Well... after a week in Parque Nacional Torres del Paine, it was time to head out of the wilderness and back to the relative civilization of Puerto Natales. We woke on the seventh day, and were pleased to see that the sun was hitting the Cuernos del Paine in a pleasing fashion:


Our tent in the foreground of the Cuernos del Paine:


We made our last batch of camp coffee and our last batch of oatmeal, and then started hiking out. As we walked along, we saw some interesting geology.

Here's a decent little weathering rind. Notice how the initially rectangular profile of this clast is being weathered towards a progressively more bread-loafy shape:


A small dextral fault offsetting turbidite layers:


Looking up into one of the valleys we passed on our way east, we saw an intact glacial end moraine sealing the valley shut.

I'm used to seeing these depositional features bisected by streams, but this one looked just like a wall built perpendicular to the valley trend. Erosion hasn't yet undermined it.

We arrived at the Torres area and fortified ourselves with Snickers bars dipped in peanut butter, then strolled on. There were a great many people there: somewhat shocking to the dirty backpackers...

As we hiked out from the Torres campground/village/tourist extravaganza to the entrance station at Laguna Amarga, we turned around and saw the Torres themselves, namesakes of the park, faintly through the misty distance:


Several kilometers on, we approached the Laguna Amarga Ranger Station, which is situated next to a lovely syncline in the Cerro Toro conglomerate:


Another view, from lower elevation, and closer to the axis of the fold:


Our time in Torres del Paine was unforgettable. Backpacking the Grand Circuit was a travel experience I would recommend to anyone with the ability and temperment to camp and hike in such gorgeous surroundings. It had been the primary goal of our trip, but we weren't done travelling yet. We headed back to Puerto Natales on the bus, and gorged ourselves on pizza that evening. We did laundry, got showered up, and slept like hibernating bears. In the morning, we boarded another bus, one that would take us across the border into Argentina...

Labels: chile, glacial landforms, national parks, patagonia, south america, structure, travel, weathering

You'll recall that our sixth day in Torres del Paine National Park had us hiking east from the Paine Grande Lodge. We hiked up over a ridge dividing Lago Pehoe from another turquoise-colored lake, Lago Nordenskjold:


At the so-called Italian Camp, we dropped our packs, and went for a small side hike. We turned to the north, and hiked up the French Valley:

The object of this day-hike was to see some glacier calving. The French Valley is famous for this: you sit back and watch, and big chunks of ice spall off the glaciers, crashing hundreds of feet below onto the rocks. A few seconds later, a sound like thunder reaches you: it was this that we came to experience.

Anybody seen a glacier around here? Rumor is that it was JUST here!

[The line demarcating vegetation above from bare rock below shows former height (and presence) of the glacier.]

Here's a look at the amphitheatre where our glacial show would be performed:


As the clouds cleared a bit, we could see an astonishingly thick cornice of snow/ice atop the mountain peaks. All the valleys up top had been filled in and smoothed off, and there was this white rim atop the black rock. The cornice is probably 40-100 feet thick in this photo:


An annotated photo of the area where we were observing the action:

What happened here was that a much larger glacier (see the vegetation line back a few photos) ablated away, splitting into two upper disconnected feeder glaciers, and a lower glacier which is now semi-buried in rocky debris (talus) and ice spalled off the upper glaciers.

A closer look at the annual growth layers revealed in the lower part of the glacier:


We soon saw some calving events. They were quite cool. Big booming noises, ice explosions seen through binoculars, eating chocolate and almonds. We were happy. Then we heard a roaring noise, like an airplane going overhead. We looked at the glaciers: nothing. What was making that noise? Then, from above, we saw it: coming down out of the clouds was a huge billowing white mass. Apparently, it was coming down from the cornice of snow atop the mountain. An avalanche! An honest-to-goodness avalanche! I have never seen one before; I was giddy at the spectacle. It looks just like a turbidity current, people, but it is white!

It was a magical thing to witness: watching it spread out and poof outward in hundreds of little round turbulent vortices. Everyone in the valley cheered: "YEAHHHH!!!!!"

Tough act to follow... but: Just east of us were the rugged Cuernos del Paine, a series of glacial horns made more photogenic by the pink stripe running through their middles, like a WWF Championship Belt:


This pink stripe is a granitic intrusion, approximately 12 Ma (Miocene*). Here is another photograph of the Cuernos, where the granite is very obvious:


We walked along the north shore of Lago Nordenskold towards the Cuernos campground...


Across the lake, some nice folds were visible:


The Cuernos campground is in this little nook. A lovely place to spend an afternoon and our final night in the park:


And it has very nice views of the Cuernos del Paine:


Seeing the Cuernos was the fulfillment of a decades-old dream for me. I think I saw them in an REI catalog (or perhaps a Patagonia catalog, hmm?) back when I was in college, and thought, "Wow. There's a place on Earth that really looks like that? I gotta go... someday." What I didn't expect then, and was pleased to see now that I was there, was the excellent evidence of stoping, one of the processes by which magma chambers enlarge their size and intrude into other rocks. Stoping is where chunks of the wall rock ("host rock" or "country rock") are broken off by inquisitive fingers of magma, and the liberated blocks (now xenoliths) drop into the magma chamber. Here, you can see (white arrows) some of these splurtles of granite working their way into cracks at the top of the magma chamber:


If these fingers of granite connect up, they separate the block of rock beneath them from the country rock (a form of physical weathering, like root wedging!). More dense than the surrounding magma, the resulting xenoliths sink. If the magma is still rather fluid, the xenoliths may now pile up on the floor of the intrusion. If it's getting to be mushy and semi-crystalline, their downward flow may be retarded, like a slice of banana trying to sink through thick oatmeal. As the granite crystallizes into rock, those xenoliths will be trapped somewhere between the ceiling (source area) and the bottom. Check out the diversity of xenolith positions (white arrows) displayed on this Cuerno:


Great looks at stoping here: some have fallen, some are still beginning to fall. I could easily have spent another two days just hiking along this contact, looking at this intrusive relations.

We spent our final night in the park enjoying the sounds of a nearby waterfall, nature's white noise machine. Only one more day in Torres del Paine...

Labels: chile, glacial landforms, glaciation, granite, ice, igneous, miocene, national parks, patagonia, south america, travel, weathering, xenoliths

The final segment of day 3 in Torres del Paine National Park was crossing through John Gardner Pass and heading down the other side, being treated to our first view of the Grey Glacier.

Here's me huffing and puffing up the final snowfield below the pass:


...And then we were there! This is the highest point on the Grand Circuit. An "iron woman" trail runner took our photo atop the Pass:


The surrounding scenery spoke very clearly of recent glaciation, like these horns:


And it was here that we first got a look at the immense Grey Glacier...


Annotated panorama shot of the Grey Glacier:
It is an impressive thing, this massive tongue of ice. Sourced in the South Patagonian Ice Field, the Grey Glacier is the largest in Torres del Paine, and effectively divides the Paine Massif from the main chain of the Andes (visible on the other side). I've noted a promontory of bedrock poking up through the ice (a "nunatak") at left, and the position of a tributary glacier at right. I was quite struck by the 'deflation' of the Grey Glacier, as marked by the disparity between the current top of the glacial ice and the line where vegetation begins.

A closer look at the tributary glacier:


Crevasses galore, and a 'blue hole' where a stream is feeding into the base of the glacier:


A few more shots. It's very photogenic. I don't have anything to say about these. Just enjoy:








Peaks of the Paine massif enconced in ice and snow:


We camped that night at Paso Campground. It was Christmas Eve, and we drank some Gato vino tinto and made a delicious fish stew for dinner. We went to bed at dark, but our campground neighbors did the European / South American thing by staying up late celebrating with one another. At midnight they sang their final song and drank their last swig of whiskey, and then there was peace and quiet... so at least half the night was silent!

Labels: chile, glacial landforms, glaciation, ice, national parks, patagonia, snow, south america, travel

Day 3 of our backpacking tour in Torres del Paine National Park (Chile) was an especially rich one. There's so much material to share that I'm going to divide the day up into three chunks: (I) the area around Los Perros Glacier, (II) the area on the east side of John Gardner Pass, and (III) the area west of John Gardner Pass, including the Grey Glacier.

We begin in Los Perros. As you will recall from our last installment, Lily and I had put in a long day of hiking, essentially pulling double duty by hiking all the way from Seron to Los Perros, and skipping Dickson in between. Because the park only allows camping in certain designated areas, trekkers are often put in the position of either hiking less than they want on a certain day, or more than they want. Day 2 was more than we wanted. We slept heavily, and woke to a drier world. We made coffee (we tried out those new Starbucks "Via" instant coffee packets on this trip and found them reasonably acceptable) and decided that before the day's slog, we should backtrack a bit to the Los Perros Glacier and check it out in more detail. As we were hiking in to camp the previous evening, we only had a 5 minute window of decent weather to view the glacier and its surroundings, so we wanted to see what we had missed.

It was a good call. I really enjoyed poking around there. To start with, check out this perspective view down the valley we had hiked up the previous day, the horseshoe-shaped glacial moraine, and the gray-colored glacial lake backed up behind the moraine:


A closer look at the till making up the moraine:


...And in another direction, too:


Composite stitched together of the moraine-dammed lake, using both of the previous two photos plus three others:


Looking down the axis of the lateral part of the moraine (perspective is towards the glacier, though the ice itself is hidden by the bedrock ridge):


"Lil on till":


We walked towards the glacier, checking out the accumulation of icebergs up against the moraine:


A closer look at the terminus of the glacier:


It was a cool place to look at rocks, too. Everything was so fresh, since the glacier had so recently scraped them clean. In this photo, looking across the lake, you can see the line where the vegetation abruptly stops, showing where the glacier was until relatively recently, when it receded to its present position.

A little lateral moraine clings to the walls of the valley. Where it has been eroded away, you can see details of the bedrock, like the granite dike visible on the left.

If you look carefully in this photo, you will see a large vertical granite dike. Follow along in the direction I am pointing. Hopefully you will be able to find it:


This dike continued out into the space where the glacier eventually carved the valley where the lake now sits. But in the middle of the lake is an island, and right along strike from the big granite dike, you can see a granite dike cutting across the rock of the island:

I'll bet it's the same one.

These dikes had some cool details revealed in the area around Los Perros Glacier. Here's an explosion of dark xenoliths in one intrusion. This is clearly intrusive, because it cuts across several turbidite layers, but I was confused about the texture. I expected granite, but it really looked kind of like... sandstone.

I know there are some clastic dikes in the area, and this may be one of them. I've never seen clastic dikes before, but I guess this is what I would imagine they would look like.

...and how about this???

I think that's two clastic dikes cross-cutting a turbidite bed. A nice relative dating exercise, eh?

Some Z-folds reconfigure quartz-filled tension gashes:


I also found a cool little chunk which showed a nice set of concentric ribs:


Classic slickenlines, lacking those gaudy crystal fiber lineations you usually see on fault surfaces. This is gouging, pure and unadulterated and simple:


Such geological goodies! It's better than instant coffee for perking a fellow up in the morning hours. Energized and invigorated, we headed back to Los Perros Camp for our packs, and hit the trail, heading further up the valley. More on that in part II!

Labels: chile, glacial landforms, glaciation, granite, igneous, patagonia, primary structures, sediment, south america, structure, travel, xenoliths

Yesterday, I asked you to figure out what I was getting at here:


The answer is that I was trying to depict the fundamental difference between the two different classes of glacial landforms by showing the two different actions glaciers can take on rock: either they can carve it up, or they can carry it off a ways and dump it.


Glacial landforms may be broadly grouped into erosional landforms (like cirques, aretes, horns, and hanging valleys) and depositional landforms (such as moraines, eskers, drumlins, and kettles). Erosional landforms dominate in areas of alpine glaciation (like, say, the Patagonian Andes). Depositional landforms dominate in areas of continental glaciation (like, say, Wisconsin).

If any educators want a full-size (i.e. PowerPoint-ready) version of this image, shoot me an e-mail. I'll send you one, and I won't do so at a glacial pace.

Nobody really guessed it. But there were some great guesses regardless, and perhaps the big lesson is that the Analogy Is In The Eye Of The Beholder. Thanks to all who contributed ideas to the discussion!

Labels: analogies, art, contest, geomorphology, glacial landforms, glaciation, graphics, patagonia, wisconsin

OK, time to start showing some photos from this winter's trip down to Patagonia. Today, I'll talk about our journey south from Puerto Montt, Chile, to Puerto Natales, Chile. We took a ferry, the M.V. Evangelistas, operated by Navigaciones Magallanes, better known as Navimag. We flew through Santiago, and had to spend a couple hours laying over in that airport. During that time, we checked out this tower of luggage that had been set up in an otherwise-unused space:



Black-fronted ibis (see full bird list here) in Puerto Montt:


The Evangelistas in port, prior to our departure:


Steaming out of Puerto Montt, we got good looks at two volcanoes. The smooth white one on the left (north) is Volcan Osorno, and the craggier one on the right (south) is Calbuco:

Heavy cloud cover prevented us from seeing Chaiten the next day, which was a bummer considering all the press it got for its eruption in 2008.

A few shots to show the scenery typical of the next three days as we sailed south towards Puerto Natales:










A ship that ran aground in the 1960s:


We passed a lot of the time in birdwatching. Peering over the deck with binoculars pressed to your eyesockets is a good way to attract other birders. So we made friends with Rory and Leann, a South African couple on a month-long tour of South America. That's Rory in the red jacket:


Doing this, I saw my first penguin, dozens (hundreds?) of albatrosses, and the flightless steamer duck, which is, as Rory enthusiastically pointed out, "a f#%king flightless duck!"




When I see a new species, I note the date and location in my bird guide:


One day, we made a detour to go check out the "Pio XI" or Bruggen Glacier draining into the ocean from the South Patagonian Ice Field (fourth largest ice sheet in the world, after Antarctica, Greenland, and the Elias-Kluane ice field in Alaska and Canada). The Bruggen Glacier is the longest in the southern hemisphere, outside of Antarctica. It is the largest glacier in South America. And it is named for a Chilean geologist!


Here's a satellite view of the area, courtesy of NASA's Earth Observatory:

On the way over to the glacier, we saw the first iceberg of the trip:

Note all the sediment in that ice: it's dirty stuff!

Getting closer:


Closer still, and a medial moraine becomes visible as a dirty stripe running through the middle of the glacier:


Happy tourists:


Continuing south, we encountered more and more islands, and in many places the channel through which the Evangelistas sailed was quite narrow.




At one point, we squeezed through this NARROW gap:


Finally, we approached Puerto Natales, a small town that serves as the main access point for Torres del Paine National Park:


Looking in the opposite direction, I was pleased to see a broad syncline screaming out from the mountainside:


More on Puerto Natales this weekend...

Labels: birdies, chile, glacial landforms, glaciation, mountains, oceans, patagonia, satellite imagery, south america, structure, travel, volcano

Just got back to DC, and I'm pleased to report that I had a great trip. I hope you enjoyed the posts I set to publish automatically in my absence --- just like I was never gone! You'll be hearing much more about my time in Patagonia in the days to come... ...but for now, here's one image to whet your appetite:

Labels: chile, clouds, glacial landforms, mountains, patagonia, travel

Yesterday, I showed you these photos...



...and asked you to guess what they reminded me of.

Man, there were some great ideas people pitched forward! I was really impressed. One person even came up with the same idea that occurred to me!

Okay, so clearly what we've got here is a puddle that's drying up right? Some leaves and other botanical debris fell into the puddle and has thus become concentrated in this spot.

The pattern I noticed was a linear pile of debris [consisting mainly of the woody little "petals" of the tulip tree (Liriodendron tulipifera) "flower"] as well as a dark color due to being damp. The edge of the damp patch parallels the edge of the linear tulip tree debris field. I think the way this formed was that in the puddle's earlier (larger) state, it was deep enough for the tulip tree "petals" to float, and wind pushed them all over to the same side of the puddle (the southern edge). As the puddle dried out, this stranded flotsam preserves either an earlier "shoreline" or an offshore parallel to the shoreline. (The second possibility would apply if the "petals" were too big to get pushed all the way to the actual shoreline: they may run aground some distance "offshore.")

This brought to mind the relationship between a continental ice sheet and the end moraine it leaves* behind. Glaciers expanded outward, reach their maximum size, stay there for some amount of time, flowing along and depositing a scum of debris all along their edges. Later, they melt back, or possibly melt away entirely. However, the debris belt marks how far out they once reached. Here's a geological equivalent, in a map** showing end moraines (green) in Minnesota, Iowa, and South Dakota:


As the moraine marks the former extent of the glacier, so too does the stranded line of tulip tree flotsam mark the former extent of the puddle. Fresh from my lectures on glaciation and the Ice Ages, I got the sense I was looking from west to east across North America, seeing Canada recently scraped clean (wet areas) and the far-right ("south") accumulation of tulip tree petals morphed in my mind into a terminal moraine complex.

The main problem with this analogy: puddles are standing water, not flowing ice. Still, I can't help but see a similarity in process, regardless of the huge differences in scale and materials. I see the world through geology-colored glasses.
_______________________________________
* no pun intended
** From the U.S.G.S.'s "Glacial map of the U.S. east of the Rockies, west half" (1959)," via here

Labels: analogies, contest, glacial landforms, glaciation, iowa, minnesota, nova, plants, south dakota

As noted earlier, I had the good fortune to spend last week in Yosemite National Park, celebrating the wedding of my friends Jason and Lindsay, and in general poking around in one of the coolest places around. Below, a summary of the three-day trip:

Friday:
Lily and I flew to Modesto, California, and rented a car. It took about two hours to drive up to Evergreen Lodge, where we checked in and then headed out for a short hike in the Hetch Hetchy area. Hetch Hetchy was dubbed "Yosemite's sister valley" by John Muir in an attempt to keep it from being dammed. But the city of San Francisco had been destroyed in 1906 by earthquake-induced fire, and the call for a reliable water source was an important force in overpowering Muir's conservationist ideals. Ken Burns apparently explores this saga, the first instance of "development vs. conservation," in the second episode of his new National Parks series. (I saw the first episode, but haven't caught up on the rest of it yet.) The valley was dammed in the 1920's, creating the Hetch Hetchy Reservoir:


Here's the O'Shaughnessy Dam, named after the chief engineer of the project:


I didn't find it as spectacular as Yosemite, but it was sure a pretty place. Walking along the north side of the reservoir, I reaquanited myself with some fine Sierran granites and granodiorites. Here's a sweet little xenolith (or maybe an MME; how can you tell an MME from a mafic xenolith?):

Back to the Evergreen for the rehearsal dinner (Oktoberfest theme!) and then bed.

Saturday:
Up early, got some coffee, drove an hour to reach the Yosemite Valley. I liked how quiet things were compared to the throbbing pulse of summer. This view of El Capitan, for instance, is typically mobbed with tourists. This day, we had it to ourselves for five minutes or so, then shared it with one other car:


Time to stretch the legs! We decided to hike up to Vernal Falls. On our way up, the base of the falls was still in shadow, with low-angle morning sunlight dramatically illuminating the upper reaches of the falls:


Looking back down the valley we had climbed up... I like the dark shadow of the cliff merging with the dark shadows of the trees below:


But if we set the camera's F-stop a bit differently, we can see what's going on in all that shadow. There's the trail we climbed up, with fellow hikers for scale:


Up top, photographing the waterfall:


On our way back down, with more of the falls illuminated as the sun rises in the sky:


Looking north across the valley from where we parked our car, marvelling at the huge exfoliation joints there: rounding these exposed plutons into granite 'domes.'


... or Half Domes, as the case may be:


A view from further out, again with Half Dome the most striking landform:


Then, we headed back to clean up before the wedding. Great ceremony, amazing meal. Drinks, dancing, rhubarb jam, bluegrass, reminiscing with old friends and new. Ahhh.

Sunday:
Breakfast and coffee with the wedding party, then off to check out some big trees. We drove to the Tuolumne Grove of giant sequoias. It started snowing on the way there, but we didn't let that deter us. On the hike down from the parking area (where, by the way, they had closed the Tioga Road), we found this nice example of spheroidal weathering in an outcrop of granite:


But the real attraction was the enormous sequoia trees. Here's one:


And a dead one, with a car-sized hole cut through it:


I found these trees very impressive: they were just stunning in their grandeur and immense age. Snow continued to fall as we left. We had to get going to make our flight home. Somewhere on the way down the mountain, Garry Hayes and his wife passed us going up the mountain. Ships passing in the night -- sorry I missed you, Garry! We made a couple of roadside outcrop stops, then got back to Modesto and traded in the car for an airplane. Our "redeye" route back to DC took us through San Francisco and Los Angeles, and I ran into Thomas Friedman in the airport. Got back to BWI at 6am, and headed off to work...

Labels: california, glacial landforms, national parks, plants, travel, tv, water resources, xenoliths

My friends Jason and Lindsay had the good sense to get married in Yosemite this past weekend. So I enjoyed visiting the park, including some new places I hadn't been before, as well as the nuptial festivities. More later...

Labels: california, glacial landforms, national parks

Here we have some nice little glacial striations exposed in the Grinnell Glacier cirque in Glacier National Park, Montana. These grooves were carved by pebbles and other clasts within the glacial ice as it flowed over this outcrop of the Mesoproterozoic Helena Formation (part of the Belt Supergroup). Perhaps some of the same pebbles you see in this photo were responsible for acting as carving tools -- though the 'hand' that wielded them, Grinnell Glacier itself, melted away from this point sometime since 1939.

Also of interest to me in this photo is the lingering stain of water around the joint set in the upper right. I'm fascinated at the interplay between physical and chemical weathering, and seeing stuff like this emphasizes how even a simple hairline fracture can help funnel water, with all its destructive effects, deeper into the heart of an outcrop. Weathering is focused on these areas, and in another century this outcrop may look quite different.

Labels: glacial landforms, glaciation, joints, montana, national parks, pleistocene, proterozoic, sediment, snow, weathering

Part 1 and Part 2 of this series described the journey up from Jenny Lake to Hanging Canyon. Today, we pop up over the threshold of this hanging valley and see what we can see...



As it turns out, there's some snow up there:


We manage a few clumsy glissades:


And what's going on with this hole?


Aha! A dark rock with low albedo absorbs energy from the sun, releasing it as heat and melting the surrounding snow. Cool!


Times like this, I just love my job:


Ken shows off some glacial striations on the bedrock:


Pointing in the direction of glacial flow:


We then opt to climb up even higher, to peer down into the neighboring valley, the much larger Cascade Canyon...



Steep climb, with tarn in the background; Joel appears to be enjoying himself:


Here's a Google Maps "terrain" view of the area, showing the relative locations of Jenny Lake, Cascade Canyon, and Hanging Canyon.


Wow... Once we got up over that last little knife-edge crest, we had a pretty amazing view.


And what did we see along the way? More on that in tomorrow's post (Hint: pegmatites and old folds)...

Labels: glacial landforms, glaciation, national parks, snow, travel, wyoming

Today, picking up where we left off yesterday, some images from the hike upwards from Jenny Lake to Hanging Canyon...

Joel and Ken take a breather:


The approach to the final lip of Hanging Canyon:


A view down over Jenny Lake and Jackson Hole:

Jenny Lake is dammed by an end moraine (which is characterized by pine trees growing on it here, making for a nice dark stripe around the lake).

We could also see across Jackson Hole to the Gros Ventre valley, where the Gros Ventre lanslide scar was readily visible:


...And lastly, the view to the north, over Jackson Lake (with String Lake in the middle distance):


More tomorrow about what we found once we got up into Hanging Canyon itself... (Hint: it's white and cold and fun to ski on...)

Labels: glacial landforms, mass wasting, national parks, nova, travel, wyoming

All photos in this post by Rockies student Charlie Corrick.

Obstacle in the road...


Tetons...


Charlie and Jared on Blacktail Butte:


Luke on Blacktail Butte:


Charlie, Luke, and Jared on Blacktail Butte:


Checking out the fault scarp of the Hebgen Lake Fault, north of Hebgen Lake:


Examining the Grinnell Formation for the first time:


Looking down the St. Mary Valley, Glacier National Park:


Stromatolites in the Helena Formation, Glacier National Park:


Victoria points out the contact of the Purcell Sill with the surrounding Helena Formation (limestone), Glacier National Park:


Callan points out the contact of the Purcell Sill with the surrounding Helena Formation (limestone), Glacier National Park:


Pete and Joel point out the contact of an apophysis of the Purcell Sill with the surrounding Helena Formation (limestone), Glacier National Park. Notice that the sill cuts across stratification down by Joel's legs.


At the Bozeman Airport on the way home, John entertains us with geology songs he composed, which cracked up the instructors:

Labels: glacial landforms, montana, national parks, nova, proterozoic, travel, wyoming

All photos in this post by Rockies student Charlie Corrick.

Talking S-folds, vergence, and Pumpelly's Rule in the Bridger Range:


Hiking uphill and down-sequence in the Bridger Range:


Describing the Kootenai Formation:


Jared gets eaten by Big Mike:


Joel with a few columns of basalt:


Post-M.O.R.-tour, with the guide:


Victoria and a Triceratops horn:


Group at M.O.R., with Tyrannosaurus for scale:


Calcified bat, Lewis & Clark Caverns:


Inside the cave:


Beartooth Plateau:


Amanda enjoys the view:


Camp at Pebble Creek in Yellowstone:


Watching for wolves, Yellowstone:


Bison:


Obsidian at Obsidian Cliff:


Longhorned beetle that landed on our geologic map of Yellowstone:


More to come...

Labels: arthropods, dinosaurs, fossils, glacial landforms, mammals, montana, wyoming, yellowstone

Working through my backlog of e-mails, I find that I have a few more Rockies course final projects to share with the world:

Laurie's website on Yellowstone geothermal features.

Jared explores Ringing Rocks.

Kevin suggests "more study is needed."

Ken discusses Grinnell Glacier:

Amanda reviews the Tetons:

Labels: glacial landforms, glaciation, montana, mountains, stromatolites, volcano, water resources, wyoming

Labels: glacial landforms, glaciation, new york, sediment, travel

Labels: california, glacial landforms, mountains

One of my students, Rob M., forwarded this photo to me over the weekend:



He tells me his dad took it along the coast of Alaska. Pretty cool shot. Unlike most of the photos on this blog, you can click through to get a big version.

Thanks to Rob and his dad for permission to share the photo here!

Labels: alaska, glacial landforms, glaciation

You must see this!

Labels: glacial landforms

As you'll recall, when I left off with my Ecuadorian travelouge, Lily and I had summited Pasochoa, and then taken a day-hike in Cotopaxi National Park. Next up, a new mountain that has about the same elevation as Mt. Whitney (highest peak in the lower 48 United States): about 14,500 feet. To climb this extinct volcano called Ruminahui (Roo-min-ya-wee), we headed up a ridge between two adjacent glacially-carved valleys.















Me with clouds and background glacial valley:


Diego (our guide) on the trail:


Up on top, there was less vegetation, but more cloud... and snow was falling.

The bedrock was a volcanic breccia that had been cut by numerous andesitic dikes:






You can see some blurry snowflakes in the previous photo. Here's a cold-looking Lily with her boots on an andesitic dike:



Here's a couple of close-ups to show the cross-cutting relationships between the andesite dikes and the volcanic breccia:





Here's a short, not-especially-great video wherein I point out a few things that don't really show up all that well. Still, you get to see it snowing!

A big "thanks" to NOVA's king of digital video, Richard Attix, who helped me rotate this video and crop out some unintended footage from the raw video we shot on the mountain that day.

Cold hikers:



"Sheesh! It's cold up here!":



On the way down, we also took some time to check out the plants. Here's one called "Orejas de conejo" ("Ears of the rabbit"):

Here's one that smells exactly like chocolate!


In fact, Lily was able to harvest this chocolate bar from it!

Okay, not really. It's money that grows on trees, not chocolate bars.

So that's the story of our second successful summit... now there was only one more to go... the legendary Iliniza Norte. Photos from that hike in a couple of days...

Labels: ecuador, glacial landforms, mountains, plants, sediment, south america, travel, volcano

A bill working its way through the Senate right now, S-22, has some provisions you may be interested in. It's called the Omnibus Public Lands Management Act of 2009. Mainly, it sets aside a heckuva lot of wilderness areas. But the thing that brought it to my attention is that it sets aside some money to develop a "national geologic trail" focused on Glacial Lake Missoula, with an interpretive center to be located in Missoula, Montana. The Senate website describes it like this:

The Ice Age Floods National Geologic Trail Designation Act (S. 268 and H.R.
450), would create a trail to document the catastrophic flooding that stretched
across parts of Montana, Idaho, Oregon, and Washington during the last Ice Age.
The designation of an Ice Age Floods Trail follows the recommendations of a 2001
study headed by the National Park Service which found the area suitable for
addition into the National Park System.

This part of the bill carries a possible pricetag of $12 million, with $2 specifically for the visitor center. Though there's no way the trail would be done by this summer, Glacial Lake Missoula's geologic signatures will be some of the highlights planned for this summer's Regional Field Geology of the Northern Rockies class.

Read more about it in this article in the Missoulian.

Hat tip to Babak R. for letting me know about this.

Labels: glacial landforms, glaciation, lakes, montana, national parks, politics

What's the tallest mountain on Earth?

Everest, right? Well, yeah: if you're measuring from sea level. If you're measuring from the top of the crust the mountain rises from though, it's Mauna Kea, Hawai'i. It's about ~13,800 feet above sea level, but it rises ~33,500 feet from the oceanic crust to the peak (that's compared to Everest's mere ~29,000 feet from base to peak. So... you could say that Mauna Kea is the tallest mountain on our planet... (you could!)

On Thanksgiving day, my friend Lily and I took a drive up to the top of Mauna Kea, and did a little hike up there at high elevation. Today, I'd like to share some photographs of that excursion. We saw some pretty cool geology.

On the drive up the mountain, we saw an animal which was apropos, considering the day:

Gobble, gobble, gobble. Watch out turkeys, we'll be back after we work up an appetite...

Here's Lily's jeep in the "saddle" between Mauna Kea and Mauna Loa, looking north (with Mauna Kea in the background and basaltic lava flows from Mauna Loa in the foreground):


Some cider cones (the Hawai'ian word for cinder cone is pu'u) in the saddle:


Turning the other way (looking south), you can see the bulky form of "the long mountain," Mauna Loa. What a classic shield volcano shape! I love the fact that it's so dang wide it makes a lousy photograph. You just can't capture its spread-out bulk in a photo; it's too massive:


This was the spot where I pretended to have my toes overrun by a pahoehoe flow:


As we drove up the road to the top of the mountain, I was amazed at the raw volcanic landscape, decorated with cinder cones like this one:


At one point, we passed a neat little angular unconformity on the roadside. Here it is, with a nickel (white dot left of center) for scale:


Here's a closer-shot of this small angular unconformity. Earlier layers of ash and lapilli were deposited at a steep angle, and then eroded (perhaps by glaciation? pure speculation there) before more ash and lapilli were deposited atop it, at a lower angle. There's not likely to be much time missing here, and so perhaps it's better to think of this as the top of a cross-bed, an advancing front of pyroclastic deposition moving down the mountainside, overrun by later eruptions, which may have scoured off the upper few inches (??? pure speculation) or so before deposition.

Really, the truncated tops of cross-beds are mini-angular-unconformities, when you think about it; just not with the same amount of time missing at a "real" angular unconformity (with millions of years missing) due to mountain building like the one at Siccar Point. (Video of cross-beds forming)

Here's something else which the clueless geologist might mistake for a sign of mountain building:
No, those aren't originally-horizontal strata that have later been folded. They're layers (again of ash and lapilli) deposited on the originally-rough topography of the mountainside, covering small ridges and filling small valleys. Where a given layer is exposed at higher elevation, I interpret to be a paleo-topographic high; where that same stratum is exposed at lower elevation, that's a paleo-topographic low. The roadcut reveals these layers have undulating shapes, but this is unlikely to be folding that results from tectonic compression: instead, I think it's showing us the lay of the ancient land surface.

Looking south, we could see past Mauna Loa to the actively erupting steam vent coming out of Halemaumau Crater at Kilauea Caldera (source of the vog!):


Near the summit of Mauna Kea, there are a bunch of astronomical observatories:






On the summit is where you find those examples I mentioned the other day of hawaiite, a rock of basaltic composition that is very dense (ostensibly due to erupting beneath the extra pressures of a Pleistocene ice cap):


Here's me on the summit:


View to the north from the summit: More cinder cones...


Here's a YouTube video of me pointing stuff out from the summit (Kilauea, Hualalai, Mauna Loa, observatories, hikers, etc.). Unfortunately the wind makes it all but unintelligable, but I filmed it, doggone it, so I'm going to post it:



I found a beautiful example of a volcanic bomb up there:


After the visit to the summit, we went for a hike to a small supposedly-glacially-gouged-out lake below the summit (Lake Waiau):


Here's a Google Map, showing the lake's location:


I was surprised to see a thick biofilm on the bottom of the lake:


Encrusting the pebbles and cobbles there, it reminded me of Nora Noffke's modern and Archean biofilm photos in the recent GSA Today, as well as my "Life in Extreme Environments" class this past summer at Montana State University.


We saw some nice examples of structural geology on this hike. Previously, I've mentioned plumose structure, a branching pattern on the topography of fracture surfaces in fine-grained rocks. We saw some of that on blocks of basalt atop Mauna Kea, as in this example (again a repeat photo, but the other day I showed it to you for the vesicle; today I'm showing it to you for the plumose structure.)


A similar feature are arrest lines, which again are minute variations in the surface of a fracture. Like plumose structure, which branches from a source point (where the fracture initiated) and branches out in the direction of propagation, arrest lines tell us about the development of a joint. Unlike plumose structure, though, they are not parallel to the propagating fracture front. Instead, they form perpendicular to it, and record how the fracture propagates in small "steps." Each of these arrest lines is interpreted as being a spot where the fracture grew a little bit, then stopped ("arrested") and then grew some more. In this case, the fracture face we're looking at started at the bottom of the picture and grew towards the top of the photo. You can even see some less-discernible plumose structure backing this up:

Similar arrest lines can be seen in basalt images here and here...

We also saw some pretty spectacular xenoliths. Here's one of gabbro in basalt:


Here's one of peridotite in basalt:


And a few more:



My boots, with another volcanic bomb:


Driving back down the mountain afterwards, we got this nice view of the cinder cones (pu'us!) in the eastern part of the "saddle" between Maunas Kea and Loa:


This Mauna Kea excursion was one of my favorite things that I did on my all-too-brief trip to Hawaii. It was great to get up in the high country, where the air is thin (and vog free!) and the skies are deep blue, and the geology is surprisingly varied (at least it was surprising to me, and pleasantly so). The hike let us work up a good appetite, so we headed back down the mountain and straight to Thanksgiving dinner!

Labels: basalt, birdies, geology, glacial landforms, hawaii, igneous, mountains, msse, primary structures, structure, travel, unconformities, volcano, xenoliths

Here's how I explain the carving of horns as erosional features of glacier geomorphology:








Once you've scooped into the pint of ice cream and out (away from the frozen core towards the thawed exterior), you end up leaving a pinnacle in the middle with curved facets ("cirques"):


... Kinda like this:

Labels: analogies, geology, glacial landforms, teaching

This image came to my attention the other day via Lutz's Geoberg blog. It's one of the high-res images provided by the newly-launched satellite, the GeoEye-1, which is supplying new images to Google*. The image shows a marginal lake associated with an alpine glacier in Kenai Fjords National Park, Alaska (just south of Seward):


The top of the above image is not north; it's southwest. Mentally rotate it, and you can see that the resolution is a lot better than the current level on Google Earth and Google Maps:


The thing that struck me about the new GeoEye image, aside from its beauty, is the distinct pattern of iceberg sizes in the lake: freshly calved off the glacier, the biggest icebergs are close to their source, while further away the icebergs are smaller. This pattern struck me as being analogous to sediment. Fresh from its source, sedimentary particles are at their largest size, and the further away they travel, the more weathering they experience. This weathering (in particular of the physical variety) tends to break them down into smaller pieces. Adjacent to an orogenic belt, for instance, you tend to find deposition of sedimentary particles shed off the uplifting mountains. As a general rule, these are of the largest sizes and the greatest volume closest to the source, and then particle size and stratum thickness both diminish with increasing distance from the orogen.

For a North American example, consider the Catskill Clastic Wedge, a tick pile of sediments shed off the late Devonian Acadian Orogeny along the east coast. Here's a cross-sectional view** (pre-Alleghany Orogeny deformation) of the wedge, running from the Bay of Fundy west to Michigan:


Same pattern! Coarse stuff, and more volume of stuff, close to the source. Finer stuff, and less volume of stuff, further from the source. Just like the iceberg, except the weathering of the icebergs is mainly thermal, while the weathering of the sediments is physical, accompanied by depositional sorting by the transporting currents of water.

__________________________________

* An original version of this post misidentified Google as the owners of the GeoEye-1, as opposed to the company called GeoEye, which sells images to Google. Thanks to Bruce Haley for the correction. (updated 8:14AM eastern time on Dec. 9, 2008)
** Image redrawn (by me) from an original in Prothero & Dott (2003).

Labels: alaska, analogies, art, canada, glacial landforms, glaciation, maine, michigan, mountains, new york, satellite imagery, sediment

Dave at the Geology News blog is hosting this month's Accretionary Wedge on the topic of "favorite places to do field work."

My favorite place to do field work is in California's "range of light," the Sierra Nevada.

I did my geology master's field work in the eastern Sierra, along the Sierra Crest Shear Zone, a major high-strain zone which parallels the eastern edge of the Sierra Nevada Batholith through older meta-sedimentary and meta-volcanic host rocks.

In 2003, I spent the summer out there, starting with my first field area at lovely Gem Lake:

An angular unconformity can be seen in this image as the tilted (close to vertical) metasedimentary and metavolcanic rocks (orange and gray) are overlain by dark colored "Tertiary" basalt flows. A big talus slope of basalt chunks makes a black triangular shape that heads downhill toward the lake. In the distance, where the land rises appreciably, the granites (and granodiorites) of the batholilth begin.

We camped on this peninsula sticking out into Gem Lake:


Dazhi Jiang (Then of UMD-College Park; now at the University of Western Ontario) and USC's Geoff Pignotta examine strained metavolcanics near Gem Lake:


Here's me with the Ritter Range in the background:


Glacial striations sculpting my strained metavolcanics:



Field gear:

Labels: california, field trips, glacial landforms, granite, igneous, metamorphism, structure, travel

Here's a couple of more photos from my travels out west this summer. This is in Jackson Hole, the large valley that abuts the Teton Range immediately to the east. If you've never been to the Tetons, you must go and check them out for yourself. They are an awesome, singular mountain range in the United States. Their shapes and sheer relief remind me of the Karakoram, or Torres del Paine, or some other awesome mountainous region of the world. It's really jaw-dropping.

Here's a shot of the Tetons from the northeast, visually pairing them with a line of coniferous trees in the foreground. Photographically, I like this parallelism in their shapes:



So what's up with the Tetons? What geologic processes give rise to their readily-apparent awesomeness? There's two main things going on here: faulting and glaciation. First, there's a major normal fault along the base of the range. The Tetons have moved up as a block while the Jackson Hole basin has dropped down as a block. As the rocks of the Tetons (some as old as 2.8 Ga) have been eroded, sediment was generated, and that dropped down to fill in the hole to the east. Jackson Hole is full of of sediment (over 20,000 feet deep), and then the peaks of the Tetons rise an additional 7000 feet beyond that. Based on offset of the Cambrian Flathead Sandstone on either side of the fault, total displacement is estimated to be 30,000 to 35,000 feet (Love, 1987). Even relatively young geologic units in Jackson Hole, like the Yellowstone-erupted Huckleberry Ridge Tuff (2.1 Ma), dip significantly towards the fault (Good and Pierce, 1996). Movement along this fault is ongoing, raising the mountains on average ~1 centimeter per year, with most movement having taken place over the past 9 million years. The Tetons are generally regarded as the youngest range in the Rockies.

Here's a shot coming north from the Gros Ventre landslide area (subject of a future post) towards the main road. A photogenic herd of bison was grazing on the grassy sagebrush flats, purposely maneuvering between me and the mountains so they would have a nice backdrop:



Once the Pleistocene ice ages began, the tall Tetons accumulated a lot of snow, which packed into glacial ice. Alpine glaciers started flowing downhill, and carving the rock of the mountains as they did so. That created the distinct U-shaped valleys seen in these photos, and left pointy little nubbins between them: the glacial horns like the Grand Teton and Mount Owen. The rocky debris scraped off the Teton block was deposited in Jackson Hole along with till from the Yellowstone ice cap to the north. These piles of glacial till are easily demarcated by the coniferous trees that grow on them, unlike the grasses and sage of the outwash plain.

References:

Good, John M., and Kenneth L. Pierce (1996). Recent and Ongoing Geology of Grand Teton and Yellowstone National Parks, Grand Teton Natural History Association, Moose, Wyoming, 58 pages.

Love, J. David (1987). "Teton mountain front, Wyoming." In: Geological Society of America Centennial Field Guide - Rocky Mountain Section, Stanley S. Beus, ed. Geological Society of America, pp. 173-178.

Labels: faults, geology, glacial landforms, travel, wyoming

Here's a quick recap of my cross-country journey, for those who are interested in such things.

I left Bozeman on Saturday morning, July 26, and drove east on the Interstate to Billings, then diverged southeast towards Little Bighorn. There, I verified a comment from a Lakota friend at MSU that with my new bushy mustache (see change in icon above), I look a wee big like George Armstrong Custer (Custer & his men were killed by Lakota and/or Cheyenne warriors). After a short picnic there, I kept driving across southeast Montana, and into northeast Wyoming. My goal for the night was Devils Tower, where I have positive memories from my "North by Northwesty" roadtrip two years ago. I got to Devils Tower in mid-afternoon, just in time for a wicked-looking thunderstorm to roll in. Pendulous looking mammatus clouds were hanging down, and the skies turned a darker grey than Lola. Rain and wind came through, and a big dead branch from one of the cottonwoods in the campground came crashing down, but not on anyone's car or tent. When the skies cleared up, I drove up to the visitor's center and took a walk around the tower. It's awesome: massive columns, some of them twenty feet across. The rock is a porphyritic phonolite, and it's quite pretty to look at: big feldspars (5mm) set in a fine-grained grey matrix. Lovely.

The next morning (Sunday), I headed for Red Bird, Wyoming (along Wyoming's eastern border), where Cruisin' the Fossil Freeway suggested there would be oodles of ammonites in concretions in the Pierre Shale, some a foot across. When I visited the Denver Museum of Nature and Science earlier this summer, Kirk Johnson reiterated to me that Red Bird was the place to go for ammonites. But once I got to where Red Bird should be (according to my road atlas), there were no highway signs indicating that the town existed. Worse, there were no outcrops, and no sign of public land. (And one thing that an amateur fossil collector does not want to do in Wyoming is trespass on a rancher's land.) So, no Red Bird ammonites for me. Oh well, no worries: I had collected ammonites from a tongue of the Pierre Shale (the Bearpaw Shale) earlier in the summer on BLM land near Glendive, Montana, and scored some good specimens there. I cruised south, stopping at the Sierra Trading Post outlet in Cheyenne, Wyoming, and dropping some cash on some new duds (STP is mainly a catalog business, famous ten years ago for their amazing deals, but the company seems to be shifting to more mainstream business nowadays, including multiple brick-and-mortar locations). Then another hour on the road brought me to Fort Collins, to the house of Larry Wiseman, where I stayed earlier in my trip. He and I got some pizza and 90-Shilling Ale (Odell's) and traded tales about our summers.


The next morning, we had coffee on Larry's front porch and watch the sun rise. I packed up and hit the road, heading for Kansas. In my rear-view mirror, the Rockies shrank and vanished from sight, a melancholy fade. Out into the plains... In mid-afternoon, I rolled into Oakley, Kansas, where I headed for the Fick Museum. The Fick Museum is interesting on multiple levels: it's got some stellar fossils from Kansas's Smoky Hill Chalk (member of the Niobrara Formation), like a Xiphactinus (massive fish) and a Tylosaurus skull (even more massive mosasaur). But it's also got some whacked-out art: the founder, Vi Fick, was into making art with local "art supplies," and so the walls show his portraits of eagles rendered entirely in rattlesnake tails (see image at right, from this online gallery), or his geometric arrangements of thousands of fossil shark teeth. There's even an oil painting Fick did of "God making the Cretaceous seas," which shows a bearded diety surrounded by flames (it kind of reminded me of Hindu art) making pleisiosaurs and pterosaurs. Not the usual way you see fossils displayed, or paleontology depicted!

At the Fick Museum, I met up with Ron Schott, doyen of the geoblogosphere, who graciously agreed to show me some cool Kansas geology. Ron and I headed south from Oakley towards Monument Rocks, an outcrop of the Smoky Hill Chalk. Ron was eager to gigapan the outcrop, and he set up the little device: essentially a robot that directs his camera to take high-resolution photos in a systematic grid. Pretty cool, really -- I guess I hadn't realized what a Gigapan really was before seeing it in action. I got to meet Ron's two little plastic elves that he uses for scale, and personally placed them on a ledge of chalk for the photograph. The grid of pictures eventually gets digitally stitched together by software, and available for sharing online.

From there, Ron and I headed back up to Oakley, stopping en route so I could collect a couple samples of the aquiferiferous Ogallala Formation, and then headed east, then south again, towards Castle Rock, another chalk outcrop. Here, we tested out my Prius' shocks on the dirt tracks, and checked out the largest cliff in Kansas (nearly getting blown off it by the intense wind), and then prospected for fossils below. I found some fish scales, and a shark tooth! Also inoceramid clam fragments, encrusted with oysters (apparently a common feature of the bottom of the Western Interior Seaway). No mosasaurs, though... Back to the road, and into Hays, Kansas, where Ron put me up in his guest room. We had dinner and a few beers at the Lb. Brewing Company, and thought about recording a PodClast, but then it slipped our minds. We discussed field trips, tenure, publications, and related topics. A good time! Thanks again to Ron for being such an excellent host.

The next two days (Tuesday and Wednesday) were essentially just driving. On Tuesday, I made it to Indianapolis, Indiana, and spent the night in a hotel there. On Wednesday, I turned north, and drove up into Michigan, and crossed into Ontario at Port Huron / Sarnia. Why go to Canada on my way from Montana to DC? Well, I'm teaching my Snowball Earth class this week at NOVA, and some of the rock samples I needed were stuck at Brock University in St. Catherines, Ontario. Usually they get shipped to educators who want to use them, but because of alleged border complications, I had to go get them myself; a five hundred mile detour! Fortunately, I have good friends who leave in Waterloo, Ontario, so I went and stayed with them. Mike and Natalie Leuty have been friends since 1996, and we had a good evening catching up. They have a sweet house in a suburb full of professorial types who teach at one of the several universities in town.

On Thursday morning, Mike and I had coffee on his front porch while his kids played in the yard, and then I packed up my kit and got rolling. I made it to Brock by 11am, and got the Snowball Suite. Because it's in a giant black case that looks suspiciously like a rifle case, I packed it under a pile of other gear in my car. At any rate, I crossed back into the United States without any static from customs officials, and rolled through Buffalo, New York (twice in one year!) I made my destination for the night Ithaca, New York, where I have a friend who's going to grad school at Cornell. I've never been to Ithaca, but I hear that it's "gorges" from many people. So I called my friend, Kathryn Werntz, and she was indeed around and accepting visitors, so I drove through the finger lakes region (five subparallel glacial troughs now filled with water), and found my way to her bungalow. Kathryn and I took a walk through Cornell's campus (two amazing gorges cutting through it), had some Indian food, and went to get dessert at Purity Ice Cream.

In the morning (Friday), I got up and we went to Gimme! Coffee for some caffeine. Thus fortified, I hit the road for my final day of driving. East to I-81, then south through Pennsylvania. At Harrisburg, I turned onto I-83, which took me to Baltimore, and from there it was a familiar zoom down the B-W Parkway into northeast DC. The dome of the Captiol was visible to my left, and then the comfortable sights of Florida Avenue and U Street. Up the hill, and a left on Harvard Street, and I was back in Adams-Morgan. Home! Finally!

Labels: appalachians, canada, chalk, colorado, field trips, glacial landforms, kansas, montana, national parks, new york, snowball earth, structure, travel, wyoming

And here's the view hiking back down the canyon to the car:

It's a classic U-shaped valley, the signature of alpine glacial topography. Here's the Google Maps "terrain" view of this valley:

View Larger Map

Labels: glacial landforms, montana, volcano

Last summer, when I was out in Montana, I had a break of five days or so between classes, and so I headed out to Missoula to visit with my friend Noah. He and I went backpacking up to the Walton Lakes area, across the border in Idaho. We're walking across exposures of the Idaho Batholith here (Mesozoic felsic intrusive rocks, kind of like the Sierra Nevada Batholith in California). But probably the more striking thing is the topography, which has been beautifully sculpted by glaciation:

With a tarn in the background, here's Noah and his dog "Sanoma" (not the way I would spell it, but hey, it's not my dog...) walking along the ridge:


Sanoma with her doggy backpack:


Snowpack remains, even in July:


A nice view along the "knife edge" of an arete, the crisp slice of bedrock remaining between two glacially-carved valleys:


Noah and Sanoma standing on the arete:


Classic glacial topography: Note the arete (far right), cirque headwall (in shadow), tarn (lake in center), and end-moraine (light band at left).


We hiked down to that tarn and went swimming in it. Then we camped on the moraine that night, amid a great many mosquitoes. But the sunset was nice:

Labels: glacial landforms, granite

We've had a cold week in the mid-Atlantic this week, and increasingly my thoughts turn to warmer conditions and the summer. Last year, this year, and next year, I'm scheduling time in Bozeman, Montana, to take classes at Montana State University. I'm working on a second master's degree in science education. It's a pretty cool program which mixes educational practice and "action research" with science elective courses, including plenty of geology offerings.

Today in the blog, I thought I would begin the process of share some images from my time out west last summer. I'll start with the Bridger Range, north of Bozeman. Here's a meadow where we parked the vans before hiking up into the hills on Dave Lageson's excellent Alpine Field Studies seminar:


Once we had huffed and puffed up about tree line, we started to see some pretty cool geology. Here for instance, you can see tilted, folded, faulted Mississippian-aged strata that have been carved into by a glacier. A few minutes after this photo was taken, the class walked straight down into this cirque and climbed up the other side: there's some serious gravity-fighting going on with a route like that. We had lunch on the other side at the top of that orange-colored chute in the upper left:


In the photo below, my hands bracket a tilted zone of paleo-karst in the Mississippian-aged Madison Limestone. With massive limestone above and below, this orangey zone speaks of a time when the limestone deposits of this area were exposed at the surface. Caves and sinkholes developed, as did an iron-rich paleo-soil. It probably looked a lot like modern-day Florida, without the strip malls and retirees. Later, the sea returned and deposited more limestone on top. The paleo-karst is obvious because it contains big blocks of limestone from cave-roof collapse, and is stained by hematite and limonite:


Fellow DC resident and geology educator Nez Nesbitt follows Dave Lageson (the instructor) south along the crest of the range. The drop to either side was substantial, including the headwall of a cirque to the left (east). The loose scree we were walking over added an additional challenge:

In all that scree on the slope we're walking over, there were some cool fossils, including this awesome crinoid calyx ("head" region) - front and back views:


Atop a peak, we paused for a break, and Dave unfurled his Tibetan prayer flags to flap in the wind. I was struck by how a simple little string of cloth imparted a really cool aesthetic to the mountain-top:


This is the trail leading down Sacagawea Cirque. There's some substantial switchbacking going on here:


Here's me atop the highest peak in the Bridger Range, Sacagawea Peak. The views are pretty good from up there:


The class spent the next day mapping glacial landforms in Sacagawea Cirque: it was fun, but I didn't take as many pictures then. When the mapping was over, I prowled through the lateral moraines for fossiliferous chunks of limestone, and found some awesome rugose corals and other treasures. These samples now reside in the NOVA Historical Geology teaching collection.

Labels: fossils, geology, glacial landforms, montana, msse, structure

Geological Travels in Northern Ireland, Part VII:

Ground moraine being used (quite appropriately) as a golf course, east of Port Rush.

An old quarry south of the road between Bushmills and Port Rush. This is easily accessible from the parking area for White Rocks, a popular surfing beach. (Yes, they surf in December in Northern Ireland!)

Well-exposed here is the unconformity between the Cretaceous-aged "Chalk" (the Ulster White Limestone) and the overlying "Lower" Basalts (Paleogene in age).

The ancient topography is revealed in the undulations of the unconformity surface: prominently featured here is an ancient valley that was topped off with basaltic lava during the eruption. Valley depth in this photo is about 80 feet.

The limestone ("Chalk") here was quarried for lime. Lime is the binding agent in cement and mortar, and it is produced from the burning of limestone. Disused kilns from the burning process were still situated in the quarry. The area was lousy with flint nodules, like the one here. I collected a beautiful one that looked like a cross between a sausage and a powdered donut, but security confiscated it from my carry-on luggage on my flight back home.

Labels: antrim coast, basalt, chalk, concretions, flint, geology, glacial landforms, northern ireland, unconformities