...essentially creating a human thrust fault. See the pictures below...

Everyone do the thrust! Arm gestures are crucial.

Extreme group thrusting!

TA'ing

Things are different now. No longer am I the cold, wet undergrad trying not to rip their map. I am the one yelling "get in the ditch" these days, and trying to coach the next generation of geologists as they learn some field skills while trying my best not to laugh as they bumble along. Being a field trip leader is as much fun as being on a trip. I really enjoy teaching people and explaining all of the amazing things that rocks, sediment, etc. can tell us.

I have been on lots of other trips as well and I enjoy telling stories about them all so perhaps I'll post in the future with some more field trip moments.

Thanks for reading!

Matt

Geology Photo of the Week #5 - Sept 23-29

The fifth edition of the Photo of the Week is of a fantastic trace fossil that I was shown while on a 4th year field trip in my undergrad. We were travelling around Quebec looking at evidence of the Sauk-Tippecanoe unconformity and the Taconic orogeny during the Ordovician. We traveled from Kingtson to Quebec City and spend a few days in the area exploring all of the fantastic geology around and even within the city.

The trace fossil, which is not of an actual organism but rather evidence of its behaviour, was seen at a stop about half way to Quebec City. I don't want to give away the exact location since we hid the fossil around the outcrop for future groups of students to use when they visit. The fossil is called Rusophycus and is a trilobite resting trace. Trilobites were a very common, bottom-dwelling organism during the Ordovician, which ran from 488-443 million years ago. Sometimes, the trilobites, which had a hard exoskelton would dig themselves little holes, presumably to rest in, and these are preserved today as deep indentations in the rock that were then filled by mud and preserved.

A superb Rusophycus trace fossil in limestone. (Photo: Matt Herod)

Trilobites (Source: Wikimedia Commons)

Cheers and thanks for reading!

Matt

Geology Photo of the Week #4 - Sept 16-27

This edition of photo of the week is of some pretty special rocks...in fact you might even say they are remarkable. Pardon the pun, but the focus of the pictures this week is the Remarkable Rocks, located in Flinders Chase National Park on Kangaroo Island just of the coast of South Australia. The Chase, as it is referred to by island residents, is a phenomenal park. It has beautiful hiking, great wildlife, such as New Zealand fur seals and the rocks. 

The rocks sit isolated atop a large granite outcrop next to the ocean. They are a gorgeous example of the incredible erosive power that wind, sea spray and water have on a landscape. The odd cavities and shapes are formed by these forces. The rock itself is 500 million year old Cambrian granite and weathering and erosive processes have formed these incredible sculptures over time. 

If you are ever in South Australia a trip to Kangaroo Island, the Chase and the Remarkable Rocks should be on your list!

My friend James posing under one of the odd overhangs. 

So damn cool!!!

Me sitting on one of the rocks

Thanks for reading! Has anyone else got good examples of "remarkable rocks"?

Matt

Geology Photo(s) of the Week 3 - Sept 9-15

This edition of "Photo of the week" is of something a bit closer to home than previous editions have been. The pictures below, excluding the sunset, were taken by me while I was TA'ing a first year geology field trip to Gatineau Park, just outside of Ottawa. The river in the distance in the photos is the Ottawa River. Of course, these photos have a geological interest as well: they show a great view of the Ottawa-Bonnechere graben. For any non-geo types reading this post a graben is the same as a rift valley.

In the Mesozoic a rift system started to open in the Ottawa area. However, this rift did not fully separate and no new continent was formed. The ground between the rift dropped and this is called a graben. Notice the sudden change between the flat plain of the Ottawa river to the Gatineau hills. That is the edge of the graben. 

A look at the edge of the graben from Champlain Lookout in Gatineau Park.

Google Terrain image of the Ottawa-Bonnechere Graben. Note the hills on either side of the flat area. 

A nice view from Champlain lookout showing the Ottawa River. 

Sunset in Gatineau Park

Thanks for reading,

Matt

Geology Photo of the Week 2 - Sept 2-8, 2012

Welcome back to school everyone! I hope that you all had great long weekends as well as great summers and productive field seasons! 

This weeks photos were taken during my recent trip to Whitehorse to do field work. I was collecting water samples in the Wolf Creek watershed just outside of town. Wolf Creek flows past an old copper mining district and the Trans-Canada Trail passes right past the old open pit mines along what is know as the Copper Haul Road. The trail is littered with boulders and rocks like the one below, which came from the mines and are heavily discoloured by copper minerals. I can't confirm the mineralogy on these ones but I suspect that it is a combination of malachite and chrysocolla. The blue box on the top of the rock is my conductivity meter for scale.

A large boulder absolutely full of copper alteration minerals.  (Photo: Matt Herod)

A close up of some of the discolouration by copper minerals. Pretty sure that is is malachite and maybe some chrysocolla. (Photo: Matt Herod)

Copper was discovered in Whitehorse by miners/prospectors on their way to Dawson City during the gold rush. The first claim was staked in 1897 and numerous others were staked in the following years, some by Sam Magee, of poetry fame. Mining of the claims began and was the first industry that the town of Whitehorse was built around. The early mining days continued until 1920 and ~150,000 tonnes of copper were extracted.

The development of better exploration techniques in modern times allowed for the discovery of additional copper reserves and mining began again and ran from 1967-1982 with an additional 9.8 million tonnes of copper extracted as well as some silver and gold.

Thanks for reading and enjoy the first week back!

Matt

Geology Photo of the Week 1 - Aug 26-Sept 1, 2012

Hi everyone,

Every so often I come across some really cool stuff and like every other geo-blogger out there I immediately take a photo and then share it. When I first started blogging I started a geology photo of the week theme in which I would write a description of the picture. Unfortunately, I let this lapse for the past year and a half so it would be nice to re-start it. Obviously this initiative is nothing unusual as many other geo-blogs already post a "Photo of the Week" sort of feature.  However, I hope that I can also contribute to the growing body of geology photos on the web by also posting every photo on ImageGeo the open access geology photo repository that the European Geosciences Union operates. 

Sometimes the photo will be a picture of a mineral or fossil. Sometimes it will be scenic and sometimes it will be something in the lab. So stay tuned since who knows what it will be? All photos will also be accompanied by a brief description explaining the geological significance and/or the location of the photo. 

To begin....

(Photo: Matt Herod)

This photo was taken in May 2009 by me on a field trip to Dinosaur Provincial Park in Alberta. It is a dinosaur bone, likely belonging to a hadrosaur, in soft sediment that has been exposed by erosion and will soon fall out of the small hoodoo that it resides in. You can see that half of it has already done so. Forgive the absence of scale, but the fossil was too high up for me to get a knife/pen/coin up there.

Dinosaur Provincial Park is one of the most incredible geological places that I have ever been. I don't want to write a super long post here but it is known around the world as one world's richest dinosaur bone sites. This was due to its fortuitous location and climate conditions during the Cretaceous period. It was a sub-tropical paradise full of rivers that deposited thick sand beds in which the bones are found today. Then, 10,000 years ago the continental glaciers covering Canada receded, exposing the sandy area to erosion, leading the formation of the beautifully carved badlands.  

The badlands. (Photo: Matt Herod)

Hope you enjoyed the first "photo of the week" and will come back for more down the road.

Matt  

Field Work Photos 2012

I am writing this post from the Vancouver Airport on my way back to Ottawa from Whitehorse where I was conducting my field work this summer. For now I'll just post some of the coolest pictures that I took. I'll write something more substantive on what we were doing there in a little while...at least after I have dried out my tent.

Our first stop once we arrived in Whitehorse was to the Yukon Archaeological Survey, who are kind enough to store our camping supplies for us when we aren't using them. A visit to the survey is always a cool experience since every ancient bone and artifact found in the territory is housed there. 

Mammoth leg bone.

They have quite a large collection of bones at the survey. It seems as though every square inch of the place as something cool in it. 

Gold rush era grave marker

Another gold rush era grave marker. Unfortunately the name is not legible. 

 Once we have picked up the gear it is time to head to the field. This year we were working the in Whitehorse area so we were able to camp near town and commute to the field every morning...super convenient!! In order to access our field area, which was located about 20 minutes south of Whitehorse, we would drive ATV's along the trails that cut through the watershed and collect samples from any creeks or springs that we came across. The trails in the watershed were a little rough and bumpy, but that just makes for fun ATVing and on the whole we were able to get around excellently, and did not get stuck once, despite some sketchy trail conditions in places.

The difficult driving conditions were well worth it though for the views of the watershed from the top of the mountains!

Golden Horn Mountain

View of Coal Lake and Coal Ridge

Granger Mountain and the permanent snowpatch that is always there.

On the shore of Coal Lake

Since we were driving around on the noisiest vehicles ever invented (ATV's) we did not see much in the way of wildlife.  I think this was for the best since we really did not feel like having to deal with bear troubles. However, we did see a few signs of life and even a few critters during the week to ensure us that the area was not completely devoid of animal life.

A marmot just chillin'

Wolf Creek deserves its name....this is a very fresh wolf track

I startled a caribou!

The caribou leaving. It is amazing how easily they can move over the terrain.

Thanks for reading.

Matt

P.S. This post is a bit of a milestone in that it marks the 50th published post on my blog!! Thanks to those who subscribe and read my posts. I appreciate your support. Here's to 50 more!!

The 1st Geolympiad

There have been lots of post in the science blogosphere about all of the interesting scientific aspects of the London games. Thus, on the eve of the Opening Ceremonies I have decided to hop on the Olympic bandwagon as well and write my own Olympic themed post.

Google Images

Imagine a world that was inhabited only by geologists. Not what I would call a pretty sight necessarily, however that is the only conceivable place that such an event as the following Geolympiad could occur. The overall ideals of the Olympics remain the same as the ones we all know and love. Although, I imagine there would be more beer around than there is in the athletes village...and maybe equal amounts of debauchery from what I've heard about the athletes village.

Here is what I think the games of the 1st Geolympiad would look like if they incorporated a geology theme into all of the events.

Events:

Mineral Identification: Pretty self explanatory. Fastest identification of 50 minerals. Points deducted for incorrect answers. Points added for chemical formulas.

?????? (Canadian Museum of Nature)

Fossil Identification: Same deal as the mineral ID. Fastest wins. Must be identified to genus and species level. 

??????? (www.fossilmusuem.net)

Rock Identification: Again, fastest wins. 

?????? (www.geology.com)

Mapping: Each competitor is given an area to map. There are medals for the fastest map to have all the basic criteria as well as for the most detailed and accurate map when compared to an already drawn map of the area by the judges. 

Rock hammer throw:  You all know that you have tried this event out in the seclusion of the woods, or competed with friends on one of the those down moments in the field. This event just adds a competitive edge to what is already a sport. I envision three main events: hammer throw for distance, accuracy and at skeet. Just imagine lining up with your hammer in its holster, yelling pull, and then whipping it out and taking out a clay pigeon in a cloud of shrapnel as it whizzes past. Sounds like fun to me!

Track events: The track events would be basically the same as the track events of the real Olympics but with one major caveat: all the competitors must be wearing full field kit and carrying a backpack full of samples. This means boots, vest, hammer, hand lens...the whole deal. I'd like to see Usain Bolt do the 100m with 30kg of rock on his back! He would still destroy everyone, but it would be fun to watch.

Navigation/orienteering: This is kind of already a sport, but it has yet to be included in the Olympics and it  would definitely appeal to geologists. Drop the the competitors off with nothing but a compass, map and their rock hammer and see how long it takes for them to get home. However, if this was done in a geologically interesting area they may never make it having banded together to take samples and characterize the geology.

River crossing: Take the competitors to a large river and make them get across without losing their samples. Sounds easy...how many would try and swim weighted down by all those rocks? This is a test of field smarts since this can be necessary in the pursuit of field work. 


Hammer fighting: Not too sure about how this would go down. I could see it getting a bit ugly. However, the regular Olympics have a lot of combat sports so the Geolympics need some fighting too!

(Photo: Matt Herod)

Rock breaking: I realise that this does not sound like much of an event, however it takes real skill to trim a rock in the field. For example, if you are out collecting and find something in a boulder it has to be removed and trimmed to make it possible to carry out. The way I see this event unfolding is that each competitor is given a boulder containing a sample they need to extract. Points for fastest and best job, points deducted for damaging the sample. 


Lava bomb deadlift: This is a pretty obvious one. It is pretty much weightlifting with large rocks. Maybe some throwing too?

Raaagghhh (www.trekearth.com)

Pebble skipping: This one is for fans and Olympians alike!! Medals awarded for distance and most skips. 


The DODECATHALON: All of the above!!!!!!!!!!!! Dodeca is 12 in Greek. 


So there you have the events of the 1st Geolympiad. Might be fun to put it on sometime?? I think I can see the IOC getting in on the fun provided we ensure that there are no doping violations or occurrences of hammer weighting.

Please feel free to suggest any events that you would like to see added to the Geolympics! Also, I have intentionally left the three pictures above un-identified so if you would like to qualify for the inaugural Geolympiad post the answers below.

Enjoy the games!!!

Matt

Field Work Tips

Preparing for field work marks a special time of year to the geologist. It heralds the upcoming field season/trip and the culmination of months or weeks of preparation. In fact, the trip itself is the least important part of field work. The work and preparation leading up is what makes a field trip go great or go horribly wrong. If you prepare carefully and meticulously for the field it has a much better chance of being successful. However, if you wait until the last minute to prepare, or fail to anticipate possible problems...well, the results will speak for themselves. I am in the midst of planning my field work for this summer. I leave in 2 days for Whitehorse, Yukon. It is a short trip this year, but that just makes it more integral that no time is wasted so everything gets done, and done right!

Clearly Charlie Brown and the gang did not prepare for this rainstorm....(Peanuts by Charles Schulz)(www.sln.org.uk)

I think the first tenet of field work that every geologist, biologist, oceanographer, etc. has to accept is that there is no such thing as a perfect field trip/season. Something will always go wrong! I know that this seems pessimistic, but my experience over the years is that something will always mess up. It doesn't matter if it is a large or a small thing, it will happen, and the only thing anyone can do is to try to anticipate these problems and come up with some solutions for them in advance. Of course, despite all of the planning you do something you did not account for will happen to throw a wrench in things so it is important to realize that you will be improvising solutions as the trip progresses. Things like weather or occurrences that are just out of your control, such as a closed ferry, cannot be prepared for. The only solution for acts of random deities is to just roll with the punches and take advantage of the times when things are going well. Finally, each field area is different and will present different challenges. Try and learn as much as you can about the area you are going in advance and plan based on that knowledge. 

My field area for this summer. All of my sample sites have been mapped and added into a GPS as well as all possible trails within the watershed. Hopefully this will make getting around and sampling much easier. 

The second tenet of field work is: you can only learn how to prepare by making mistakes or watching others.   It is sad, but true. We have all made mistakes in our preparations such as not accounting for something going wrong or forgetting an important piece of equipment. The only thing one can do is try not to repeat the mistake or the mistakes others make around you. We are all learning as we go so it is just faster to try and learn from each other. For example, one of my more costly mistakes was taking the lab pH electrode into the field. Lab pH electrodes are not hardy, durable items. They are precise, but they are not made to stand up to the rigours of field work. Unsurprisingly, the lab pH electrode broke. Luckily, we had planned ahead and had a back-up, but this mistake was easily preventable and we wasted a lot of money, since this item was worth over 300 dollars. I now know the difference between these pieces of equipment and will never make this mistake again! 

Oops! Notice the cracks and chips along the bottom. (Photo: Ian Clark)

So far I have spouted lots of doom and gloom and it is easy to get discouraged and adopt a bad attitude towards field work, especially when things go badly. Obviously this is the last thing you should do since the only way to solve problems is to remain clear headed and positive. This leads me to my third and final tenet of field work: have fun. Field work is fun, so enjoy it. Getting outside and going cool places in order to further scientific knowledge is a pretty rare opportunity that very few people get to experience, so don't waste it by getting depressed. The only way to be successful at field work and rise above its trials, learn from them and enjoy being out there!

Me enjoying some permafrost drilling by a retrogressive thaw slump in Fort McPherson, NWT.  (Photo: Laura Malone)

Have a safe and happy field season. I know I will!!

Matt

The Accretionary Wedge #48 - Atomic Geology

This month the Accretionary Wedge is being hosted by Charles Carrigan at Earth-like Planet. It is the 48th edition of AW and the topic is "Geoscience and Technology". The technology used by geoscientists has matured over the centuries. It began simply, with compasses, maps, sketchpads and pencils. However, now it has entered into a digital world in which geology is practised with satellites, lasers and instruments with all sorts of fancy sounding acronyms such as ICP-MS, LA-ICP-MS, , IRMS, SEM, TIMS, SHRIMP and a host of others. The use of the simple tools is not forgotten, and is still taught to every geology undergrad, however, at the last conference I went to people spoke a lot more about the odd acronyms above than the latest compass advances.

As much I enjoy getting out in the field with my compass, most of my work involves using machines with funny acronyms. The coolest of these machines, in my opinion is the accelerator mass spectrometer or AMS.

What is an AMS?

This is part of the 3 million volt accelerator mass spectrometer at the University of Toronto IsoTrace lab. I analyse my samples on this machine. (Photo: Matt Herod)

I like to think of an AMS as a mass spectrometer on steroids. Most mass specs these days can fit on a table. However, AMS is the beast of the class coming in at about 25m long and requiring a large room outfitted with at least a 10 tonne lift built into the ceiling. The smallest AMS that I have ever seen fits into a room about 15m x 15m, most are much larger.

A typical mass spectrometer. This is one of the newer models of Agilent ICP-MS's. Computer and keyboard for scale. (www.agilent.com)

For anyone not familar with mass spectrometry the principle is relatively straight forward. The sample is placed into the machine and is ionized. The charged atoms are then acceleration from the ion source and bent by a magnet. Once they have been deflected by the magnet they enter a detector where it is counted and then translated into usable data. The key part of mass spectrometry is the deflection of the ion by the magnet.  The deflection of the particles is based on the mass difference between isotopes of the elements in question. For example, if I want to analyze a water sample for oxygen isotopes I would have to deal with three main isotopes of oxygen: oxygen-18, oxygen-17 and oxygen 16, named thus because that is how much they all weigh. This weight difference is caused by differing numbers of neutrons in the nucleus of each oxygen isotope. e.g. 18O has one more neutron than 17O. This weight difference is what causes the deflection by the magnet as the ion flies by. Oxygen 18 is heaviest so it gets bent the least whereas oxygen 16 is lightest so it gets bent the most. We then set up a detector and can detect how much of each isotope there is. 

Basic mass spectrometry diagram illustrating the principle of mass separation by an electromagnet. (www.physics.utoronto.ca/~istotrace)

In principle AMS is very similar to this although it has a few more steps...

The first part of an AMS machine, as with any mass spec is the ion source. The sample is prepared in the lab and then the "target" is loaded into the ion source. AMS systems use a cesium ion source that is essentially a large gun that fires cesium ions at the target. Some of these cesium ions collide with the target, knock atoms of the sample off and ionize them. The ionized sample ions then fly out of the ion source and are then bent by an electromagnet. This removes some unwanted atoms. The ions are then enter the high voltage particle accelerator which contains a tube full of gas that pulls electrons off the ions and breaks apart molecules that could interfere with the detection. The, now positively charge ions, leave the accelerator and are then bent by another magnet into the high sensitivity detectors.

Schematic of the AMS machine at IsoTrace in Toronto. This diagram is representative of all AMS systems. (www.physics.utoronto.ca/~istotrace)

The sample holder where the targets go.  (Photo: M. Herod)

The 3 million volt accelerator with the stripper canal inside. The flight tube is entering on the left and is all negatively charged.  (Photo: M. Herod)

Flight tube coming out of the accelerator. Everything is positively charged on this side.  (Photo: M. Herod)

Ion source  (Photo: M. Herod)

Flight tube with the rare isotope detector at the end. (Photo: M. Herod)

What is it used for?


AMS has a wide variety of applications in many fields of science. The primary one is the measurement of carbon-14, which is usually used for carbon dating. However, AMS has a wide variety of applications making it an extremely useful instrument in the geologist's arsenal. Up until recently most AMS machines were located in university physics departments and were used almost exclusively for particle physics research. Recently most physicists have lost interest in AMS's and the machines are starting to end up in geology departments around the world. This is opening new doors in applied AMS research and is turning decades old technology into a cutting edge field.

The reason that AMS is different and useful when so many other smaller, and cheaper mass spectrometry systems exist (a new AMS is ~7-8 million dollars) is that it allows for the analysis of rare isotopes that other systems cannot detect due to interferences from other elements. It also allows us to measure much smaller quantities than any other method and allows for the analysis of radioisotopes that cannot be detected using other methods such as decay counting.

Some of the major isotopes that most AMS machines around the world analyse for are: carbon-14, beryllium-10, aluminum-26, chlorine-36, calcium-41, iodine-129 and isotopes of uranium and plutonium. I'll talk about the uses of some of the major ones.

Beryllium-10 and aluminum-26 are isotopes that are used in the field of exposure age dating. Basically, when cosmic rays interact with the mineral quartz they produce 10Be and 26Al. The amount of each isotope and the amount of its radioactive decay products can tell us how long a rock has been exposed at the surface of the Earth. This is useful for estimating erosion rates, dating glacial events, dating landslides, and other stuff like that.

Carbon-14, the dating isotope. Everyone has heard about 14C dating. Basically anything on Earth that contains carbon has some radioactive carbon-14 as well. This means that we can date anything that contains carbon, but only if it less than 50,000 years. However, that encompasses almost all of human history so a lot of really interesting things can be dated this way. Everything from ancient trees and bones to picture frames and historical artifacts can all be dated with 14C. One way to measure 14C is decay counting in which the beta particles coming off the sample are counted and then dated, however, AMS provides a much faster and more sensitive way to detect 14C. This has made it the method of choice for anyone doing carbon dating.

Iodine-129, I could write a whole thesis about this one...oh wait. I'll just give the highlights. 129I has a long half life and is produced naturally and by human nuclear activities. Nuclear fuel reprocessing and nuclear bomb testing are the two major sources, but nuclear accidents such as Fukushima, Tomsk-7, etc. have contributed lots to the environment. The reason that we/I study is that understanding its movement in the environment is crucial for the future storage of nuclear waste. Therefore, we need to establish current levels, determine how it travels, and where it comes from. Also, as an emerging contaminant it is not a health risk yet, however, if concentrations continue to increase it could become worth regulating. AMS is the only way to analyse for 129I reliably at the moment.

Finally, the newest advances in applied AMS detection are to analyse for uranium and plutonium isotopes. These are such heavy and rare elements that it has always been problematic to analyse for them. However, new techniques are making it possible to detect Pu and U. This has applications in the burgeoning field of nuclear forensics. Basically, say a terrorist organization were to get its hands on some enriched uranium. It is very difficult to tell where the got it from, however, if the isotopic signature of the material can be ascertained it makes it much easier for investigators to determine where it came from.

To sum up I have explained only one small part of the rapidly growing intersection between geology and technology, however, I hope that you now have more of an appreciation for AMS technology and the powerful tool that it can be to solve real world problems. If you have any questions or comments please add them below.

Thanks for reading,

Matt

References:

Ragnar Hellborg and Goran Skog (2008). Accelerator Mass Spectrometry Mass Spectrometry Reviews (27), 398-427 DOI: 10.1002/mas.20172

IsoTrace Laboratory: http://www.physics.utoronto.ca/~isotrace/

PRIME Lab: http://www.physics.purdue.edu/primelab/