Explore the Pacific Northwest and Northern Rocky Mountains with Geotripper! June 17-July 1, 2017

Grand Tetons National Park, Wyoming

Be forewarned. This post is a TRAP! It is designed to draw you in, weaken your defenses, and cause you to do something different than everyday life. Warning given...

Have you ever dreamed of hitting the open road and finally seeing those places you've dreamed about, but haven't acted on that dream yet? What if you found out about an excursion that doesn't just tour, but allows you to learn the geology and history of those wild places? A tour on which you can even earn college credit? AND, a tour that is affordable? Maybe this is the one...

Mt. Shasta, a Cascade volcano in northern California

From June 17-July 1, 2017, the geology department of Modesto Junior College will be conducting a field studies course (Geology 192) in the Pacific Northwest and Northern Rocky Mountains. It will be a three semester unit course designed for our community college clientele: first year geology majors, potential geology majors, and community members (especially teachers) interested in geology and natural history. We will develop the necessary geological background prior to and in the early days of the trip, so people of all backgrounds are encouraged to attend. The total cost is $800 which will include all food, camp fees, entrance fees, transportation costs for the trip. The tuition cost for the three units of semester credit will be around $180 (out of state tuition is higher, around $200 a unit, which is still a deal). The only additional costs should be for showers, laundry, books and other souvenirs, and junk food (we provide healthy food for the most part; if you want Twinkies you are on your own!). We will be camping each night, and the school provides the transportation (vans). The excellent meals are planned by our professional volunteer staff, and cooked by the participants under their watchful eyes.

Lava Tube in Lava Beds National Monument

What will you see and experience? On the 17th we'll leave MJC and drive north through the Great Valley of California and arrive at the south end of the Cascades Range. The huge edifice of Mt. Shasta looms over the north state at 14,163 feet, and still is potentially active. It last erupted in 1786. Depending on snow conditions, we'll climb to the 8,000 feet level at the old ski bowl and have a close look at the rock and ash deposits. We'll continue north and end the day at Lava Beds National Monument near the Oregon border. There will be chance to explore some lava tubes while we are there.

The view from Smith Rock State Park in Oregon

We drive through Oregon the next day, with possible stops at Crater Lake National Park and Newberry Crater (depending, once again, on snow conditions). Camp will be at Tumalo State Park. The following day we will explore Smith Rock State Park (above), Mt. Hood, and the Columbia River Gorge (if there is time we will climb Beacon Rock in the gorge). The third camp will be at Seaquest State Park at the foot of Mt. St. Helens in southern Washington.

Mt. St. Helens in Washington. It erupted in 1980 and 2004

The following day will be devoted to the exploration of Mt. St. Helens (weather allowing!). We'll then descend the eastern flank of the Cascades (including a close look at Mt. Rainier) and drive onto the Columbia River Plateau, a vast basalt plain that covers much of eastern Washington and Oregon. Camp will be at Wanapum State Park on the Columbia River near Vantage.

Dry Falls State Park in Washington. The floodwaters covered this entire landscape to a depth of 300 feet during the Spokane floods.

The next day we will view the evidence for vast floods that swept across the plateau during the Pleistocene ice ages. The discovery of these floods by J Harlan Bretz in the 1920s and the long road to acceptance of the hypothesis by the geological community is one of the great stories in the history of geology as a science. We'll have a look at the Channeled Scablands, Soap Lake, and Dry Falls as we travel east through Washington. We'll spend the night at Riverside State Park in Spokane, Washington.

Lake McDonald in Glacier National Park

We'll head through the copper mining districts of Idaho and into Montana where we'll see more evidence of the ice age floods, including the Camas Prairie where ripplemarks 30 feet high can be found. We'll end the day in a special place, Glacier National Park on the Montana-Canada border. We'll spend two days exploring the park, with chances at several hikes. The park is a showcase of glacial erosion, but the glaciers that exist in the park today are expected to be gone within a decade or two because of global warming.

Saint Mary Lake in Glacier National Park, Montana

When we leave Glacier, we'll head south through the high plains on the east side of the Rocky Mountains and end the day at the KOA in Bozeman, Montana. We'll check out the Museum of the Rockies, and depending on snow conditions, explore some of the high mountains that surround Yellowstone, and eventually drive the Beartooth Highway into Yellowstone, America's oldest national park. We'll spend two days exploring this incredible park.

Yellowstone Falls in the Grand Canyon of the Yellowstone River

There is the Grand Canyon of Yellowstone, and a menagerie of incredible animals, including elk, bison, moose, bighorn sheep, and if we get really lucky, wolves.

Wolf near Norris Geyser Basin, Yellowstone National Park

Then there are geothermal features for which Yellowstone is so famous. Grand Prismatic Spring, for instance, and 70% of the world's geysers (there's lots more besides just Old Faithful!).

Grand Prismatic Spring, Yellowstone National Park

We'll then head south and spend two days at Grand Tetons National Park with time for some spectacular hikes. Then we start the road home with a drive through northern Nevada to Berlin/Ichthyosaur State Park to see the fossilized remains of the behemoth swimming reptiles from the age of the dinosaurs. Finally, we expect to see Mono Lake and the high country of Yosemite National Park. If snow blocks our path, we head home over Sonora or Carson passes.

Big Geyser (not Old Faithful!) in Lower Basin, Yellowstone National Park

It's hard to describe the wonders that exist across the Pacific Northwest and Northern Rocky Mountains without getting an overwhelming urge to get up and leave right away. If you are interested in joining us this summer, please check out the course web page at http://hayesg.faculty.mjc.edu/GeologyPacificNorthwest.html and join our Facebook page at https://www.facebook.com/groups/185168445318910/. If you are in the Modesto region, we are having an information meeting on Monday, April 10 in the Science Community Center on the west campus of the Modesto Junior College at 7 PM in SCC 326 (attendance is not mandatory to go on the trip). We hope you will join us!

Here We Go Again: Yellowstone is Going to KILL US ALL! Wait a minute...

I'm going to start with the conclusion (I've highlighted some parts using the bold font):

Geological activity at Yellowstone provides no signs that a supereruption will occur in the near future. Indeed, current seismicity, crustal deformation and thermal activity are consistent with the range and magnitude of signals observed historically over the past century [Lowenstern et al., 2006]. Over the past two million years, trends in the volume of eruptions and the magnitude of crustal melting may signal a decline of major volcanism from the Yellowstone region [Christiansen et al., 2007; Watts et al., 2012]. These factors, plus the 3-in-2.1-million annual frequency of past events, suggest a confidence of at least 99.9% that 21st-century society will not experience a Yellowstone supereruption. But over the span of geologic time, supereruptions have recurred somewhere on Earth every 100,000 years on average [Mason et al., 2004; Sparks et al., 2005]. As such, it is important to characterize the potential effects of such events. We hope this work stimulates further examination of ash transport during very large eruptions.

The reason I am doing so is because the media is reporting on the body of the report that came out recently concerning the possible effects of a major caldera eruption at Yellowstone National Park. That means we are getting the usual headlines like:

If Yellowstone Supervolcano Erupts, Ash May Reach NYC

Yellowstone Supervolcano Eruption Would Doom the United States

Eruption of the Yellowstone Supervolcano will turn the US into a Third World Country

Eruption of Yellowstone supervolcano could spell the end of the US

For the most part, the reports themselves aren't too bad (there ARE exceptions). The thing is, we've always known that a Yellowstone caldera plinian supereruption would be devastating. That's old news. The purpose of the research was to model the potential effects of such an event. I get that disaster and omens of disaster are what sell newspapers or put eyes on advertising, so headlines go over the top, just like they always have. But this approach leaves the readers with the wrong impression, and they are going to worry about whether eruptions of Yellowstone need to be added to their fears of terrorist attacks, Megalodon shark attacks on their Caribbean cruise, or whether vaccines cause autism. In other word, useless levels of stress based on incorrect or blatantly wrong information.
 
I want to send kudos to a couple of media outlets with less sensationalistic headlines, such as those from the Billings Gazette: Researchers predict ash fall if Yellowstone supervolcano erupted or the Daily Digest: New computer models show likely fallout of a volcanic eruption in Yellowstone.
These kinds of headlines actually communicate accurate information without the terror-inducing yellow journalism.

This report from the U.S. Geological Survey serves a useful purpose. It is part of the kinds of research that can help cities, states, and nations plan for and cope with natural disasters when they occur. The authors were careful to state in their conclusions the extreme unlikelihood of a rhyolite caldera eruption, but their computer model might be useful in predicting the effects of lesser eruptions elsewhere in the world, eruptions that are far more likely.

You can see the report here:
Mastin, L. G., A. R. Van Eaton, and J. B. Lowenstern (2014), Modeling ash fall distribution from a Yellowstone supereruption, Geochem. Geophys. Geosyst., 15, doi:10.1002/2014GC005469. 

But don't fret. There are still the Yellowstone WOLVES to worry about!

"Supervolcano" Causes Road to Melt! Hmm, About That...

"Parts of Yellowstone National Park closed after Massive Supervolcano beneath it melts road!" screams the headline in a typical treatment of a modest story out of one of our nation's premier national parks. Let's take the fact that there was a modest sized earthquake a few months ago, and add a video of bison running away from (actually trotting towards) Yellowstone, and you have the makings of a huge non-story. The world is going to end because the "supervolcano" is going to explode and kill us all!

Is the story wrong? In a tortuous sort of way, the story is "accurate". Yes, a road was closed "between" Old Faithful and Madison Junction, insinuating that a major throughway is blocked. It's actually a small side road. The melting of the asphalt was "caused by the massive supervolcano". Technically this is true. All of the geothermal features at Yellowstone are caused by the magma chamber of the "supervolcano",  which heats the groundwater, turning it to steam, which rises through the crust to melt asphalt. But asphalt can melt on really hot days in the desert too.

I don't know...I would think that the people who live and work on top of the gigantic "supervolcano" (more accurately termed a rhyolite caldera) would be a little more worried about their well-being if the volcano were about to blow. Instead, here is the original news release from the park: "Firehole Lake Drive Temporarily Closed" . You can just feel the barely restrained panic in the air... 

Geyser erupts on top of massive supervolcano!! Note the extreme panic in the crowd!

Yellowstone is a fascinating place  with a violent geologic history. But the last eruption was 70,000 years ago. Someday, most likely long after we are all dead and gone, it will erupt again. For the time being, nothing much is happening except for boiling and steaming water. Go see it. And try to ignore the screaming headlines, and enjoy the fact that we have such a fascinating place to see and visit.

DEATH, FIRE, EXPLOSIONS, END OF CIVILIZATION! YELLOWSTONE! OMG! Um, about that...

"Bison and many other animals are leaving Yellowstone in droves, and its (sic)prompting theories that minor earthquakes in the area could soon set off the Yellowstone Super Volcano." Source: click here

How many things can be wrong in one sentence? I count at least three or four. To begin with, the viral video that has the rumor mill going crazy apparently is showing a herd of bison rushing into Yellowstone National Park, not out. And I wouldn't be surprised that animals are leaving for lower elevations in any case. There is a decided lack of food higher up. They do it every winter.

Then, the word "theories" gets casually tossed into the mix. Speculation on the basis of very limited (or absolutely no) evidence is not a theory (a model or idea confirmed by extensive testing). The speculation in the sentence above doesn't even rise to the level of an hypothesis, which nearly all school children call an "educated guess". "Hypothesis" is reserved for ideas and models that are plausible.

The minor earthquake was a magnitude 4.7 event. The largest in thirty years. So what? It's still a minor earthquake. There are hundreds or thousands of earthquakes in Yellowstone every year, and the caldera hasn't exploded. There was a quake with a magnitude of 7.3-7.5 back in 1959. That quake, which killed 28 people was thousands of times more powerful than the quake last week. Why didn't the caldera explode back then?

It comes down to ignorance of basic geologic principles on the part of journalists and the fear-mongers on the web. Having a little bit of knowledge is sometimes as damaging as having no knowledge. People have been told by cable channel documentaries over and over that Yellowstone is a "supervolcano", which was never a geologist's term. They pick up that there was a truly colossal eruption 2.1 million years ago, another 1.3 million years ago and another 640,000 years ago. OMG it's a pattern and we're all going to die! Next week!

The gentle fact is that Yellowstone has not had a volcanic eruption in 70,000 years. There is indeed a large body of molten magma beneath the park, but it has been there for millions of years, and there are currently no signs of unusual activity. From studies of calderas around the world, it is clear that many warning signs taking place over centuries would give humans plenty of time to figure out how to deal with the eventuality of a major eruption.

There are many things to worry about in the world these days, but a gigantic eruption at Yellowstone is not one that I lose sleep over. When you read someone's frantic post about "the BIG ONE" shaking up Southern California or supervolcanoes destroying civilization, make use of one of the most powerful human tools ever invented. Take to the internet, the greatest repository of human knowledge ever constructed, and investigate.  Don't seek out the idiots who post rumors and innuendo. Find out what the real geologists are saying before hitting that "share" button. Don't get Snoped by your more intelligent friends. It's really embarrassing.

And that goes double for "journalists". What you have done with is non-story is irresponsible. At the very least, read an analysis by a responsible blogging expert like Erik Klemetti at Wired before writing anything on your own.

A Convergence of Wonders, Day 11: The Orange Steam is OK, but the Blue Stuff Will Kill You....

Say what? Oh yeah, I was once working on a series about our journey across the Pacific Northwest and the Northern Rocky Mountains in June called a Convergence of Wonders (the name derived from the influence of the Cascadia Subduction Zone, a convergent boundary). I had reached day 10 when we arrived and started exploring Yellowstone National Park, but was, uh, slightly distracted by another two week trip, a more personal trip. I'm home now, and I expect to wrap up this series now.

So what is today's title about? Well, the steam at Yellowstone National Park actually does have some bad stuff in it (high levels of carbon dioxide and hydrogen sulfide) and can cause some real problems for people with asthma and other conditions, but there is no blue steam or orange steam, except as it reflects the colors beneath it. The picture at the beginning is of Grand Prismatic Spring in the Midway Geyser Basin.

Yellowstone is justly famous for her collection of geothermal features; the 300 geysers in the park account for about two-thirds of all the geysers in the entire world. There are thousands of other fascinating geothermal features as well, including fumaroles, boiling mudpots and hot springs.

Fumaroles are steam vents. Sometimes fumaroles are short-lived features in the immediate aftermath of violent volcanic eruptions, but in places like Yellowstone (and Lassen Volcanic National Park in California) they are more permanent in nature. Sometimes they are transitional in nature, depending on the time of year and availability of groundwater. Some geysers erupt so rarely that they might as well be considered fumaroles that occasionally explode.

Boiling mudpots are cauldrons of hot acidic mud derived from the weathering of the surrounding volcanic rock. The bubbling mud above is the Fountain Paint Pot near the Lower Geyser Basin.

Hot springs are carefully defined as springs that have, uh, hot water. They are one of the most beautiful of Yellowstone's geothermal features due to the interplay of color caused by select absorption of sunlight and the presence of extremophile bacteria (which can survive in near-boiling water). Grand Prismatic Springs is one of the most spectacular features in the national park system, although it is hard to see except from above (there is a trail on the nearby hillside).

The hot spring we looked at in the last post, Mammoth Hot Spring, was a mountain of calcium carbonate derived from the solution of limestone layers along the pathway of groundwater movement. Most of the hot springs in the park are within a rhyolite caldera, and most of the springs have much less voluminous deposits made mostly of silica. White Dome Geyser, below, is the highest silica dome in the park at twelve feet.

No trip to Yellowstone would be complete without a visit to Old Faithful. At least that's what I've heard. I managed (quite on purpose) to miss two eruptions while we were there. There's just something about having amphitheatre seating and a giant crowd of people that is off-putting.

So what were these people standing around for? The rangers seemed far more excited about convincing people to see an eruption of Beehive. Is that it, that little bit of spray?

Oh, there it is! It produced a spectacular eruption!

As we started south to leave the park, we made a short stop at Grant Village to have a look at Yellowstone Lake, a huge body of water (132 square miles) that is the largest freshwater lake above 7,000 feet in the country, and possibly the world. The lake lies within the Yellowstone Caldera, and recent activity has caused parts of the lake bottom to tilt. Some shorelines are rising and others are falling.

I also took a moment to say hi to Nina Fitzgerald, a ranger at Yellowstone. She is a fellow geoblogger, and has been writing a great series of posts about her experiences in the park system. You can catch her work at Watch For Rocks.

We ended our day by traveling south along the Rockefeller Byway to Grand Teton National Park. More in the next post!

A Convergence of Wonders, Day 10: Exploring a Real Hot Spot

It was day 10 of our field studies journey through the Pacific Northwest and Northern Rocky Mountains. We had finally arrived at one of the flagship destinations for our trip: Yellowstone National Park! One of the crown jewels of our national park system, home of Old Faithful...we set aside two days to explore the park, and I did something slightly devious to my students. I spent the entire day looking at "not geysers"!

Frankly, I'm not sure any of the students noticed the distinction. That's the thing about Yellowstone; it is so full of wonders and curiosities that it would be a unique landscape to explore even if there were no geysers to be seen at all. We spent our day exploring the northern loop of the park, from Canyon Village and the Grand Canyon of the Yellowstone to Mt. Washburn and then to Mammoth Hot Springs. We stopped in at Norris Geyser Basin at the end of the day, but were distracted by a wolf.

It's funny about furry charismatic animals; they seem to trump the attention of everyone, especially geology students. Our first stop of the day had nothing to do with geology at all, it was to photograph an elk. One cannot travel fast in Yellowstone National Park, because there are constant traffic jams caused by tourons (tourist morons, including ourselves...) looking at bison, elk, bear, moose, beaver, or wolf. I was immune to the effect. I took only ten pictures of this particular elk...

We explored several overlooks at the Grand Canyon of the Yellowstone and Lower Yellowstone Falls. The colorful walls of the canyon are composed of weathered rhyolite just over 500,000 years old. This canyon has been cut very rapidly! 

Standing at the brink of the 308-foot-high Lower Fall of the Yellowstone, one can feel the powerful surge of the water as it disappears over edge. It's not hard to believe that such a deep canyon could be carved by a river like this.

The most astounding story to be learned at Yellowstone was never envisioned by those who established Yellowstone as our first national park in 1873 (Yosemite was set aside nine years earlier, but as a state park). We drove to the high ridge near Dunraven Pass and Mt. Washburn to have a look around.

There is a fable about several blind men who were touching an elephant and disagreeing about its nature, whether it was like a rope (the tail), a snake (the trunk), or a tree (the leg). Yellowstone's most striking feature was so big that it was decades before geologists recognized it for what it was: a vast caldera, the site of three of the largest volcanic eruptions to ever hit the North American Continent in recent geologic time (2.1 million, 1.3 million, and 640,000 years before present).

How big is the caldera? The snowcapped mountain in the distance in the picture below is Mt. Sheridan. We were standing on the side of  Mt. Washburn; there is a forty mile gap between the two. The mountain ridge that connected the two peaks sank into the caldera during a single massive eruption that put 600 cubic miles of ash into the atmosphere. The ash spread for thousands of miles. A repeat eruption would be devastating to civilization (despite what the television tells you, such eruptions are not imminent, nor are they overdue; we would see signs of caldera unrest dozens, if not hundreds of years beforehand). The source of these eruptions is thought to be a mantle hot spot, although there are several alternate interpretations.

Volcanism has been influencing events in the Yellowstone region for a long time. In early Cenozoic time, around 50 million years ago, the region was rocked by numerous eruptions that produced volcanic mudflows (lahars) that overwhelmed forests of sequoia/redwood trees (You thought they were found only in California didn't you? They were once much more widespread). Each time a forest was destroyed and buried, a new forest would grow in the sediments. That forest was destroyed in turn, and over time dozens of layers containing petrified logs accumulated. These forests are generally hard to access by road or trail, but one solitary upright trunk can be seen in the north part of the park. There used to be three here, but souvenir collectors carted off the others, which explains the prison in which the trunk resides.

We moved on down to Mammoth Hot Springs (with a few bear diversions), and took a look at the strange edifice of calcium carbonate. Most of the hot springs and geysers of Yellowstone do not produce massive mineral deposits, but they happened here, outside the boundaries of the caldera. Most of the water emerging from geothermal features in the park is charged with silica, but at Mammoth, the water has passed along faults that traversed Paleozoic limestones. The acidic waters dissolved the calcite making up the limestone, and when the waters emerged here, the calcite came out of solution.

The hot springs are constantly growing and changing location, so the deposits never look quite the same. Heat-tolerant bacteria provide a splash of color to the otherwise snow-white rock.

Spelunkers (cavers) will recognize many of the deposits, as they are similar to flowstone features found in many limestone caverns, especially the rimstone pools seen in the pictures below. Exploring Mammoth Hot Springs is kind of like exploring an inside-out cavern...

 The rimstone pools were especially photogenic...

There were several killdeers strolling across the pools...

We drove on in the late afternoon to Norris Geyser Basin, but I didn't get any pictures. We were distracted by the whole charismatic mammal thing anyway, the subject this time being a Canis lupus enjoying a meal in a meadow north of Norris.

You can see the whole wolf drama in this post.

We were done with another day...tomorrow would include the famous geysers (maybe), and Grand Teton National Park.

I've been posting regularly for the last ten days, but I am hitting the road again tomorrow, so the next few posts will be at unpredictable intervals, as web access will be tricky. Take care, all!

A Convergence of Wonders, Day 9: Into the Depths of the Crust, and of Time

We've been traveling through the Pacific Northwest and northern Rocky Mountains on a class in geology and archaeology for the last nine posts. Yesterday we made our way south from Glacier National Park over a corner of the Great Plains. Today (that is, June 23rd) we would be headed someplace different: down to the deepest part of the Earth's crust, and into the depths of geologic time. We were going to have a look at some of the oldest rocks on the planet.

How does one get to the base of the Earth's crust, or even into the mantle? Given that the base of the crust is 15 or 20 miles beneath us, and the deepest tunnel ever dug is 2 1/2 miles, one cannot walk or ride there. What we have to do instead is find a place where the crust has been brought up to us. Such a place is the Beartooth Mountains on the Montana/Wyoming border near Yellowstone.

In late Cretaceous and early Cenozoic time, around 70-50 million years ago, the crust in the Rocky Mountains was being twisted and deformed by an errant and misguided slice of Pacific Ocean crust that had somehow become trapped sliding along the base of the continental crust until it reached Montana and Wyoming, where it was finally able to sink. The mountain-building event, which formed much of the Rocky Mountains (including the mountains around Glacier National Park), is called the Laramide Orogeny. The rocks of the Beartooth Mountains were pushed up and over Cretaceous sedimentary rocks. Way, way up. The rocks originated in the deepest part of the continental crust, and these rocks are old. Very, very old.

Our first stop was within the Stillwater complex, a unique sequence of rocks that may have originated in the deepest parts of the crust, and which may have had an ultimate source in the Earth's mantle very close to the outer core. The Stillwater complex is a layered intrusion, a pluton composed of various kinds of peridotite and gabbro (the rocks are composed largely of the mineral olivine, which is also known as the gemstone peridot). It formed 2.7 billion years ago, making these rocks almost the oldest we would see  on the trip (more in a moment). Such complexes are quite rare at the Earth's surface, and contain an interesting mix of rare elements and minerals. We were parked near the Stillwater Mine, which is actively extracting platinum, chromium, and other rare metals. The mine dumps include some nice samples of magnetite, olivine, pyrrhotite and other interesting minerals.

By early afternoon, we were done with the Stillwater, and headed to Red Lodge for a class in the park. The students were listening with rapt attention, they said. Their closed eyes made it easier for them to concentrate on the meanings of the words they were hearing. That's what they said, and since students in my classroom are always saying the same thing, it must be true...

Red Lodge marks the beginning of one of the most remarkable roads in the United States, the Beartooth Highway. From an elevation of about 5,600 feet, the road climbs to the summit region of the Beartooth Plateau at just short of 11,000 feet. It is a marvelous place to see the work of glaciers, but even more stunning is the age of the rocks that the road is built on.

The rocks are composed of metamorphic rocks like gneiss, schist, and quartzite, with an occasional intrusion of granitic rock. The rocks formed between 2.7 and 3.3 billion years ago, which makes them very old (more than a billion years older than anything in California), but remarkably, fragments in the quartzite are even older! Zircon is a very tough mineral that resists being destroyed by erosion or metamorphic activity. Grains of zircon survive the Earth's recycling process that tends to destroy almost any other mineral. Quartz is another durable mineral, but it cannot usually be dated easily, but zircon can be dated. Grains of zircon in these mountains have been dated at 4 billion years. For comparison, the Earth itself is 4.6 billion years old. These grains in these rocks are the most ancient objects I've ever held that didn't fall to Earth from space (meteorites are generally leftovers of the origin of the Solar System and are the same age as the Earth).

The Beartooth Highway provided the most spectacular glacial features seen on our trip outside of Glacier National Park. The picture above shows a wonderful example of a U-shaped valley. Glaciers tear away at the walls of a valley, unlike a river, which only erodes the valley bottom. Glaciers cannot turn corners well, so the U-shaped valleys tended to be very straight. Hanging valleys, smaller glacial troughs that couldn't cut to the same level as the trunk glacier, are seen high on the main valley walls.

The Beartooth Mountains take their name from the "fang" seen in the picture below, beyond the head of the circular valley called a cirque. These bowl-shaped valleys in the highest reaches of the mountains were the origin point for the glaciers (snow would blow off the highest summits and ridges, so glaciers couldn't form on them, but in the shaded cirques instead). Sharp knife-edged ridges between glacial valleys are called aretes (not pictured).

It was strange to drive from summer to winter in the space of an hour. The road had opened to traffic only a week or so before we arrived.

The summit plateau provided a wonderful panorama of the Beartooth and Absarokapre-European period.

As we drove out of the Beartooths towards tiny (and somewhat unfriendly) Cooke City, we had a nice view of Pilot Peak, an outstanding example of a glacial horn, a spike of rock that has been plucked by glaciers from three sides or more.

Driving through the Lamar Valley in the late afternoon, we were reminded of just how big the snowpack was this year, and how big the flooding danger was. The road was being undercut by the surging river.

We had arrived in Yellowstone National Park! We didn't have much chance to explore, as the sun was nearly down, and our camp was on the other side of the park, at Madison. And Yellowstone is a big park. Our explorations would start in the morning...