Northern Convergence: We'll Call it "Rock": The Okotok Erratic

There is a big rock out on the high prairie near Calgary, Alberta. That all by itself is a bit of strangeness. It's even more strange because it is around a hundred miles (160 km) from the cliff in which it originated, up in the Rocky Mountains in Jasper National Park. The Blackfoot Indians had a creative name for the rock, Okatok, which in their language means, um, "rock". These names always sound better in the original language! For whatever reason, the spelling changed a bit to Okotok.

The Blackfoot people had a great story for how the rock got to this spot, a myth that could have served as the inspiration for the rock monster in the movie "Galaxy Quest". Their legendary trickster Napi was resting on the rock on a hot day, so he left his cloak on the rock, saying "Here, I give you my robe, because you are poor and have let me rest on you. Keep it always". Murphy's Law dictates that it soon got cold, and the rain began, so Napi asked for the return of his robe. The rock refused so Napi grabbed "his" cloak. In a moment, the rock was up and running after him! Napi called on his animal friends, the Bison, Antelope and Deer, and none of them could stop the gigantic rock. When all seemed lost, a bat flew straight at the rock, collided with it, and the rock was split in two! The bat had saved Napi, and got a squashed face for all his trouble (such things have to be explained somehow...).*

A smaller erratic a few hundred yards from the Okotok Erratic

The geologists tell a different story, and were it not for the overwhelming evidence it would seem just as fantastical. During the Pleistocene Ice Ages, the continental ice sheets covered all of the region thousands of feet deep. Up in the Rockies at Jasper a huge rock slide dumped massive boulders onto the surface of the glaciers emanating from the high peaks. The glaciers flowed eastward onto the High Plains, eventually meeting up with the vast ice sheet that originated near Hudson Bay. The two ice sheets didn't mix, so the two "rivers" of ice flowed together towards the south. The gigantic rocks from the cliff in Jasper were dumped in a line many miles long where the glaciers moved together. These isolated boulders are called glacial erratics.

The rock is sometimes claimed as the largest erratic boulder in the world, but I have no way to evaluate the claim. It certainly is huge, and worthy of a visit (it is a few miles southwest of Calgary). The Blackfoot or other First Nation peoples were certainly impressed. Faint pictographs can still be seen on the flanks of the rock.

Pictographs are symbols painted on the rock. Petroglyphs are chipped into the rock.

This is a continuation of our Northern Convergence tour of British Columbia and Alberta. In this case, I guess "convergence" refers to the two masses of glacial ice. We concluded our visit and headed back towards the Rocky Mountains and Crowsnest Pass to check out a not-so-long-ago tragedy. More on that next time.

*The Blackfoot legend is  loosely rephrased from interpretive signs at the park.

Northern Convergence: Vancouver Island, the Plan That Was, Part II

Ah, the lost opportunities! I don't want to make it sound like we had a bad Northern Convergence trip; we actually had a great time taking our students through an exploration of the geology of Vancouver Island,  but the trip we made was different than the one we planned. In the last post we talked about the Sooke Potholes, and in today's post we are talking about the opportunity to understand why the basalt exists.

East Sooke Regional Park is a large wilderness park just 20 kilometers or so outside of Victoria at the south end of Vancouver Island. It has a nice network of trails that explore rocky coastlines and deep rainforests. I was really looking forward to exploring it, but time was conspiring against us. That opening picture? That's where the sun was in the western sky as we arrived in the park on our little scouting trip a few days before we were to meet the students. Sunsets take awhile at these northern latitudes, but there are still a finite number of hours of daylight, and we had used most of ours up.

I ran down the trail to Becher Bay because East Sooke Park is said to have marvelous exposures of the oceanic crust that had been pushed into the subduction complex along the western coast of North America, and lifted up above sea level. The ocean crust includes pillow basalts, which form as lava spills out on the ocean floor, sheet dikes, which were the conduits that fed the seafloor eruptions, and gabbro plutons, the magma chambers that fed the eruptions. These rock associations are called ophiolites, and they are often of great interest to geologists, not just for the knowledge they give us about oceanic processes, but because they often are a source of valuable ores, such as copper, mercury, chrome, and platinum.

I literally only had minutes, and didn't have time to walk to the petroglyphs, which would have offered exposures of all three kinds of rock, but I consoled myself by realizing I would be back in a few days with my students and more time. Which didn't happen, as it turned out (as I said, we saw great things, but we didn't make it to East Sooke). I looked at the beautiful small bay, snapped a few pictures of the Olympic Mountains across the Strait of Juan de Fuca, and headed back to the car. As mentioned in the previous post, much of the Olympic Mountain periphery rocks were composed of the same basaltic rocks.

In the dying light of the evening, I was going to try to make one more stop, Witty's Lagoon, to see what are said to be the best exposures of pillow basalts in the region. And I missed the turn. As a geologist and a life-long map-o-phile, I'm embarrassed even now to say that. And by the time I realized it, it was dark.  But we enjoyed a wonderful evening, with a late dinner courtesy of Red Robin in Victoria.

By the way, while I'm making confessions, about coming into Canada: If you want to not look like a complete doofus, learn how to pronounce the names of the places you are going to visit. At immigration, the polite officer asked why I was visiting Vancouver Island and I told him I was scouting out "Sookie" and "Na-na-emo". Eye-roll. It's "Sooke" with one syllable, and "Na-nymo" when you try to say Nanaimo. No wonder American tourists have a bad reputation....

Northern Convergence: America's Most Dangerous Volcano, and the End of the Journey

Northern Convergence as a name for this blog series was all about the role of a convergent plate boundary in the production of the scenery of the Pacific Northwest. The compressional forces that developed as the Pacific/Farallon/Juan de Fuca plate was stuffed under the North American continent formed range after range of complexly folded and faulted mountains hundreds of miles inland.

Perhaps the most vivid effect of plate convergence is the formation of a magmatic arc, a chain of inland volcanoes and underlying magma chambers. The oceanic lithosphere carries rock and water deep into the underlying asthenosphere where the rocks are heated, and the water liberated. The water has the effect of lowering the melting point of the mantle rock and plumes of molten magma form, which start moving upwards through the continental crust. Sometimes basaltic or andesitic magmas reach the surface. In other instances, the hot magma melts some of the continental granite, forming dacite or rhyolite.

Mt. Adams from Sunrise Ridge

Volcanism is one of the intense and spectacular geologic processes one could ever hope to witness (or avoid, if you not geologically-minded, or sane). Volcanoes are capable of horrific destruction and disaster, but they also provide rich fertile soils and incredible scenery. We had now been on the road for nearly two weeks, and an important early site for our investigations was to be Mt. Garibaldi and the Black Tusk, two of the northernmost Cascade volcanoes. As I wrote previously, rain and clouds obscured our views that day, and all we ended up seeing were some old lava flows (and, it should be said, some wonderful waterfalls).

Not a volcanic eruption, but instead a wildfire. Couldn't help imagining, though.

As we drove west on our final day, volcanism loomed. We would be passing through Mt. Rainier National Park, and it is hard to think of any mountain in the world that dominates the surrounding landscape the way Rainier does (Kilaminjaro comes to mind, or Mauna Loa in Hawaii, but few others). In stark contrast to our earlier visit at Garibaldi, the skies were crystal clear and sunny.

Mt. Rainier from the west

Rainier rises to an elevation of 14,411 ft (4,392 m), just a bit short of being the highest peak in the lower 48 states, but certainly the highest in the Cascades (only Shasta comes anywhere close at 14,179 feet). Glacial erosion has ripped away hundreds of feet of rock from the summit area, so at one time it was almost surely the tallest mountain in the lower 48 (one more contender though could be the San Francisco Peaks in Arizona, another stratovolcano missing thousands of feet from the summit).

Rainier from the air

For all of its grandeur, Rainier is an incredibly dangerous mountain. It contains roughly half of all the glacial ice to be found in the lower 48 states, around a cubic mile. That much ice and a tendency to have eruptions every few hundred years is a frightening combination. Many people think (perhaps influenced by bad Hollywood movies that involve volcanoes) that lava flows are the greatest hazard from volcanoes. They are not; lava flows would hardly be expected to get off the mountain massif itself. Andesite is just too sticky to flow far before congealing.

Source: Mount Rainier - Living Safely With a Volcano in Your Backyard by Carolyn L. Driedger and William E. Scott, USGS -- from USGS fact sheet 2008-3062

The ice is another matter. A modest eruption of ash or lava could melt a vast amount of ice, mixing with the ash to form a fast-moving mudflow called a lahar. Over the history of the volcano lahars have had the greatest reach, extending as far as the Puget Sound. The cities of Tacoma, Puyallup, Sumner and others are built on lahar deposits from Rainier (see above). Tens of thousands of people along the drainages below Rainier will have a few tens of minutes to evacuate in the event of a major mudflow. For all its beauty, the mountain is a ticking time bomb. It's also probably one of the most carefully monitored mountains on the planet. I don't doubt that the slightest hint of activity will bring a flurry of evacuations.

Rainier from the air in 2007

We spent a few hours on Sunrise Ridge, but our time was limited. We had nearly completed our journey and some of our people needed to catch flights at SeaTac. We headed down the hill towards Puget Sound. We had seen many wonders on the roads that took us across the Olympic Peninsula, the ferry to Vancouver Island, a rainsoaked drive through the Sea to the Sky Highway, explorations of Banff and Yoho National Park, a sojourn among the ghosts of dinosaurs on the High Plains, and a drive home through the Rocky Mountains and the Columbia Plateau. I had gotten to know an extraordinary group of people, and a small corner of a most extraordinary country, Canada.

Northern Convergence: Leaving a Beautiful Country

How will we deal with the hordes of people from the U.S. trying to invade our borders?

Our trip, the Northern Convergence tour, was not over, but the time had come to cross the border back into the United States from Canada. The trip thus far had been an eye-opener. We had been exploring the "crowded" part of Canada in British Columbia and Alberta, but the land itself exuded wildness and isolation.

We were on the High Plains east of the Rocky Mountains, and had spent the morning at the Head Smashed In Buffalo Jump World Heritage Site, and as gruesome as the name was, it was a fascinating place. From there we headed south to the border crossing at Carway. We figured since it had a name that there would be a town and facilities. We got there, and there was...one building. It was a duty-free souvenir/liquor/tobacco shop, and thank goodness, it had a restroom. Still, there were some picnic tables so we stopped for lunch and had a look around. We also wondered if the authorities were going to let us back into the United States. You never know...in the innocent days before 9/11, we were interrogated about whether we had any "Beanie Babies" in our luggage. I laughed at the question, and the border agent got very serious: "Sir, DO YOU have any Beanie Babies?"

We were not exactly in the High Plains, as the land was broken up into swales and shallow valleys underlain by very soft Cretaceous shale deposits. The shales had been deformed and twisted by the same convergent forces that had lifted the nearby Rocky Mountains, but erosion had smoothed off the sharp edges. The land was semiarid and treeless. More verdant lands could be seen in the distance as we looked westward towards the Rocky Mountains and Waterton-Glacier International Peace Park. Glacier National Park was our next destination.

Chief Mountain was especially prominent on the western horizon. The peak is an outlier of the Rocky Mountains, an isolated upper plate of a thrust fault that had pushed the hard Paleozoic limestones over the softer Cretaceous rock. Erosion had then isolated Chief Mountain as a klippe (see the diagram below).

The mountain was a dramatic welcome back into the United States. We only had a few more days left on our journey, but there was still much to be seen. The story will continue in another post!

Source: http://en.wikipedia.org/wiki/Klippe

Northern Convergence: Vancouver Island, the Plan That Was...Part I

Our Northern Convergence tour continues. Our first full day in Canada was to be an exploration of geological sites on south Vancouver Island between Victoria and the ferry port at Nanaimo. There was lots of research, and Mrs. Geotripper and I headed out to the island a few days before our students met us in Seattle. We had a plan...

But of course, there are plans that are made and there is what actually happens. So this post and a few more are explorations of the places we thought we were going to share with the students. What we actually saw with the students will be the subject of some other posts...

Deep rugged gorges are not one of the hallmarks of continental glaciation. Thick sheets of ice tend to smooth off the landscape, and since the ice left only 12,000-13,000 years, there has been precious little time for extensive river erosion. Yet a few kilometers west (we're in Canada now, think metric!) there is a deep rugged gorge. It is traversed by the Sooke River, which flows through a broad open valley before plunging through the gorge about six or seven kilometers north of the village of Sooke. It then flows into the Strait of Juan de Fuca.

The river has carved a series of beautiful potholes that are hugely popular with the locals. The gorge is preserved as Sooke Potholes Regional Park. It was pleasant place to visit. We happened to arrive late in the day, so there weren't many people about. We got out and wandered some of the trails.

As it turns out, the rocks in the Sooke gorge are basalt, part of the very same oceanic crust that makes up the outer "Horseshoe" of the Olympic Peninsula, and which makes up some of the most rugged topography at Olympic National Park. Because of plate geometry, the rocks of the Olympic Peninsula were pushed higher than those of Vancouver Island, and the continental glaciers on the island scraped them down even more. But there was a point where the basaltic rocks ended. It was just a few miles upstream of the Sooke Potholes, and is called the Leech River Fault. On the other side of the fault were much softer schist and other metamorphic rocks. In essence, the Sooke River flowed over soft rocks in a broad valley, but was forced by the glaciers to take a southerly route through the tougher basalts.

The river carved downward quickly, using large boulders as tools. The boulders, sometimes called "grinders", were caught in swirling eddies, would abrade and grind the holes they were caught in. Eventually the potholes became pools large enough to swim in.

Our plan was to take the students to the potholes, and then follow the road north to where we could see the Leech River Fault valley, but once we arrived on our scouting expedition, we found the campground closed for the year (undergoing renovations) and the road upcanyon blocked. We woud have to change our plans. Still, it was a spectacular place to wander. If you pay a visit, bring swimwear!

Northern Convergence: Stories on Trees, the Totems of the Northwestern First Nations

During the flurry of planning for our Northern Convergence journey through Canada and the Pacific Northwest, I was barely keeping up with the geology, and any background information on the anthropology/archaeology of the region fell to my colleague from our anthropology department. There were certainly some intriguing sights related to the First Nations people of  Canada, and the one of these impressed itself on me early in the trip.

We were rushing from one part of Vancouver Island to another, and I was running down the beach cliffs below Beacon Hill Park in Victoria while Mrs. Geotripper went wandering off somewhere.  I was vaguely aware that there was a really tall telephone pole or satellite receiver tower at the edge of the forest, and eventually I noticed that Mrs. Geotripper was motioning me over.

It slowly dawned on me that I was looking at one of the largest totem poles in the world. It was impossibly tall, and I had to go up and touch it to make sure it was made of wood. It was. The plaque at the base notes that the pole honors the First Nation people who fought in the world wars.

The pole was carved from a gigantic Western Cedar tree in 1956 by a team led by Mungo Martin, a Kwakiutl tribal chief. According to the city history, the pole was expected to last no longer than 50 years at which time it would return to the Earth. Major restorations a decade ago added some years, but it may not be there beyond 2020 or so. It stands 40.5 meters (133 feet) high, making it the fifth tallest in the world (or the tallest "free-standing"). The tallest in the world is in the village of Alert Bay on Cormorant Island at the north end of Vancouver Island. It is 53 meters (173 feet) high. We may not see many more poles of this height. There are few monster sized Cedar trees left to carve them from.

Totem poles haven't left much of an archaeological record for fairly obvious reasons. Wood disappears fast in this humid environment. They are known from the 1800s, and are known to have been present with some First Nation tribes prior to European contact. They are a beautiful art form, and communicate family histories, legendary stories, and clan status. They were apparently never objects of worship.

On our rainy day with the students on Vancouver Island, we made a stop at the town of Duncan in the Cowichan Valley, a region with a large First Nation presence. The town has embraced the display of totems, with around 80 in the town center. Each was carved by a local First Nation artisan..

It was an interesting area to take a break and learn a bit of local history. The town is also home to the Quw'utsun Cultural and Conference Centre run by the Cowichan tribe, the largest in British Columbia.

The rain continued (the blue skies in these pictures were from our reconnaissance trip a week earlier), and we needed to be in Nanaimo in a few hours to catch the ferry back to mainland. We drove north to Departure Bay. Our story will continue with our journey up the Sea to the Sky Highway.

Northern Convergence: Tragedy at Crowsnest Pass

Frank was a coal mining town of around 600 people in 1903. The coal seam ran along the base of Turtle Mountain, so the town was established there as well. The Canadian Pacific Railway also crossed the area on its way to Crowsnest Pass.

The local First Nation people did not like Turtle Mountain. They called it the "Mountain that Moves", and refused to camp in the area. The Europeans had no such worries, and mining of the coal was well underway. In the early morning of April 29, 1903, a shift of 17 miners was working deep underground. For weeks there had been strange things happening in the mine. Timbers holding up the tunnel walls would splinter and break for no apparent reason. Coal would occasional "mine itself", crumbling out of the seams overnight when no one was around. Small earthquakes were occasionally felt underground. The miners knew that the collapse of mine tunnels was an ever-present danger, so they may not have been overly surprised to hear the explosive concussion followed by an ominous silence. They were trapped, no doubt by a cave-in. They began to assess their situation. Soon, water was pouring into the tunnels, making a bad situation even worse.

The normal passage to the surface was blocked, but one of the miners knew that a second coal seam might be close enough to the surface that they could hack their way out. They started digging for all they were worth, gasping in the increasingly toxic air. One by one, the miners gave out. They weren't dead, but they just did not have the energy to pick up their tools. Only three of them were still working when they broke through to the surface. Rocks were still falling from above, so they couldn't yet escape, but they had fresh air, and they quickly cut another opening beneath a protective overhang. After thirteen horrible hours they emerged at the surface to find their experience was only a part of an even larger tragedy. A gigantic avalanche had buried part of their town, killing between 70 and 90 people. The miners had been given up for dead, so their appearance was some small bit of good news in the midst of the horrific event.

It gets to a certain point when driving through the mountain wilds of British Columbia and Alberta that one expects that trees will be growing just about everywhere. The region has plenty of precipitation through the year so things will be green. Approaching Crowsnest Pass during our recent Northern Convergence tour, we were struck by the sudden appearance of an absolutely barren slope. It doesn't take long to realize why, as the highway crossed a huge debris field covered with gigantic boulders. It was the debris avalanche that destroyed so much of Frank back in 1903.

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

The slide was truly epic in scale. Totaling 30 million cubic meters (82 million tons), the avalanche was 1,000 meters (3,300 ft) wide, 425 meters (1,394 ft) high and 150 meters (490 ft) deep. It spread laterally over level ground, covering three square kilometers. The rocks had flowed over the surface like a thick liquid at speeds of up to 70 mph (112 km/hr). The entire event was over in less than 2 minutes.

 The slide was probably inevitable. The limestone layers had been folded into a huge anticline (upward pointing fold) with thrust faults at the base, on top of weak Cretaceous sediments. Glaciation had oversteepened the flanks of the mountain. Fissures sliced deep into the rocks allowing water and ice to accumulate, weakening and wedging the rocks apart. The mining at the base of the slope was quite possibly a contributing factor.

Source http://www.uleth.ca/vft/crowsnest/slidedebate.html

The Frank Slide was the worst mass-wasting disaster in Canadian history. But life went on. The mines were reopened (a horse who worked in the mine was actually found alive after a month underground). The town grew even larger for a few years, but by 1917 the coal mines closed down. Today about 200 people live in the village nearby, and an interpretive center has been constructed that provides information on the extraordinary event.

We headed into nearby Pincher Creek for the night. It was our last night in Canada, but we still had plenty yet to see, on both sides of the border..

Source: http://occ.crescentschool.org/geography/physical/folding/frankslide.html

Northern Convergence: Vancouver Island, the Plan That Was, Part III

Road construction at Malahat Summit. Photo by Mrs. Geotripper.

Continuing my brief series of things my students didn't see on Vancouver Island during our Northern Convergence tour of Canada, we reach a place my students did in fact "see", as in we were there and looking around, but the students didn't see what we saw. Malahat Summit is 352 meters above sea level, about 1,155 feet, and is the local high point on this part of the Trans-Canada Highway between Victoria and Nanaimo. Several of my guidebooks called this a "must-see" stop, so I was anxiously watching for the turnoff. We then found out why scouting trips are a good idea...road construction had closed the summit rest area (above). I was disappointed, but found out I hadn't read the guides carefully enough, as the all-important viewpoint was actually a short distance down the hill.

Looking southeast from Malahat Summit towards Victoria and Saanich Peninsula. Without wildfire smoke, Mt. Baker would have been visible in the distance.

We pulled out and immediately noticed two things: the view was stunningly spectacular (I've been using those two words a lot), and there was room to park maybe half a dozen vehicles. When the students were with us in a few days, we would need a stroke of luck to have enough parking for our whole group (there would be no turning back on the narrow highway, and the viewpoint was busy).

Looking northeast from Malahat Summit.

Sometimes we don't always appreciate the scale of things. A thousand feet, 300+ meters, might not seem like all that much, but when you have been driving up a hill from sea level in a thick forest with no view, and a view suddenly opens up, it is like flying. The overlook is apparently at the top of an old marble quarry, so there is extremely steep terrain below.

The view extends across the Saanich Inlet to the Saanich Peninsula and beyond to the Strait of Georgia and the U.S. mainland north of Seattle. Though conditions were very clear, wildfire smoke obscured the distant horizon. Otherwise the volcanic edifice of Mt. Baker would have been visible (it turned out we had a bit of trouble seeing volcanoes on this trip). The Peninsula is a lowland covered mostly by glacial debris with occasional knobs of bedrock sticking out. The moderate climate makes the peninsula a good region for dairy farms and botanical gardens. Butchart Gardens were directly across the Inlet from our location, filling an old marble quarry (the marble is Triassic in age, metamorphosed from shallow marine limestone).

Do you have a sense of the scale of things yet? The barren brown field on the peninsula in the picture above is actually Victoria International Airport. And that little boat in the pictures above? It's actually a good-sized ferry.

BC Ferry in Saanich Inlet. Photo by Mrs. Geotripper.

In the near rainforest environment along the highway, rocks are sort of a rare sight. We saw lots of them, though, courtesy of some major road construction activity, but there was nowhere to stop and take a closer look.

Road construction at Malahat Summit. Photo by Mrs. Geotripper.

There were also rocks behind us at the viewpoint, which I briefly glanced at, seeing some kind of nondescript metamorphic rock of some kind. I found out later from the guidebook that this outcrop was actually granitic rock. It's simply been covered by a cement-like coating of limestone dust from the quarry activities down below. I've been fooled by this sort of thing before, most notably at Tehachapi Pass in Southern California.

Granite covered by lime dust near Malahat Summit. Photo by Mrs. Geotripper.

So...this business of what we saw and the students didn't? We actually made it here a few days later. We had time, and we even had parking! We pulled off the highway and saw...nothing. We had driven right up into the cloud cover and were surrounded by an impenetrable fog. I said nothing about what they were missing, and most of them probably don't even remember pulling out for a moment at the locality. As I've said before, the students had an interesting day and saw great things, but not this at this spot. Some days are like that.

I've mentioned guides that I was using. Two of the most useful were The Geology of Southern Vancouver Island by Chris Yorath, and Geology of British Columbia by Cannings, Nelson, and Cannings.