BC Volcanology 101: Mount Meager, Part 2: Dams!

A conclusion to this trip with the GSA is long overdue - bear with me, as several university courses as well as work have been taking up most of my time these days!

On Sunday I had the pleasure of giving a talk to the Vancouver Island Paleontology Society in Qualicum Beach, BC. The title suggested by Dr. Graham Beard was "Everything You Wanted to Know About Eruptions, But Were Afraid to Ask" aka "BC Volcanism". It was such a pleasure to present to such an enthusiastic, wonderful group of people I've known for several years, as well as the public and several local geologists, and to dispel some common myths regarding volcanoes in British Columbia and the Northwestern USA. 

Most of the talk, however, covered the GSA trip I took in October 2014, so with this post, I aim to conclude the tale of Mount Meager's 2360 BP eruption, and then I can settle into the homework that no doubt will consume me until the year is out.

But here we go! Get ready for one hell of a dam, more columns (NOT in basalt this time...) and the Meager Creek Landslide of 2010.

Our "view" (sigh) of Mount Meager near Keyhole Falls, morning of Day 3.

First stop on this day was at Keyhole Falls, the scene of a large lava dam that was created during the effusive stage of the 2360 BP eruption. The falls gets their name from the canyon shape through which it flows, shaped at the falls just like an old-fashioned keyhole, which then opens up to allow the Lillooet River a chance to meander along the base of Mount Meager. Below is a picture of the falls from an angle we didn't get to see, followed by a photo of our view of the canyon below:

Upstream view of Keyhole Falls. We were positioned at the top right of the cliff in the trees, directly above the falls. Photo credit The Wilderness Committee, 2009.

At about 14 days after the initial eruption, as our welded block and ash flow continued to be deposited in the valley below, a lava dam across what is now the Lillooet River began to form. The dam would eventually reach >1000m in thickness, and was capped by a non-welded version of the block and ash flow deposit. 

This dam created has been termed paleo-"Salal Lake", given that present day Salal Creek now flows into this ancient lake bed. The evidence for Salal Lake is given in both the underlying river sediment deposits that have been covered by the pyroclastic flows and by layers of volcaniclastic sediment washed downhill into it after it's formation.

After the initial creation of the dam, volcanism slowly continued, waned, and then resumed, adding layers to the top of the dam, and keeping the river at bay. The nature of this deposit, although being welded to some degree due to heat, was not enough to hold the river back for very long, and within a month, the dam failed catastrophically, creating a downstream debris torrent that washed out the canyon. 

Keyhole Falls, facing downriver, from the cliff directly above the 'keyhole'.

Which leaves us with the canyon today, plus about 2300 years of fluvial erosion. 

It should be noted that the EXACT nature of the deposit forming the dam is not firmly known, due to the deposits inaccessibility within the steep canyon. Dr. Andrews is looking for a sucker... I mean brave grad student, who would be willing to rappel over the edge and get a good look at these deposits...any takers??

One of our final stops, and perhaps the most interesting to me, was an outcrop along the road further downstream from Keyhole Falls which showed columns forming within the block and ash flows. This was the first time I'd ever seen columns in something other than the basalt, and I was overwhelmed and FULL of questions!

In the following photographs, you can see the edge of the flow as it reached a cooling surface. Note the small columns on the right hand-side of the deposit that grow into larger columns toward the left of the deposit, and enjoy:

Dave (UK - left) and Graham (USA - right) investigate the outcrop. The flat cooling edge is to the right of the outcrop, just above Graham's head, with small columns. As you go to the left in this photo, you will see progressively larger columns forming. 

Dave at the cooling edge of the outcrop. Here you can really see the formation of the columns! The columns here are mm-cm in scale, growing to 0.5m and larger in diameter as they move further from the cooling edge.

My biggest question here, while everyone else was preoccupied with the other, likely-more-important-science, was why is the cooling edge SO FLAT? When I got up the courage to ask the team about this, a lot of ideas were thrown around, before Graham eventually said: "Well, I don't have a firm answer for you: but that could make a great thesis!"

Our final stop was at the campsite along the Lillooet River, which, in 2010, avoided destruction by mere metres when an estimated 40,000,000 cubic metres of debris rushed down from Capricorn Mountain (the peak adjacent to the east of Meager). This landslide was deemed a lahar, and is known as the second largest landslide in Canadian History. It also created yet another dam along the Lillooet River, which remained only a matter of days before becoming washed out and sending even more debris further downstream at an astonishing rate. 

That's me - for scale! View facing towards Mount Meager/Capricorn Mountain and the Meager Creek Valley. Photo credit Dr. Dave MacGarvie, 2014.

The UBC EOS van faces the campsite, in the break in the trees, that escaped washout by meters!! Landslide deposit can be see in the background.

In British Columbia, the most frequent hazard related to volcanic activity ends up, indirectly, being landslides and slope instability in general. When working with Dr. John Clague from SFU on a seismic hazards project for my undergraduate thesis, he mentioned that, if I had aspirations to become a volcanologist, I should be prepared to work in more of a geo-engineering capacity if I wanted to stay in BC. And it's true, the better one understands how the geology is put together, the better you know how it's likely to fall apart. I won't get into anything such as funding for Canadian scientists here (or should I say, extreme lack of funding... ahem), suffice it to say that although we don't necessarily need to monitor volcanic activity in southwestern BC, we should be paying closer attention to the landforms around us in order to stay safe. 

ANYWAYS

Thus concluded our fabulous tour of Mount Meager! Now, all that was left, was to get a damn picture with the iconic peak!! On our way back, we stopped in the flat fields adjacent to the Lillooet River, and, waiting for the last of our team to join us for the drive back to Vancouver, we were rewarded with only a few precious minutes for a photo op - for the first time during this entire trip! Here is my only portrait with Meager:

At last! A view of the peak in the final moments of the trip! 

And so, with my dream of becoming a volcanologist at once more clear in my head, and more intimidating than ever to achieve, I sat in silence on the drive back to the ferry. The crew kindly dropped me off, and while waiting for the boat home to my 'rock' (Vancouver Island), I sat and had dinner at The Boathouse Restuarant in Horseshoe Bay, sipped a well-deserved drink, reviewed my maps and notes, and felt more inspired than ever. 

Thank you for reading :) Keep in touch for preparations (2014) for adventures (2015) to Mount Edziza and Mount Garibaldi! Until next time!

BC Volcanology 101 - Mount Meager, Part 1

2360 years ago, Mount Meager, just north of Pemberton, BC, and part of the Garibaldi Volcanic Belt in the Cascade Volcanic Arc, created the province's largest Holecene volcanic eruption, as well as two of the coolest outcrops I've ever seen. 

This post continues the GSA 2014 Field Trip through the southern portion of the Canadian Cascade Volcanics. For the entire trip, until the final hour of our time in Pemberton, the clouds kept all of us from seeing even a flash of the jagged peaks... resulting in many jokes about the "meager view" we got each day (harhar) ;)

Our consolation, however, was some amazing outcrops of pumice and pyroclastic flows. What follows here are details from Day Two, and the explosive phase of the most recent eruption.

Here's the lowdown on the 2360 BP eruption:

• The Bridge River Vent, lying in Plinth Peak in the Mount Meager Massif, and the youngest vent from this complex, is responsible for releasing these materials.
  
• The eruption sent a 20km high Pilian column into the air - evidence of this stretches as far East as Alberta, the neighboring province, about 530km away.
  
• The first explosive phase (detailed in this post) resulted large pumice deposits and pyroclastic flows, including a welded block and ash flow.
  
• The second, effusive phase involved a lava flow that dammed the Lilloeet River, creating a lake up-river from present day Keyhole Falls (details in the next post to be posted!).

First stop: the pumice pit.

Happy as geologists at a pumice outcrop! Wait...

After a short briefing at our first stop, our guides let us loose to explore the outcrop with an assignment (usually given to the UBC undergraduates) to collect as many different types of rocks as we could find. We would then recap and talk about why there were such a wide range of samples here...

...Half an hour later, there were 12 geologists still rummaging and pocketing various samples, ooh'ing and ahhh-ing over their finds, with only 3 representative samples on display. Dr. Russell was not impressed, but managed to kick us into gear and discuss what we found.

Firstly, think of pumice as the frothy, extremely hot lava bubbling away at the top of the vent. As it gets ejected from the vent, it cools quickly, with the end result being a light, ragged form of volcanic glass. Highly vesicular, it can easily get airborne - this outcrop, as well as the open pit mine in the following photos, is within 5km of the vent.

Dave for scale - showing the pumice outcrop. Note the band running through the centre l-r, which indicates a slower phase or "easing" of the explosive eruption (made up of finer particles) and the various holes in the pumice, which where once filled with tree branches.

Pumice in hand sample - the color changes may indicate differentiating in cooling rates, although this requires more investigation on my part.

"View" of Mount Meager and the Bridge River Vent from the open pit pumice mine, ~ 70km north of Pemberton, BC. See http://garibaldipumice.com/ for more information on this specific location.

Our next stop was one of the most amazing outcrops I've seen (next to the folded limestone on Quadra Island, which will be detailed in a future post). It was a welded block and ash flow, representing a violent pyroclastic flow that tore away chunks of the peak as it erupted, and is seen here overlain by the effusive phase (lava flows). 

Enjoy the following pictures, that do not do this outcrop justice...but try.

The group at the base of the welded block and ash flow outcrop, complete with waterfall in background!

Closer examination of the deposit. The light grey you are seeing here is the fine grained ash, and the black portions are chunks of the Plinth formation, which makes up the original country rock underlaying the vent.

Dr. Graham Andrews gives us the details about the events that lead to this formation. 

This was the first geologizing trip for my new boots - covered in volcanic ash seems a great way to start off our relationship!

Next up: The effusive phase of the 2360 BP eurption and the Meager Creek Landslide of 2010!

BC Volcanology 101 - Columnar Basalt

"Our volcanoes look like crap." 

-Dr. Kelly Russell (UBC), BC Magazine, Summer 2010.

       Having been born and raised in British Columbia and never having even considered the possibility that our province has a volcanic past until I began my degree in geology, I'm pretty inclined to agree with Dr. Russell on this point.

       Recently I got the opportunity to spend 3 days with some world-renowned volcanologists on a tour of the Canadian portion of the Cascade Volcanic arc (in particular the Garibaldi Volcanic Belt, or GVB) and it's formation during the Quaternary. The trip was put together by Dr. Graham Andrews of the California State University Bakersfield, and by Lucy Porrit and Dr. Kelly Russell himself, both from University of British Columbia. As a prelude to the Geological Society of America's annual meeting in Vancouver, the trip was one of many geologically-themed tours that anyone attending the conference could sign up for. Although expensive (but not one of the most expensive trips by far), this trip, for me was money well spent, indeed.

      Our trip began with an early morning meeting at the Vancouver Conference Centre, where I was introduced to fellow grad students from Canada and the USA, as well as our trip leaders and other enthusiastic participants!
      Our group also included a geoarcheologist, a planetary geologist, a veteren of the USGS in Hilo with his wife, a volcanologist from Japan who's English was limited, Professor Cathy Busby from UC Santa Barbara and Dr. Dave McGarvie from the Open University in Scotland - who I had been to see in the summer in Edinburgh to discuss various PhD projects in Iceland. Included in our crew was Dr. Volcano himself (aka Dougal Jerram): volcanologist and BBC presenter, he kept things light as we battled through torrential rain, delays, and various hiccups along the trip. After introductions, and an extra influx of caffeine, we loaded up our gear in the vans and headed of for volcanic rocks and a heck of a lot of BC rain!

       At our first stop en route to Pemberton along the Sea-to-Sky highway was at Porteau Cove, where we got the low-down on WHY our volcanoes in southwestern BC look like crap, exactly.
       First of all, to fill you in, BC is made up of several accreted geologic terranes that, due to many millions of year of subduction, have added themselves onto the ancient North American continent, creating the North American Cordillera - which itself ends approximately at the Rocky Mountains, and stretches northward creating the Yukon and portions of Alaska, and southward into the western United States.
       Quaternary volcanism in this region of BC is due to the subduction of the Juan de Fuca plate along the Cascadia Subduction Zone (CSZ), and the subduction that has taken place during the last 4 Ma is suggested to be responsible for uplift of the Coast and Insular Belts (terranes), including the GVB. There is evidence for a relatively hot seafloor being subducted: this creates a buoyant subducting plate and thus an uplift of the overlying continential column. As the GVB get's uplifting, mass wasting increases as erosion rates are accelerated, which, in short, gives this region it's "crappy" volcanic appearence - especially when related to Washington and California states beautiful, textbook stratovolcanoes (think Mount Baker, Mount Rainier, Mount Shasta, etc).

       The regional perspective of the geology now aside, and the rain beginning to set in, we were off to look at something that has fueled my desire to work in sub-glacial volcanology since I first saw it in the fall of 2012: Columnar Basalt. Our next stop was up along a forest service road west off the highway just past the Squamish Chief, and showed us the edge of the Mount Cayley volcanic field and the Tricouni lavas, which give evidence of lava-ice contact in the adjacent valley, and is demonstrated by spectacular radial columns (Fig. 1b). Kelly was determined that the rain would not shut us out, even though the weather was getting heavier by the minute, he busted out some magnets to attach geologic maps to the side of one of the UBC field vehicles (Fig 1a).

Figure 1a. Dr. Kelly Russell orients us at the Tricouni lavas,
with a spectacular slope of broken basalt columns in the background.

Figure 1b. Radial columns in the Tricouni
lavas, Dave McGarvie for scale (bottom left).

       We then continued northward along the highway and stopped to view spectacular road cuts that exposed some of the Cheakamus Valley lavas and a section of the basement rock (Fig 2a), which is highly metamorphosed. Although these flows show us beautiful columns (Fig. 2b), the vent or source of these lavas, as well as a basaltic dyke that may be a feeder dyke to this deposit, is not clear.

Figure 2a. Highly metamorphosed basement rock, overtop of which the Cheakamus lavas flowed.

Figure 2b. Dr. Volcano (Dougal Jerram, bottom right) for scale at
road cut, showing two flows with different column formation.

       Brandywine Falls (Fig. 3a) was our next stop, to investigate the outcrops along the BC Railway, and, of course, to oooh and ahh over the falls. Here, I also discovered what a hyaloclastite was, and why everyone had been talking about them on this trip! It was my first field-encounter with volcanic glass (Fig. 3b).

Figure 3a. Brandywine Falls, showing four different column layers.

Figure 3b. Hyaloclastite! A hydrated, tuff-like breccia that is found in subglacial eruptions, and full of volcanic glass (can you spot any of the black shards in these samples?)

      The last stop on day one was where I fell in love with columnar basalts, and I was excited to show Dave, my potential supervisor, exactly where I began my passion for subglacial volcanics. For you BC geologists, you've likely seen this site - the eastern portion of the abandoned Railway Quarry north of Squamish which, in the words of several volcanologists on our trip, is a "World-Class Outcrop". This portion of the Cheakamus Basalt lavas show all sorts of shapes of columns and change in size and orientation from the base of the outcrop to the top.
       In general, the joints of the columns form perpendicular to the flow. Columnar basalt and it's formation can get complicated and unclear very quickly, so please, enjoy the following photos (Fig 4a-e) instead of my attempt to deeply explain them here:

Figure 4a. Graham at an outcrop that demonstrates 'pinching' of columns toward the top of the flow.

Figure 4b - columns, galore!! 

Figure 4c - Columnar Basalt is always a hit with geologists!!

Figure 4d - Kelly, Dave, and Duncan (Lancaster University) examine column ends at an extraordinary outcrop.

Figure 4e - "World Class Outcrop" of columns! Apologizes for the lack of scale here... but isn't it cool??

Enough of Day One of our GSA trip - keep reading for more BC Volcanology in the posts to come, where we explore both the explosive AND effusive phase of the 2360BP Mount Meager eruption, as well as details on the massive Meager Creek Landslide from 2010.

In the Beginning...

"In the beginning God created the heavens and the earth. The earth was formless and void, and darkness was over the surface of the deep, and the Spirit of God was moving over the surface of the waters..." Genesis 1:1 -1:2

Now, if you've just read that and thought you're in the wrong place - think again. 

       To begin this blog with a biblical quote seems at once both profound and at the same time, hypocritical, however, for centuries of human history, this is how we devotedly believed out planet had formed. 

       This summer I experienced more geologic joy than I had ever felt. In my usual summer trip to work in Co. Kerry, Ireland, I made a pit-stop in Edinburgh to meet with my PhD supervisor at the Open University in Scotland. With only three days to tour Edinburgh horribly jet-lagged, and mourning the 3 month separation from my man in Canada, there was only one location I wanted to see:

Hutton's Section.

       Hiking up the Salisbury Crags in a rare Scottish heatwave on day two in Scotland, I walked right past, within meters, of the famous outcrop! So, on my final day in Edinburgh, in the very, early morning hours before my flight to Ireland, I made the pilgrimage up to the crags to see where James Hutton had so famously attempted to convince a pious crowd that indeed, the Earth was made molten.

Posing next to the outcrop that started it all...(For more information on the formation and why it was so important, please click here: http://www.geos.ed.ac.uk/undergraduate/field/holyrood/huttonsloc.html to access the summary from the Univeristy of Edinburgh's School of Geologic Sciences).

       I'll admit I was emotional, sitting there at the birthplace of modern geologic thinking. My time at university had mostly been spent (other than in the classroom/lab/doing homework) travelling the province of BC to present Vancouver Island University's "Awareness of Climate change through Education and Research" (ACER)'s presentation on "The Science of Climate Change" to high school science students (for more on this program at VIU, please take a look at my previous blog: http://acer2011.blogspot.ca/). High school students are at a developmental stage that, understandably, makes them more concerned with the present than the future, and it is very challenging to inspire in them concern for global issues that don't affect them directly. 

Ginny running a demo for ACER in during the group's 2011 province-wide road trip!

       This attitude I can easily understand: I was not the best high school student. In fact, I wanted nothing to do with it, and couldn't have cared any less about being in a science classroom. I barely graduated, and went years without going back to school. It wasn't until I sat in Sandra Johnstone's VIU classroom, taking geology as an elective, that I fell in love with geology. Madly in love. With years of teaching/coaching experience, I then grew passionate about teaching in geology, and got the opportunity to work with ACER for three wonderful years. I started to see how, if given facts that they could understand, and even observe, how you could get a student thinking critically and begin answering questions on their own.
       However the God-fearing adults that Hutton faced, set in their beliefs for hundreds of years, must have been substantially more difficult to convince that the Earth was created not by God, but by what we consider now to be fundamental planetary processes - particularly when all the evidence for how the Earth was formed and re-shapes itself was not available yet - no one had unearthed the clues yet (pun intended). In addition to this, Hutton was God-fearing himself, and was concerned that he would suffer for his apparent sin of questioning God's role in creating the planet. (He was also a terribly nervous public speaker, so that didn't help his case.)

       Sitting at the famed outcrop, I felt a kinship with Hutton. We both knew that ideas had to change - that the approach to science needed to be something fathomable, that you could SEE and OBSERVE in order to change someones mind, and that it was important to start thinking in a new way. 

View at 6:14AM on June 18th, 2014 of the Salisbury Crags from Arthur's Seat (volcano) overlooking Edinburgh. 

       Thus begins the exciting journey that I am on. Igneous Is Bliss is just a powerful thought at the moment, but the organization will be used to do one thing most of all: to inspire scientific thinking in the next generation, particularly in the geosciences. The title of this blog itself is a small play on words, in that we will aim to replace "ignorance" with a love for geology/science/critical thinking.
       As a future volcanologist, I aim to engage students about the geologic history of my beautiful home province of British Columbia in all it's volcanic glory. By following my own passion in volcanology and love for teaching, it is my hope that students in BC will become intrigued by the stunning geology around them, begin asking questions that they can answer on their own (with a little push towards how to "science"), and contribute to science in Canada, and the world, to solve the issues their generation will face. This can be done through a combination of field trips to awesome volcanic sites (ie: The Barrier in Garibaldi Provincial Park), guest lectures in high schools and universities and by contributing to science myself through graduate work. 

       In June 2014, when I stood where Hutton had stood so many years ago - when he KNEW then that he had the answer to the big questions about Earth's geologic upbringing - and tried his best to provide all the clues to people so they could see it, I, in turn, wanted so desperately to continue what he started, and what so many before me have done since.

Let the journey begin.