The Grand Tetons: Overview   Leave a comment

In Grand Teton National Park, Wyoming, old homesteads cluster together in an area known as Mormon Row.

I’ve been here a couple times over the past two years, once late August last year, and now in early October.  One of these years I may visit during the mid- to late-September period of peak Autumn colors.  But then again, given it’s popularity for photography workshops and groups during that time, maybe not.  Even now there are plenty of photographers here. I’m really not the type to fight other photographers for tripod space.

All that aside, it is really a nice National Park. I like the fact that it is less crowded and has less uptight staff than Yellowstone just to the north.  Who amongst us mountain lovers cannot love the Grand Tetons.  They are spectacular mountains, named by French trappers for the “big tits” they might have thought often about while paddling endless miles in search of beaver.  But as you can see from the pictures, if there are breasts like this on a woman somewhere, I would like to see them (or maybe not!).  The mountains, especially the Grand Teton, which at 13,770 feet (4200 meters) is the highest in the range, are by no means smooth.  In fact, they rise in jagged splendor from the Great Plains to the east.

A view of the high alpine country, Grand Tetons, Wyoming includes a beautiful tarn, erratics and an arrete.

Geological Tangent (feel free to skip if you’re not especially interested in how mountains are formed)

The Grand Teton is obviously the highest in the range viewed from most any angle, here from near park headquarters at Moose, Wyoming.

The Grand Tetons’ steepest side is to the east, on the Wyoming side. This sheer mountain front lies along a steep-angled fault in the earth’s crust called by geologists a normal fault.  The mountains rise (or remain static) while the basin drops along a steep (70 degrees or so) fault zone.  Jackson Hole is the lowest point of this down-dropped basin.  “So what” you might say.  How does this tie into the formation of the Rocky Mountains?  Well, this is a big deal.  It’s the main geological process that has made continents out of what was originally not much more than volcanic islands sticking out of a much-larger-than-now ocean.

In the case of the Rockies, back in the Dinosaurs’ prime time (the late Cretaceous) some 55-90 million years ago, the enormous Pacific tectonic plate (actually geologists call it the Farallon Plate to distinguish it from the modern Pacific Plate) got serious about pushing east against the North American Plate.  It had been doing so for a long time before this, but during the time the Rockies were formed it dove beneath the continent (as oceanic plates will do) at a much shallower angle.  This forced mountain building much farther inland than usual.  The tectonic collision resulted in buckling, folding, mashing and munching in rocks buried deep within the earth.  This “Laramide Orogeny” initially formed a large, high plateau, like modern Tibet.

Much of the massive compression during collisions between ocean basins and continents happens because numerous islands (which don’t dive down beneath the continent as well-behaved oceanic crust typically does) are slammed up against the continent.  It’s a process called accretion, and is responsible for  much of western California and the coastal ranges of the Pacific Northwest and Canada.  Anyway, as hinted at above, the orogeny did not push up the high mountains of the Rockes right away.  That’s what many people believe when they learn about this stuff.  Instead, the action took place deep below ground and very slowly (geological things are mostly very slow).

One thing that happened, other than the aforementioned folding and mashing, was melting.  Rocks on the continent melt at a relatively low temperature compared to those under the oceans.  Plus, since they’re made of a more diverse assortment of rocks, which all melt at different temps., the melting is really partial.  This means a lot of smallish magma chambers separated by solid (but hot!) rock.  I know, a lot of detail.

But here’s the kicker:  melted rock is lighter than solid rock.  And what’s more, partial melting then cooling of continental rocks result in granite and its relatives.  These are some of the lightest rocks around.  You might not be able to tell, with a piece of (oceanic) basalt in your left hand, a piece of granite in your right; but if you wait a half-million years, your right hand will start to rise while your left sinks.

This is what happens with mountain ranges like the Rockies (and Alps, Caucuses, etc.).  After much of the damage has been done by the compression and heating deep within the Earth, the crust adjusts.  The lighter rock, some still molten, rises and pushes up the land.  One other thing though.  The Earth’s crust along a mountain range like the Rockies thickens (’cause of the buckling and melting both).  But there’s a lot more rock added beneath the mountains than what is pushed up.  In other words, the root of the mountains, deep beneath our feet, is much more impressive than the height of the mountains.  This fact leads to a flexing upward of the entire crust along the length of the mountain range, as the crust adjusts to the added mass below.  This so-called isostatic adjustment really is the main cause for the creation of high country.

Anyway, once the mountain range is well on its way to being nice and high, two things happen.  The main thing, of course, is erosion.  (This is part of the reason for the root being much greater than the height.)  Water and (much later in the case of the Rockies) glacial ice, begins early and never, ever gives up its assault on the high ground.  Erosion, as you might have heard, always wins in the end.  But in the meantime, as long as the tectonic collision continues, the (lighter) mountains continue to rise, and the age-old battle with erosion is waged.

Mount Moran stands at the north end of the high Tetons in Wyoming.

Now we are finally back to the Tetons.  Well, the story is a bit complex, but the main thing you need to realize is that once all this land is lifted up, you often get stretching along the far (east) side of the mountain range from the big oceanic plate that’s causing all this havoc.  This area behind the mountains has long been called by geologiasts (even before the theory of plate tectonics) the “foreland belt”.  In the case of western North America, there was more than this normal extension along the foreland.  After all those ages of compression along the edge of western North America, which lifted the West we enjoy today from beneath the waves, the situation reversed in a big way.

Well into the Tertiary (the time of the rise of mammals), a pulling apart began, forming the Basin and Range.  We went from compression to extension because the Farallon Plate disappeared beneath North America and the modern Pacific Plate started to slide past the edge of North America along the San Andreas Fault.  Like people, continents, at least along their active margins, are rarely standing still.  They’re either getting munched or being pulled apart, albeit much more slowly than we our changes.  North America’s western edge has now entered a period where things could start getting pulled off it instead of added.  Eastern Africa is a bit further along this path, and a sea will eventually invade the Great Rift Valley there.  The same might occur here too, starting in SE California and southern Nevada and extending northward.

So I know I’m taking a while to get back to the Tetons.  The Basin & Range extension that continues today results in steep-angled normal faults, which in brittle rocks close to the surface is the way any rock will respond to being stretched.  The normal faults along the eastern back-side of the Rockies are the furthest east of these faults; nost occur in Nevada and bordering states, where the crust is much thinner.  But in the thicker crust of the rockes, these faults are responsible for some of the most spectacular mountain scenery of western North America.  The Grand Tetons are just one example.  It really is the end-game of mountain building here, where the thickened crust under the western Plains has fallen dramatically down while the Tetons have risen along the Teton Fault.  There is only so much rising and thickening to be accomplished before things start to break apart.

The battle between the rise of these mountains along the Teton Fault on one hand, and erosion on the other, creates the rugged, fantastic mountain landscape that climbers and photographers, that all of us really, admire.  But count yourself lucky that you are alive to enjoy it right now.  After all, it’s a temporary situation.  Remember, erosion always wins in the end.

In the Gros Ventre Mountains east of Jackson Hole, Wyoming, an earthquake in the 1950s created a beautiful lake. The well-named Red Hills are in the background.

Back to the Trip

I know that was a long-winded explanation, but if you sorta got it, you get the whole thing about mountain building throughout the world.  Well, besides the building of strictly volcanic mountain ranges, but a lot of the same concepts apply there too.

I spent a half a week here in the Tetons this time, not doing as much hiking as last year (see image of the tarn 2nd from the top, taken at the top of Paintbrush Canyon).  Also last year, I made it up the rough dirt road east of the Tetons, where there’s a gorgeous, quiet lake (image above).  But I did manage to wake for each sunrise this time, even though they were mostly blah in terms of color.  The leaves on the aspens and cottonwoods were browning rapidly, and the whole landscape looked dry and thirsty.  Fires continuing to burn in the region added some haze and smoke to the air.  In short, light for photography was not ideal.

But along came the evening of the 8th of October.  Clouds built through the afternoon over the Tetons, and I took a run along the excellent bike trail that stretches 20 miles from the town of Jackson and Jenny Lake in the Park (no I didn’t run 20 miles!).  After the sun set behind the mountains, as I expected might happen, the clouds lit up.   All of a sudden we had a fiery sunset!  I was not at one of the classic locations for landscape photography in this area, but near the park’s headquarters in Moose.

Ansel Adams made places like the Snake River Overlook and Oxbow Bend famous, and to get dawn and dusk shots from these spots you would need to fight for your tripod space.  I’m not into it.  So I just walked around the Snake River bridge near Moose, finding a spot where I could get a nice panorama of the Tetons.  I was happy.  One more post on the Tetons is to come, focusing on the wildlife.

The Grand Tetons surprise me with a fiery sunset on my last night in the park.

Please don't be shy; your words are what makes my day!

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

<span>%d</span> bloggers like this: