journey by ferry that we used to get there, we've looked at one of the toughest hikes I've ever taken for a bird's eye view of the sound, and a look at some of the engineering required to live in a vertical place.
The mine was certainly productive, however. During the 70 years the mines operated, ore totals included 650,000 tons of copper, 137,000 tons of zinc, 17,000 tons of lead, 500 tons of cadmium, 188 tons of silver, and 15.6 tons of gold. The gold alone would be worth $750 million at current prices. My rough calculation of the price of the copper the mine produced is $3.4 billion.
They also demonstrated the carbide lamps that were used for lighting in the mines for many decades (above). Better than candles, certainly, but I would want some bright flashlights, and a bunch of them. Being lost in a totally dark mine (or cavern) is one of my serious phobias.
They allowed us to wander a little bit around the ground floor of the mill, and I was able to pick out something sort of unique. In the wet environment, copper carbonate stalactites have formed on some of the girders!
All in all, a great experience. If you are ever in Howe Sound, consider the tour at the Britannia Mine. Information can be found at https://www.britanniaminemuseum.ca/.
Thursday, October 24, 2019
Tuesday, October 15, 2019
Its Really Been That Long? 30th Anniversary of the Loma Prieta Earthquake on Thursday
It's Earth Science Week, and "Geoscience is for Everyone" is the theme for this year. Geoscience IS for everyone, because geology dominates the lives of everyone. No one can escape it, for better or worse. Better, when we find inspiration in the awesome forces that have made our planet, and worse for the geologic hazards that exist everywhere on the planet in one form or another. Here in California, one of the premier hazards are the earthquakes that occur here with disturbing irregularity (it would be so much nicer if they followed schedules so we could prepare). I'm writing about the anniversary of the Loma Prieta earthquake a few days early, but we had two moderate earthquakes in less than 24 hours in Northern California (magnitude 4.5 and 4.7), so seismic things are on my mind.
We can only share our stories to keep that knowledge at the forefront that will allow us to survive and recover from the major earthquakes to come. Here's my story from 1989, when my teaching career was just beginning.
On October 17th, 1989 at 5:04 PM, my physical geology laboratory had just finished and almost everyone had gone home to watch the World Series. A couple of students were helping me (it was Maureen and Sonny; funny how I remember the names of the first students I had better than the ones I had last semester). We were 100 kilometers from the epicenter, so when the seismic waves started to shake our building, the movement was a strong rolling motion instead of sharp vibrations. We looked at swaying TV monitors, and commented that it was an earthquake. It was a most scholarly discussion, actually. We realized the shaking was not stopping, and we thought we could sense the direction of the quake as well. We started to guess where it might be happening, but when the shaking reached the 40 second mark (the energy was spreading out, it lasted only 10 seconds or so near the epicenter), we realized it was a major event, and that fatalities were probably occurring (and unfortunately we were right). The deodar trees out the window were whipping back and forth as if they were in a high wind. The strangest part for me was the unconscious decision I was making as the shaking progressed. Despite having a quiet scholarly discussion, my body was moving from the front of the podium to the back, where there was a nice solid space to hide under. I would have dived under if the quake had lasted any longer.
In hindsight, I should have been a bit more aggressive about taking shelter under the desk. An analysis of our building a year or two later revealed an architectural weakness that suggested the building could collapse if the seismic waves hit it from a particular direction. A seismic retrofit a decade later included some massive shear walls in the lab I taught in.
|Two good-sized earthquakes as recorded at Modesto Junior College|
|No, this isn't what happens (credit: A. June)|
|Well, this can happen, but most people survive, even in the worst of quakes (credit: A. June)|
Meanwhile, at the city library, my children were making me proud. At the time of the quake, there were huge sailing ship models on display, in some cases right on top of the book stacks. The stacks were not reinforced or braced, so there was a real potential for injuries if the quake was strong enough to knock those stacks over. I was told that most people were just standing there watching the bookstacks swaying, but my kids, my well-trained and intelligent kids were the only people in the room to take shelter under the sturdy study tables. Luckily, as I said before, we were on the fringes of the effects of the earthquake and no one was hurt.
The Loma Prieta earthquake, a magnitude 6.9 event at a depth of 11 miles, was a tragedy: 63 people died, and 3,700 were injured. If the World Series game between the A's and the Giants hadn't been about to start, the death toll would have been much higher. Traffic was stunningly light that afternoon. Despite this, the Bay Area was in chaos for days, and months passed before life got back to normal. We were on the fringes, so instead of pain and suffering, we had a profound learning experience that was remembered by my students for the next decade and a half. But it has been 30 years now, and many of my students weren't born when the quake happened. Few of them have felt a quake at all. The large quakes like Loma Prieta and Northridge are ancient history, and there is less of that innate knowledge of what they should do when one hits. Few admit to having any kind of emergency kits at home, and they have no plan for what to do when the next big one hits.
Fault studies across California make it clear that more big tremors are coming, almost surely within the next decade or two. We educators must keep these past events alive in the minds of our students so they will be ready for these events when they come.
This is an abridged version of a blogpost from 2009.
This is an abridged version of a blogpost from 2009.
Posted by Garry Hayes at 9:09 PM 1 comment:
Monday, October 14, 2019
Travels in Cascadia: The Toughest Hike I'll Ever Do...Stawamus Chief in British Columbia
Stawamus Chief is a granite dome that rises more than 2,000 feet above the east end of Howe Sound, the southernmost fjord on the west coast of North America. The dome actually has three summits, the 1st, 2nd, and 3rd, and the trail climbs to the first summit in a little over a mile. That doesn't sound so bad, does it?
Stawamus Chief was different: as I approached the summit, a most unusual rock emerged from the trees. It was a boulder perched on a granite platform. It was a classic example of a glacial erratic, a rock left behind as the glaciers that flowed over this surface melted away. Unlike Half Dome, the summit of the Chief had been covered by glacial ice. And not just a little...the ice here was over a mile thick!
Posted by Garry Hayes at 1:05 AM No comments:
Labels: British Columbia, exfoliation dome, glacial erratic, granite, Howe Sound, Squamish, Stawamus Chief, Travels in Cascadia
Saturday, October 5, 2019
Travels in Cascadia: Howe Sound and the Challenge of Living in Vertical Places, Part 1
|We didn't fly over it, so I've clearly needed to borrow this image from Google Earth.|
We have (slowly) been reviewing our geological exploration of British Columbia back in July, and when I last posted we had reached Howe Sound, the southernmost fjord on the west coast of North America. We arrived by ferry at Horseshoe Bay (from Vancouver Island), and then spent two days exploring the museums and parks of the city of Vancouver. But now we were headed into the interior, and needed to follow Highway 99 along the south side of Howe Sound.
Howe Sound is, as noted earlier, the southernmost fjord in western North America. A fjord is a glacially carved bay, and as such has nearly vertical rock walls sloping down to the waters of the bay. This kind of topography entails serious engineering difficulties for anyone who wants to live in, travel through, or mine in the fjord. Prior to the 1960s, the only form of transportation to the inlet of the bay at Squamish was by water. A railroad was completed between Squamish and Vancouver in 1956 (after a delay of something like 40 years), and the first iteration of Highway 99 was carved out of the walls of the sound between 1958 and 1969. When Vancouver was selected as the site of the 2010 Winter Olympics, the highway was widened to four lanes to provide access to Olympic venues in the Whistler area.
The development of transportation corridors led to the development of a few small towns and villages along the route. And that caused problems in this steep countryside. We stopped in the little village of Lions Bay to have a look at a perilous situation.
For more details about the geology of the Sea to Sky Highway and the engineering challenges, check out: http://quimpergeology.org/wp-content/uploads/2018/03/Sea2Skytour.pdf
Posted by Garry Hayes at 6:48 PM No comments:
Labels: British Columbia, debris flow, glacial fjord, Howe Sound, Lions Bay
Subscribe to: Posts (Atom)