Yesterday we looked at some other aspects of Argentina's Parque Nacional Los Glaciares (and the nearby town of El Calafate). Today, some pictures of ice.

Let's orient ourselves first, courtesy of some satellite imagery via Google Maps:

You can see the bright blue of Lago Argentino, including its southern arm, the Brazo Rico. Separating the Brazo Rico from the main part of the lake is the Magallanes Peninsula. And poking out from the white mass at left (the South Patagonian Ice Field) is a nice big valley glacier, the Perito Moreno Glacier. Notice how it pokes right into the Magallanes Peninsula, like a pin approaching a balloon. Occasionally, it surges forward and smooches the opposite shore, cutting the Brazo Rico off from the rest of the lake. When this happens, some spectacular collapses can occur.

The Perito Moreno Glacier is remarkably stable, due in part to its large catchment area and relatively narrow zone of ablation. This means that a bunch of park infrastructure has developed on the Magallanes Peninsula: viewing platforms and docks. The glacier moves forward at the same rate it loses ice through calving/melting: very consistent. We started off with the boat trip up to the glacier's terminus. Here's a view of the boat from above:


...And a view of the glacier's face from the boat:




Ice meets bedrock (plants watch warily):


Looking north from the viewing platform:












A little panorama (two shots spliced together):


So, at this point, I hope I have established that Perito Moreno Glacier is very accessible and very photogenic. It is also a lovely shade of blue. Thank you very much.

Labels: argentina, glaciation, patagonia, south america, travel

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

Good timing! National Geographic's new issue (which we got yesterday) discusses many of the same regions of Patagonia that I've been describing here over the past two weeks. You won't find any graded beds in their pages, but they do have some spectactular imagery of the Grey Glacier (via NASA) and the Chilean coast. The NatGeo website has a nice slideshow of photos by Maria Stenzel. The story's lead image is... Torres del Paine.

Labels: chile, glaciation, national parks, patagonia, south america

On Boxing Day morn (Dec. 26), we woke at Refugio Grey, and took our camp stove outside. Just for a lark, we walked over to the shore where an iceberg had beached itself, and popped off a chunk to melt and make coffee:

You haven't really had coffee until you've had coffee made with water that's been locked out of the hydrologic cycle for 14,000 years!

With warm coffee and a granola bar apiece, we walked over the small peninsula where Regugio Grey is located to the bay on the other side. There, a flotilla of icebergs had rafted up against the peninsula. We decided to spend a little bit checking them out, before heading out on the day's (short) hike to the next refugio. We had it all to ourselves:


The icebergs varied tremendously in size, shape, color, and texture.


So, presented with a wealth of icebergs like this, what would you do? If you answered "put one on my head!" then apparently you think the same way that we do:


Silliness expended and coffee consumed, we grabbed our packs and hit the trail again. Today's destination was the Paine Grande Lodge. It wasn't an especially long hike, and it was essentially parallel to Lago Grey for most of the distance. Here's some more icebergs, further down the lake:


One geological site that really caught my attention was this sweet outcrop showing gorgeously folded turbidite layers. To give a sense of scale, each of those green bushes is about 1 meter in diameter:


Here's (white arrow) the Paine Grande Lodge, on the shore of a new lake (you can tell by the color), Lago Pehoe.


Closer in shows the detail of this nice, modern facility:



It was our second night indoors, and while it was a bummer that we had to share our room (6 bunks) with 4 other people, one 'up' side was that the Paine Grande took credit cards, which mean that the pisco sours were on Callan and Lily!

This is the lounge, with a nice woodstove and great views of the landscape for birdwatching or just sitting back and feeling satisfied. We spend a while hanging out here, particularly as a few rain squalls moved through.

The usual routine followed: dinner, bed, dawn, coffee, hiking... on to Day 6!

Labels: chile, glaciation, ice, patagonia, south america, structure, travel

Christmas day in Torres del Paine National Park: We packed up our gear at Paso Campground, and hit the trail in the rain. It rained on us for about an hour as we walked south, parallel to the downstream flow of the Grey Glacier, a huge gleaming presence to our right. Occasionally, the trail exited the forest as we had to cross deep ravines, like this one:


Snowmelt coming off the Paine Massif carved these ravines, and the park service had placed ladders in a few key locations, like this one:


Some people didn't like the ladders very much:


Once we got far enough along, we could see the terminus of the Grey Glacier:

Umm, wow.

Slightly different photo composition, with a tree in the foreground:


Nothing but terminus:


Looking south-ish, down the axis of Lago Grey:

Our destination for the evening was Refugio Grey, located on the far side of that first little hook-shaped peninsula.

Iceberg in Lago Grey:


Refugio Grey:

This was our first night spent under a roof on this trip. After three nights in a tent (me with a flat Therm-a-rest), it was quite luxurious to indulge in hot showers and a mattress! We also had a superb Christmas dinner behind those plate-glass windows, eating pork loin and drinking Gato and watching icebergs float by. It was pretty freaking cool.

That afternoon, we went for a walk down the beach, checking out the rocks. There were nice sedimentary structures and nice tectonic structures. Here's some trace fossils seen on one of the bedding planes of the turbidite strata:

I saw a fair amount of bioturbation in the turbidites, but this was without question the best exposure I saw.

Here's a tight little anticline:


Callan takes a nap in a little synclinal bed:


Flame structures with palimpsest glacial striations:


And another set, a few feet over to the right (same bed):

There appear to be some burrows here, too (the little circles of sandstone in the mudstone below the main sandstone contact).

We slept well that night. I was especially pleased by the fact that it rained for half the night (since I was sleeping indoors).

Labels: chile, fossils, glaciation, ice, patagonia, primary structures, south america, structure, travel

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

After our explorations of the Los Perros Glacier, its moraine, and the bedrock it has scraped so deliciously clean, we headed on up the trail, towards the highest point on Torres del Paine's Grand Circuit: Paso John Gardner. Here's a look back at the valley we've been hiking up from Refugio Dickson... Note the Los Perros moraine and the edge of the lake:


First graded bed of the day. I photographed this one for the lovely scours into the underlying muddy (dark) layer:


Another turbidite clast. Is that a clastic dike on the left?


I thought this was really cool, too. It's a vein: a fracture filled in with a mineral deposit. I really like here how you can see little shreddy flakes of the mudrock (dark) peeling back and flexing in the fracture's void space (prior to being locked in place by mineral deposits):

I interpret this to indicate that the fracture opened in a transtensional fashion, with the top to the right.

A ravine revealed this blind thrust:


Can't see it? Here's an annotated version. The thrust fault below morphs into a fold further up:


A sand-dominated series of graded beds:


Annotated below. Some of the turbidites I saw were a meter thick!

...and what's up with those rotty-appearing rusty spheres? (like the one left of my boot) I saw them several places... hematite concretions? (???)

Brace yourself. Here is possibly the most spectacular boulder I've ever seen:


Annotated version below. This boulder shows a series of graded beds (sand = light colored; mud = dark colored). The direction of gradation shows us that the boulder is upside-down relative to original depositional orientation. A couple of small flame structures reinforce this interpretation. It has been gently folded into a broad anticline (remember, it's upside-down!) and there appear to be some small "parasitic folds" superimposed on the broader fold (at boulder-bottom; depositional-top). Additionally, the turbidites are cross-cut by a small fault which has offset the layers. If I could choose just one boulder to be airlifted from Patagonia to the front of the Science Building at NOVA, this would be the one I would choose.


We keep hiking. We cross several snowfields and other bouldery alluvial aprons, interspersed with fingers of forest reaching up towards the hills. Looking up at the peaks, we can see turbidite layers intensely folded. Check out the straight-limbed anticline (left) and syncline (center) on this mountainside:


Looking up ahead -- there at the left center (between the two peaks) is John Gardner Pass:


We cross through a few more stretches of forest. This one really struck me: "Creep much?"

Besides the freeze-thaw soil-shoving action of creep, I think another factor for the J-shaped (or even L-shaped) tree trunks in this forest is the thick blanket of snow they get each winter: this tamps down the whole forest in a downhill direction.

Look! On the left! Another glacier!


...Shift the perspective a bit, and something else pops out. Once the hammy glacier is off-screen, you can see the wallflower in the background: A mountain composed of pink granite rather than black turbidites.


We keep climbing. Higher up, another opportunity for gazing down the valley we have climbed. The Los Perros Glacier moraine and lake are readily distinguishable even from this distance:


Up in the snow, we trudge higher and higher, and eventually reach the Pass. But for that, and for what we saw on the other side... I'm going to make you wait for Part III.

Labels: chile, glaciation, mass wasting, patagonia, primary structures, south america, structure, 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

Rested up from Day 1 in Torres del Paine, we were pleased to see that day 2 dawned bright and sunny.

Lily takes a morning break to shed layers:

The weather in Patagonia was really variable, as was the trail. This meant that all day long, we were stopping to put on layers or take off layers as we got cold or hot. It was kind of a pain. Whine whine whine.

All day, clouds scudded along, but we didn't get any rain until late in the day. The main part of the Paine massif was coming into view. Here's a shot from noon-ish:


Here's a shocker: ...We saw more rocks!

Here's another graded bed:


And a little plumose structure, showing a nice twisty hackle fringe:


When I first saw this outcrop, my brain's pattern-recognition center peeped: "CRINOID STEMS!"

...But upon closer examination, they lacked pentameral symmetry, and were some were kind of lumpy. And considering the main rock here is Cretaceous-aged, crinoids could be present, but they aren't as likely a candidate for fossilization as they would have been if these rocks were Paleozoic. So I think these were concretions of some kind. Chert? I shared this image with Patagonia geology expert Brian Romans, and he pointed out something I hadn't noticed in this image: the flame structure in the lower left. That indicates this boulder is upside-down, relative to its original depositional position.

Here's another concentrically-zoned jobbie, which I interpret as a concretion. Overall, this thing was like a pig-in-a-blanket, but on steroids:

I think it's a flint nodule. Brian hasn't seen any crinoids or any concretions in these rocks, so I'm at a loss to offer further explanation.

I was flummoxed by this one, too:

This time, the pattern-recognition center wanted it to be a trilobite, but that's impossible (or, strictly speaking, not impossible but history-re-writing-able) in these aged rocks. Brian tells me it's almost certainly an inoceramid bivalve. That works for me.
(...Or could it be... pseudosegments???)

We walked on, through fields of little white flowers:


Angling towards the main massif, more gnarly peaks came into view...


One thing you can see well in this shot is the contrast between the color of the darker Cretaceous-aged sedimentary host rocks (turbidites) and the light-pink-colored granite which intruded them around 12 million years ago (Miocene).


A bit further on, we could get a decent look at the intrusive relations (through binoculars):

(In this annotated photo, "T" is for "turbidite," "Gr" is for "granite.")

We dropped down off a moraine towards Refugio Dickson, where we made tea, rested a bit, and pushed on again...


At the head of Lago Dickson was an impressive looking glacier, dropped down out of the South Patagonian Ice Field and into the lake:


It was around 1pm when we got to Dickson. We were tired, but the day was only half over. We decided to push on, and essentially do two days' hiking in one. Next stop: Refugio Los Perros!

We hiked on through PRIME Magellanic woodpecker habitat, and it just KILLS me that I didn't see one there, though I did see a few other new birds. Then the rain started, and we started to get tired. But we were committed at this point... We pushed on, and on, and on, and on, climbing up through a forested valley, until finally we popped out on fresh glacial moraine, and saw this:

That's the Los Perros Glacier! A short distance further up the valley was the campground. At this point, the rain had morphed into snow, blasting us in the face as we slogged along, really looking forward to dinner and sleep. Maybe not in that precise order. Eventually, we got there.

Fortunately, the clouds parted for literally 5 minutes, and we were able to have our portrait taken by a doctor from Santiago, who was hiking there for Christmas with his family. They were literally the only Chileans we met who were in the park as tourists (i.e., not park employees or concessionaires) our entire trip. I think we look happy to be in such a special place, don't you?


Next up: Day 3, when we cross John Gardner Pass and see the Grey Glacier for the first time!

Labels: chile, cretaceous, fossils, glaciation, granite, miocene, mountains, patagonia, primary structures, sediment, structure, travel

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

Remember how I was lamenting the carbon footprint of my globetrotting?

Here's a nice summary of that issue in an image:

Smoke from the engines of the M.V. Evangelistas drifts across the terminus of the largest valley glacier in South America.

Labels: chile, climate change, CO2, environmental, glaciation, global warming, patagonia, south america, travel

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

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

Educators! If you're looking for an excellent image of a piedmont glacier to show your students, consider this one. Wowzers.

Labels: glaciation

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

If you haven't seen this yet, please watch it. Nice work, Mr. Balog!

Labels: art, climate change, glaciation, global warming, ice, meetings

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

Last night, I took a group of Honors students to the United States Geological Survey's National Center in Reston, Virginia, for a public lecture by Bruce Molnia about Alaska's disappearing glaciers. The talk was all well & good, but a nice little surprise came afterwards, when Jared noticed a display in the lobby of the Dallas Peck Memorial Auditorium:

That's the classic "ancient Chinese seismograph" featured in so many introductory geology textbooks as the lead-in to their chapters on earthquakes and seismology. Pretty cool to see it in the flesh brass.

The way it works is that each of the little dragon heads projecting off the urn had a little brass ball in its mouth. If it got shaken by an earthquake, that little brass ball would pop out and into the waiting mouth of the little brass frog down below. The frogs aligned with the wave propogation direction would be the ones to be "fed." This implication of the temblor's source direction would allow authorities to direct scouts and relief operations to the appropriate corner of the dynasty.

Neat!

Labels: alaska, earthquakes, gear, glaciation, nova, rept, teaching

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

Paul Hoffman is speaking next Wednesday (April 22) at the Geological Society of Washington; I've just recieved word that his topic has changed from Snowball Earth to "The Pleistocene glacial controversy and the discovery of climate warming and crustal dynamics." I'm curious to see what Hoffman has to say about the 160-year old controversy as to whether there had been recent "Ice Ages," and how that relates to his currently-controversial ideas about the Snowball. Whatever he says, it's likely to be thought provoking.

Labels: geologists, glaciation, gsw, ice, pleistocene, science and society, snowball earth

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

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

The International Year of Planet Earth may have declared a list of "the Earth's ten most spectacular places." At least that's what they're saying at the Discovery Channel's new Discovery Earth site, where they have a rundown of all ten (with photos). (No mention of it at the IYPE site, though: It may be that the Discovery Channel is just highlighting ten of the many, many U.N. World Heritage sites... their language is unclear as to who decided on these particular ten.)

Regardless, the photos will whet your appetite. With my visits in bold, they are:

• The Giant's Causeway, Northern Ireland (posts on NOVA Geoblog)
• Wadi Al-Hitan (Valley of the Whales), Egypt (Eric's been posting on this recently)
• Lake Baikal, Siberia (deep, big)
• Komodo National Park, Indonesia (big monitor lizards; my friend Kenny has been)
• Grand Canyon, Arizona, USA (posts on NOVA Geoblog)
• Ilulissat Icefjord, Denmark (glacial beauty)
• Wulingyuan, China (quartzite pillars and indigenous fauna)
• Surtsey, Iceland (46 years old this year)
• Central Amazon, Brazil
• Great Barrier Reef, Australia

Labels: antrim coast, asia, australia, china, fossils, giants causeway, glaciation, grand canyon, ice, reefs, south america, travel, water resources

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

Would you like a little geoblogosphere with your coffee this morning?

There's some great stuff out there today...

Andrew Alden (Geology.About.com) showcases the Fransiscan melange on a trip to Shell Beach.

Watch Perito Moreno glacier do some AWESOME calving at En Morrenas (Spanish-language geoblog). Watch the whole thing for perspective (3 minutes), but the really spectacular collapse occurs at ~2 minutes into the video. Watch the splash and watch the huge chunks of ice go zinging off into the surrounding air. Wild!

Dave Petley (Dave's Landslide Blog) reviews the dangers of a collapse of a volcanic flank in the Canary Islands, and what it means for Atlantic Ocean tsunami risk.

And for the geobloggers in the house, Chris proposes getting together in January at a science blogging conference in North Carolina. I think this could be cool. I just signed up.

Time for another cup of coffee... Good morning!

Labels: blogs, california, geology, glaciation, landslide, meetings, north carolina, south america