EGU Blogs

Photo of the Week

Geology Photo of the Week #34

June 3, 2013

My apologies for the slight blogging hiatus over the last little while. I have been preparing for a conference and then attending and so I had to put blogging on the back seat for a few weeks to prepare properly. However, the conference is done, my talk is given so now I can get back to blogging…at least until the next one…which starts on Tuesday (tomorrow). Luckily, I get to just watch at this one and don’t have to go through the effort of actually preparing to say anything. This conference is a very focused and small event that specifically concerns the geoscience of the proposed low-level radioactive waste storage facility in the Bruce Peninsula.

The photo for this week is known simply as the “The Candelabra”. It is one of the best if not the best specimen of blue-cap tourmaline in existence.

Blue cap elbaite at the Smisthonian Museum in Washington D.C. (Photo: Matt Herod)

Of course, the Canadian Museum of Nature has a pretty nice one also:

Blue cap at the Canadian Museum of Nature (Photo: Matt Herod)

Both of these unbelievable specimens come from the same location, which is the Tourmaline Queen Mine in Pala, California. The mine is still a producing gem mine to this day and if you would like to find out about its colourful history click the link above (pun intended). The geology of the mine is no less fascinating than the crystals it produces. It is located in a pegmatite, which is a class of igneous rock that can often be a source of large crystals and/or unusual mineralogy. Pegamatites are a type of intrusive igneous rock that can form from a melt that contains a high percentage of volatiles, such as water, which lowers the viscosity of the melt and allows for the formation of large crystals compared to those formed from a higher viscosity melt. Some crystals can be several metres in length. Furthermore, pegmatites can often contain a high concentration of incompatible elements such as lithium, tungsten and boron. These elements, among others, don’t normally form minerals easily, and are known as lithophiles or incompatible elements. When they are forced to crystallize in a pegmatite that has branched off a large batholith the result can often be unusual minerals such as toumaline or spodumene.

The reason that the tourmalines from the Tourmaline Queen have the “blue cap” is because of their chemistry. In the case of the blue caps there is a sudden shift from manganese rich to iron rich, which causes the sudden change in colour.

Thanks for reading,

Matt

p.s. This post represents something of a milestone for this blog as it is my 50th post since this blog began in October 2012. I am looking forward to another 50!

Geology Photo of the Week #33

May 13, 2013

The photo of the week this week is of a very special place in Canada. Yes, predictably, it is the Yukon. However, this part of the Yukon is unique. It is a special region known as Beringia, which extends into Alaska and Siberia and it is the only part of Canada that was not covered by kilometers of ice during the last glaciation. Beringia is a special place because it is believed that that first human inhabitants of North America made their way across the exposed land bridge form Siberia into the Yukon and spread west and south. Geologically, Berinia is interesting as it is full of Pleistocene mammal fossils like mammoths, short faced bears, giant beavers and other giant mammals. It is also strange because of the degree of weathering and erosion that the rocks have undergone is like nowhere else in Canada. Piles of talus may not seem like a big deal to people from other parts of the world, but for a Canadian geologist this is a somewhat unusual sight as most of our mountains had a good scraping 20,000 years ago and we just don’t see this level of weathering anywhere else in the country.

Cheers,

Matt

Geology Photo of the Week #32 – Name that squid!

May 6, 2013

This edition of the photo of the week highlights another piece from my personal collection.

Cephalopod – Matt Herod Collection (Photo: Matt Herod)

This is a cephalopod. More specifically it is a member of the Order Endocerida and the Family Endoceratidae. This creature, which hopefully you can see was pretty large (golf tee for scale) was the largest of the Ordovician cephalopods found in Ontario and this is a particularly fine/large example mainly because it tapers all the way to the apex at the end, which is a very rare find, and because of its large size (~7ocm). Cepahlopods, such as Endoceras, were the top predators of the Ordovician ocean that once covered most of southern Ontario and they grew up to several metres long. The cephalopods of the past resembled modern squids of today. Indeed, they were the progenitors of the Cretaceous ammonites and the squid and octopi of today’s oceans. If you enjoy calamari, thank a cephalopod!

(Photo: Matt Herod)

This zoomed in look at the cephalopod shows the siphuncle and the suture lines, which divide the inner chambers. The siphuncle was an inner tube that ran the length of the cephalopod and allowed it to control its buoyancy. The fact that the siphucle and sutures are clearly preserved is a great feature of this cephalopod, however, there is more….

When I was extracting this fellow from the giant boulder he was in I was unfortunate enough to break him in several pieces, which I have now super-glued together. But why, you may ask, did I not super-glue him completely together? The answer is pictured below.

(Photo: Matt Herod)

One of the points at which he broke contained this tiny little trilobite, which I am pretty sure is a Bumastus, based on the shape of its pygidium (tail). I decided not to rejoin the parts together so that we could still see this little dude that made this find a 2 for 1 deal. The obvious question is what is this little guy doing in a cephalopod? Was he eaten? Was he seeking shelter? Was he eating the already dead cephalopod? I have no idea, and it is pretty hard to prove one way or the other now. Please weigh in and let me know how you think he got in there!

Also, the other great fossil in my collection, the two trilobites that were featured in the Photo of the Week #25 and are named “Bert and Ernie”. We have a similar pair here, but they lack the awesome name. Please suggest your favourite names for this odd couple.

Cheers,

Matt

Geology Photo of the Week #31/Science Travels

April 29, 2013

Sorry for the brief hiatus from blogging. This past week I was in Kenora and Dryden, Ontario getting into some great science outreach with an organization from uOttawa called Science Travels. Science Travels is a science outreach organization that sends science graduate students from the University of Ottawa and Carleton to northern communities to give presentations about a variety of science topics. This was my second Science Travels trip and it was a great one. I was teamed up with a neuroscientist, a chemist and a molecular biologist and together we gave talks on DNA, invasive species, the brain, chemistry, digestion, ecology and of course, geology! Throughout the week we presented 8 times per day and in total to well over 500 students. We were also lucky enough to present at three first nations reserves and it was a great experience to learn about first nations culture and present some science in some more isolated communities. It was a tiring week, but there is nothing better than than the feeling that the four of us may have gotten some kids interested in science or opened the door to a career that may not have been considered before.

Here is a map showing where we were. Kenora is the largest community nearby and has approximately 15,000 residents.

Click for larger image.

 

The photos for this week were kindly donated by my colleague Erin Adlakha from the University of Ottawa. They are some nice zoomed in microphotographs (XPL and PPL) of magnesiofoitite (alkali-deficient dravite) replacing dravite in basement metapelite below the Athabasca Basin.

Magnesiofoitite in XPL (Photo: Erin Adlakha)

Magnesiofoitite in PPL (Photo: Erin Adlakha)

Pretty amazing pics. I am trying to convince Erin to supply me with a few more so stay tuned for some more great photos from the Athabasca Basin.

Cheers,

Matt