If These Cliffs Could Talk: Tis-sa-ack and Tu-tok-a-nu-la (A Geologic Love Story Redux)

I've been to Yosemite Valley twice in the last month, including a day when the Merced River was still at flood stage. I was reflecting on the many journeys I've made there with my students and with Mrs. Geotripper, and what a stunning place it truly is. I was thinking of a new angle to present some pictures of the latest trips, but then my good friend @phaneritic on Twitter asked a question about quotes concerning the valley that don't involve the writings of John Muir (as wonderful and poetic as his words were). I realized I had written about some of the legends of Yosemite a few years ago, and decided it was time to bring some of them back, in case they were missed before.

These stories also have relevance to the moment because of the decidedly stupid legal war over trademarks being waged between the National Park Service and the recently departed Delaware North concessionaire. One current sign of the ongoing legal battle is the new name for the Ahwahnee Hotel ("Majestic Yosemite") and Curry Village ("Half Dome Village"). Half Dome is a very plain name for such a stupendous rock, and I am thinking the park service missed an opportunity. Tis-sa-ack Village might have been a mouthful to pronounce, but it gives the rock a history and an air of mystery.

And so here it is, the story of Tis-sa-ack and Tu-tok-a-nu-la, a geologic love story, first published in November 14, 2014:

Tis-sa-ack (Half Dome) from near Yosemite Falls

A love story...

Unnumbered snows have come and gone since The Great Spirit led a band of his favorite children into the mountains, and bade them rest in this beautiful Valley of Ah-wah-nee. They were weary and footsore, and were glad to rest after their long journey. Here they found food in abundance. The streams held swarms of fish, meadows were knee-deep in sweet clover, great herds of deer roamed the forests in the Valley, and on the high mountains, oak trees were bending under the weight of their acorns, grass seeds and wild fruits and berries grew in bountiful profusion. Here they stayed and built their villages. They were happy, and multiplied, and prospered and became a great nation.

North Dome, Washington Column, and Half Dome in the clouds

How many stories begin in paradise?

I find the myths of different cultures to be fascinating. They provided their people with an explanation of the unexplainable, a comforting story that suggests there is order in the apparent chaos of the universe. In the perspective of geology, we can sometimes see the whispers of eyewitnesses to significant geologic events: the eruption of Mt. Mazama, for instance, which resulted in the formation of Crater Lake, is described in Native American oral histories. In this post we see one of the legends of Yosemite Valley, with all the embellishments and cultural biases of a 1922 narrative. Still, it's a good story

To their chief came a little son to gladden his heart. They wanted this son to become a great chief, capable of the leadership of a great people. He was made to sleep in the robes of the skins of the beaver and the coyote, that he might grow wise in building and keen of scent. As he grew older he was fed the meat of the fish, that he might become a strong swimmer, and the flesh of the deer, that he might be light and swift of foot. He was made to eat the eggs of the great crane, that he might be keen of sight. He was wrapped in the skin of the monarch of the forest, the grizzly bear, that he might grow up fearless and strong in combat. 

So many stories come with the hero, and the most interesting stories have heroes with flaws...they had everything. But then things happen. The world and the people who live in it are not perfect. And frankly, life would not be interesting.

And, when he grew to manhood, he was a great chief and beloved of all the people. His people prepared for him a lofty throne on the crown of the great rock which guards The Gateway of the Valley, and he was called Tu-tok-a-nu-la, after the great cranes that lived in the meadow near the top. The people of Ah-wah-nee were happy, for Tu-tok-a-nu-la was a wise and a good ruler. From his high rocky throne he kept watch over the Valley and the people whom he loved. He called on The Great Spirit who sent timely rains, so that the acorns grew in abundance, the hunters returned from the forests with game, and the fishermen from the streams with fish. There was peace and plenty throughout the Valley of Ah-wah-nee, and when Tu-tok-a-nu-la held speech with his people from his high throne his voice was deep and strong like the deep sound of the waterfall.

Tis-sa-ack from Sentinel Bridge

But paradise can't last forever. Trouble was coming, or more to the point, the trouble lay hidden in the heart of the hero, and it was about to be made manifest. There were no doubt all kinds of communications between the many Native American bands in California, and the trading of knowledge and technology. I'm sure this led to problems at times as well.

One day as Tu-tok-a-nu-la sat gazing into the glowing colors of the west, he saw approaching his valley a strange people, led by a maiden of wondrous loveliness. He called to them and the maiden answered him, saying, "It is I, Tis-sa-ack. We have come from the land of my people in the far south to visit with you. We have heard of the great and good chief, Tu-tok-a-nu-la, of his great people and his wonderful valley. We bring presents of baskets and beads and skins. After we have rested we will return to my people in the far south." Tu-tok-a-nu-la welcomed the fair visitor from the land to the
south and had prepared for her and her people a home on the summit of the great dome at the eastern end of the Valley. There she stayed and taught the women of Ah-wah-nee the arts of her people. Tu-tok-a-nu-la visited her often in her mountain home. He was charmed by her wonderful beauty and sweetness, and begged her to stay and become his wife, but she denied him, saying: "No, I must soon return with my people to their home in the far south." And, when Tu-tok-a-nu-la grew importunate in his wooing, she left her home in the night and was never seen again.
 

To-ko-ya (North Dome), Nangas (Washington Column) and Tis-sa-ack (Half Dome) from Glacier Point. The Ahwiyah Point rockfall scar is visible just right of center below Half Dome.

The perfect women, the Helen of Troy, the Eve. Of course, perfection is a tricky concept, subject to many biases and assumptions. It doesn't much take into account the actual relationship between those involved. As Mr. Spock mentioned in a famous episode of Star Trek: "After a time, you may find that having is not so pleasing a thing after all as wanting". Bad things are about to happen.

I admit, I've never heard the word importunate before. 

When the great chief knew that she was gone, a terrible loneliness and sorrow came to him, and he wandered away through the forests in search of her, forgetting his people in Ah-wah-nee. So strong was his love for her, and so deep his sorrow, that he forgot to call upon The Great Spirit to send the timely rains. So great was his neglect that the streams grew smaller and smaller and finally became dry. The crops failed. The hunters came back from the forests without meat, and the fishermen returned from the streams empty-handed. The leaves and the green acorns fell from the trees, and the bright flowers and green grasses became dry and brown.

From Washburn Point it is obvious that Half Dome isn't just a boring name, it is a mathematically wrong name. Three-Quarter Dome, maybe. I would just go with Tis-sa-ack

This is where the geologist in me starts paying attention. California has droughts, and there is evidence of mega-droughts that lasted more than a century. Check out this post for some of the striking evidence. These droughts both occurred within the last 2,000 years, recently enough to be remembered in the oral histories of a people.

And then things get interesting in a hurry...

The Great Spirit became very angry with Tu-tok-a-nu-la. The earth trembled with his wrath so that the rocks fell down into the Valley from the surrounding cliffs. The sky and the mountains belched forth smoke and flame. The great dome that had been the home of Tis-sa-ack, was rent asunder and half of it fell into the Valley. The melting snows from the high mountains came down into the Valley in a flood and drowned hundreds of the people. But the wrath of The Great Spirit was quickly spent, and the heavens again grew quiet. The floods receded, the sun shone, and once more peace and calm reigned over Ah-wah-nee. The life-giving moisture from the renewed streams crept into the parched soil. The oak trees put on new leaves and acorns. The grasses again became fresh and green, the flowers lifted their drooping heads and took on their old gay colors. The fish came back to the streams, and the game to the forests.

Wow.

"The earth trembled...so that the rocks fell down into the Valley from the surrounding cliffs". Earthquakes have rocked California for a lot longer than humans have been around, and no doubt played an important part in causing mass wasting within the valley. John Muir experienced the 1872 Lone Pine earthquake while in Yosemite Valley (magnitude 7.8 or higher) and witnessed the collapse of a cliff. I've witnessed a few small rockfalls that I will never forget. Imagine the impact of a really large quake and the accompanying rock falls on the collective memory of a people.

"The sky and mountains belched forth smoke and flame". Yosemite lies just west of the Long Valley Caldera and the Mono Craters, and eruptions have occurred there as recently as a few hundred years ago. Imagine the impact of a fair-sized eruption over the mountains on a people who maybe had never witnessed such a thing, or only heard about it in legends.

"The melting snows from the high mountains came down into the Valley in a flood and drowned hundreds of the people." It's not hard to imagine the impact of a Pineapple Express (an atmospheric river storm) falling onto a thick snowpack in the mountains above Yosemite Valley. Such an event took place in 1997 (be sure to check out the video). Much of the valley floor was covered by as much as 6-8 feet of water, and the event was devastating to the human developments in Yosemite Valley.


Ironically, the natural environment was far less devastated. The ecosystem of Yosemite evolved in an environment of occasional huge floods, and life sprang back quickly.

And, when the Valley was once again clothed in beauty and plenty, there appeared on the rent face of the dome which had been her home, the beautiful face of Tis-sa-ack, where it can still be seen to this day. And the dome was named Tis-sa-ack, in memory of the fair visitor who had been loved by all the people of Ah-wah-nee. At the same time, that all might hold his memory in their hearts, there appeared on the face of the great rock supporting his throne, the majestic figure of the great chief, dressed in a flowing robe and pointing a finger to where he had gone, to El-o-win, the happy land beyond the setting sun.

And thus we have the story of how Half Dome, Washington Column, and North Dome came to be. I am struck by how lifeless these names actually are, and I wish we could see their names changed to reflect the very interesting stories of their origins.

We have stories too of the formation of how these rocks came to be. They involve the formation of granitic magma deep in the hellish regions of the Earth's crust, the intrusion and cooling of the granite, the uplift and erosion of the rocks by rivers and glaciers, and the shaping of the rocks by the working of jointing, exfoliation, ice, and mass wasting. It's a good story, based on careful observations, but the ancient legends? They were based on careful observations as well. The Native Americans maybe didn't have the technology we have today, but they did a pretty good job of describing the phenomena, and designing models to explain their observations. 
 
This version of the Half Dome story is from The Lore and the Lure of The Yosemite by Herbert Earl Wilson, published in 1922. Another legend of Half Dome involves an argument between a husband and wife, with thrown baskets and other unpleasantness. I like the story above better!

What Lies Beneath Yellowstone? Yosemite, of course!

Upper Yosemite Falls, 1,250 feet high. Taken together the three components of Yosemite Falls amount to the fifth or seventh highest waterfall on the planet, at 1,425 feet (depending on who is measuring).

Okay, it's more fair to ask "what lies beneath Mt. Rainier or Crater Lake?". Yellowstone National Park sits atop a continental hot spot, and the plume of hot material will either explode out in a violent rhyolite tuff eruption, or cool deep underground into a granitic pluton. And Yosemite National Park exposes a great deal of granitic rock. But the origin of the granite at Yosemite is more related to arc magmatism, the formation of volcanic and plutonic rock as a plate of oceanic lithosphere sinks into the mantle beneath the edge of a continent. That's what is happening today in the Cascades, and it's what formed the famous volcanoes of that range: Rainier, Hood, St. Helens, Crater Lake, and more than a dozen others.

Lower Yosemite Falls, 320 feet high. Note the people for scale.

In a way, today's post is a sneak preview of the ending portion of my certain blog series on "Driving Through the Most Dangerous Plate Boundary in the World". The Franciscan subduction zone that was active during the Mesozoic Era was responsible for forming the Sierra Nevada batholith (batholith is a term for large bodies of magma, or a combination of numerous plutons in a region). The neat thing one can consider when visiting a Sierra Nevada park like Yosemite is that not only are you standing on the underside of former volcanoes and calderas, but you can also imagine the dinosaurs that once tromped around on the slopes of said volcanoes (we have even found fossils of a few of them, down in the sediments of the Great Valley)!

The Cathedral Rocks. Bridalveil Falls lie hidden on the other side.

I was in the valley again on Saturday, working through the onerous chore of dragging students around on a geology field trip. Somebody has to do it, after all. Buses can only stop in a couple of places around the valley floor, so we got off the bus and used the valley tram system to make a series of appointments at several spots in the valley to discuss the very cool geology.

The Middle Brother slide, from 1987. It is the largest slide in Yosemite's recorded history

Given a choice, I usually fore-go the tram in favor of walking to the appointment spots. It's not that I don't like the trams; they make a big difference in traffic congestion on the valley floor (you think it's crowded today? Imagine all the people on the trams in individual vehicles...). But because the trams make around thirty stops while traveling the loop of 8 or 9 miles, I can progress as fast or faster on foot. So I hoofed it from Yosemite Lodge to Happy Isles, a distance of about four miles. I had an hour and twenty minutes to get there, and I arrived with not a second to spare. But I saw marvelous sights along the way!

Yosemite Falls was at what may be the best flow it will have all year (top two photos). The drought left the park with 5% of its normal snowpack, and much or most of the ice is already flowing down the creeks and rivers. The falls will be dry in early summer.

I walked south from Yosemite Lodge where I had some very nice views of the Cathedral Rocks and the Middle Brothers Slide. The slide took place in 1987, and was the largest slope failure in Yosemite's recorded history, with over a million tons of rock.

Washington Column, the Royal Arches, and Clouds Rest

Washington Column, the Royal Arches, and Clouds Rest make for an awesomely steep gorge from the perspective of Swinging Bridge. The Bridge doesn't swing anymore, darn it! But it makes a nice platform for viewing Yosemite Falls and Yosemite Point from some distance away. The Merced River should be a bit more riotous at this time of year.

Yosemite Falls and the Merced River from Swinging Bridge

I added one small new section of trail to my experience this day. The Yosemite Loop trail travels the length of the valley on both sides, and I have walked most of it, but the section from the chapel to the LeConte Memorial Building was new to me. Despite the dry conditions, the forest floor was green and bursting with small white flowers.

From the south side of the valley, Washington Column stands as a bold cliff like the prow of a mighty battleship. It is shaped by joint fissures, large vertical cracks formed when the rock was exposed by erosion and expanded. North Dome, high above the Column, was formed by a similar process called exfoliation, where the rock expanded outwards, breaking off slabs that are parallel to the surface of the rock. The process tends to form domes all across the Sierra without the action of glacial erosion. The slabs formed by exfoliation can be dangerous to humans. In 1996, a slab the size of a football field came off the valley rim near Glacier Point, and collapsed on the valley floor near Happy Isles. The rocks killed one person and severely injured another. I was racing to the appointment at Happy Isles to show the students the site.

It was a beautiful day on the valley floor, and it was the first time some of my students had ever visited the park. That is one of the great privileges I have as a teacher of geology, introducing them to such a wonderful place, and providing an in-depth story explaining how the place came to exist. And dinosaurs!

If These Cliffs Could Talk: Tis-sa-ack and Tu-tok-a-nu-la (A Geologic Love Story)

Tis-sa-ack (Half Dome) from near Yosemite Falls

A love story...

Unnumbered snows have come and gone since The Great Spirit led a band of his favorite children into the mountains, and bade them rest in this beautiful Valley of Ah-wah-nee. They were weary and footsore, and were glad to rest after their long journey. Here they found food in abundance. The streams held swarms of fish, meadows were knee-deep in sweet clover, great herds of deer roamed the forests in the Valley, and on the high mountains, oak trees were bending under the weight of their acorns, grass seeds and wild fruits and berries grew in bountiful profusion. Here they stayed and built their villages. They were happy, and multiplied, and prospered and became a great nation.

North Dome, Washington Column, and Half Dome in the clouds

How many stories begin in paradise?

I find the myths of different cultures to be fascinating. They provided their people with an explanation of the unexplainable, a comforting story that suggests there is order in the apparent chaos of the universe. In the perspective of geology, we can sometimes see the whispers of eyewitnesses to significant geologic events: the eruption of Mt. Mazama, for instance, which resulted in the formation of Crater Lake, is described in Native American oral histories. In this post we see one of the legends of Yosemite Valley, with all the embellishments and cultural biases of a 1922 narrative. Still, it's a good story

To their chief came a little son to gladden his heart. They wanted this son to become a great chief, capable of the leadership of a great people. He was made to sleep in the robes of the skins of the beaver and the coyote, that he might grow wise in building and keen of scent. As he grew older he was fed the meat of the fish, that he might become a strong swimmer, and the flesh of the deer, that he might be light and swift of foot. He was made to eat the eggs of the great crane, that he might be keen of sight. He was wrapped in the skin of the monarch of the forest, the grizzly bear, that he might grow up fearless and strong in combat. 

So many stories come with the hero, and the most interesting stories have heroes with flaws...they had everything. But then things happen. The world and the people who live in it are not perfect. And frankly, life would not be interesting.

And, when he grew to manhood, he was a great chief and beloved of all the people. His people prepared for him a lofty throne on the crown of the great rock which guards The Gateway of the Valley, and he was called Tu-tok-a-nu-la, after the great cranes that lived in the meadow near the top. The people of Ah-wah-nee were happy, for Tu-tok-a-nu-la was a wise and a good ruler. From his high rocky throne he kept watch over the Valley and the people whom he loved. He called on The Great Spirit who sent timely rains, so that the acorns grew in abundance, the hunters returned from the forests with game, and the fishermen from the streams with fish. There was peace and plenty throughout the Valley of Ah-wah-nee, and when Tu-tok-a-nu-la held speech with his people from his high throne his voice was deep and strong like the deep sound of the waterfall.

Tis-sa-ack from Sentinel Bridge

But paradise can't last forever. Trouble was coming, or more to the point, the trouble lay hidden in the heart of the hero, and it was about to be made manifest. There were no doubt all kinds of communications between the many Native American bands in California, and the trading of knowledge and technology. I'm sure this led to problems at times as well.

One day as Tu-tok-a-nu-la sat gazing into the glowing colors of the west, he saw approaching his valley a strange people, led by a maiden of wondrous loveliness. He called to them and the maiden answered him, saying, "It is I, Tis-sa-ack. We have come from the land of my people in the far south to visit with you. We have heard of the great and good chief, Tu-tok-a-nu-la, of his great people and his wonderful valley. We bring presents of baskets and beads and skins. After we have rested we will return to my people in the far south." Tu-tok-a-nu-la welcomed the fair visitor from the land to the
south and had prepared for her and her people a home on the summit of the great dome at the eastern end of the Valley. There she stayed and taught the women of Ah-wah-nee the arts of her people. Tu-tok-a-nu-la visited her often in her mountain home. He was charmed by her wonderful beauty and sweetness, and begged her to stay and become his wife, but she denied him, saying: "No, I must soon return with my people to their home in the far south." And, when Tu-tok-a-nu-la grew importunate in his wooing, she left her home in the night and was never seen again.
 

To-ko-ya (North Dome), Nangas (Washington Column) and Tis-sa-ack (Half Dome) from Glacier Point. The Ahwiyah Point rockfall scar is visible just right of center below Half Dome.

The perfect women, the Helen of Troy, the Eve. Of course, perfection is a tricky concept, subject to many biases and assumptions. It doesn't much take into account the actual relationship between those involved. As Mr. Spock mentioned in a famous episode of Star Trek: "After a time, you may find that having is not so pleasing a thing after all as wanting". Bad things are about to happen.

I admit, I've never heard the word importunate before. 

When the great chief knew that she was gone, a terrible loneliness and sorrow came to him, and he wandered away through the forests in search of her, forgetting his people in Ah-wah-nee. So strong was his love for her, and so deep his sorrow, that he forgot to call upon The Great Spirit to send the timely rains. So great was his neglect that the streams grew smaller and smaller and finally became dry. The crops failed. The hunters came back from the forests without meat, and the fishermen returned from the streams empty-handed. The leaves and the green acorns fell from the trees, and the bright flowers and green grasses became dry and brown.

From Washburn Point it is obvious that Half Dome isn't just a boring name, it is a mathematically wrong name. Three-Quarter Dome, maybe. I would just go with Tis-sa-ack

This is where the geologist in me starts paying attention. California has droughts, and there is evidence of mega-droughts that lasted more than a century. Check out this post for some of the striking evidence. These droughts both occurred within the last 2,000 years, recently enough to be remembered in the oral histories of a people.

And then things get interesting in a hurry...

The Great Spirit became very angry with Tu-tok-a-nu-la. The earth trembled with his wrath so that the rocks fell down into the Valley from the surrounding cliffs. The sky and the mountains belched forth smoke and flame. The great dome that had been the home of Tis-sa-ack, was rent asunder and half of it fell into the Valley. The melting snows from the high mountains came down into the Valley in a flood and drowned hundreds of the people. But the wrath of The Great Spirit was quickly spent, and the heavens again grew quiet. The floods receded, the sun shone, and once more peace and calm reigned over Ah-wah-nee. The life-giving moisture from the renewed streams crept into the parched soil. The oak trees put on new leaves and acorns. The grasses again became fresh and green, the flowers lifted their drooping heads and took on their old gay colors. The fish came back to the streams, and the game to the forests.

Wow.

"The earth trembled...so that the rocks fell down into the Valley from the surrounding cliffs". Earthquakes have rocked California for a lot longer than humans have been around, and no doubt played an important part in causing mass wasting within the valley. John Muir experienced the 1872 Lone Pine earthquake while in Yosemite Valley (magnitude 7.8 or higher) and witnessed the collapse of a cliff. I've witnessed a few small rockfalls that I will never forget. Imagine the impact of a really large quake and the accompanying rock falls on the collective memory of a people.

"The sky and mountains belched forth smoke and flame". Yosemite lies just west of the Long Valley Caldera and the Mono Craters, and eruptions have occurred there as recently as a few hundred years ago. Imagine the impact of a fair-sized eruption over the mountains on a people who maybe had never witnessed such a thing, or only heard about it in legends.

"The melting snows from the high mountains came down into the Valley in a flood and drowned hundreds of the people." It's not hard to imagine the impact of a Pineapple Express (an atmospheric river storm) falling onto a thick snowpack in the mountains above Yosemite Valley. Such an event took place in 1997 (be sure to check out the video). Much of the valley floor was covered by as much as 6-8 feet of water, and the event was devastating to the human developments in Yosemite Valley.


Ironically, the natural environment was far less devastated. The ecosystem of Yosemite evolved in an environment of occasional huge floods, and life sprang back quickly.

And, when the Valley was once again clothed in beauty and plenty, there appeared on the rent face of the dome which had been her home, the beautiful face of Tis-sa-ack, where it can still be seen to this day. And the dome was named Tis-sa-ack, in memory of the fair visitor who had been loved by all the people of Ah-wah-nee. At the same time, that all might hold his memory in their hearts, there appeared on the face of the great rock supporting his throne, the majestic figure of the great chief, dressed in a flowing robe and pointing a finger to where he had gone, to El-o-win, the happy land beyond the setting sun.

And thus we have the story of how Half Dome, Washington Column, and North Dome came to be. I am struck by how lifeless these names actually are, and I wish we could see their names changed to reflect the very interesting stories of their origins.

We have stories too of the formation of how these rocks came to be. They involve the formation of granitic magma deep in the hellish regions of the Earth's crust, the intrusion and cooling of the granite, the uplift and erosion of the rocks by rivers and glaciers, and the shaping of the rocks by the working of jointing, exfoliation, ice, and mass wasting. It's a good story, based on careful observations, but the ancient legends? They were based on careful observations as well. The Native Americans maybe didn't have the technology we have today, but they did a pretty good job of describing the phenomena, and designing models to explain their observations. 
 
This version of the Half Dome story is from The Lore and the Lure of The Yosemite by Herbert Earl Wilson, published in 1922. Another legend of Half Dome involves an argument between a husband and wife, with thrown baskets and other unpleasantness. I like the story above better!

The Way it Was Today: Yosemite Valley in November

What a wonderful week! I had the privilege of visiting the most beautiful place in the world twice in the space of a few days. It's true I was taking a bunch of students with me, but we were learning geology in one of the most spectacular settings possible and it was a fine and enthusiastic group. For some it was their first visit to the valley. For others it was the first time seeing the place in a geological sense.

It was an eventful week as well. A storm blew through, leaving a few inches of snow in the valley, but it was all but gone by the time we arrived this morning. Last week there were lots of leaves on the trees in full glory of color, but things were dusty. Today the ground and air were moist, the forest smelled sweet, but there were fewer leaves on the trees.

Our first stop was to visit the Tunnel View, a spot just a few hundred feet below where the valley was first discovered by Europeans in 1851. There was trouble between American settlers and the local Native Americans, so a militia had been raised to search them out. Their medical officer Lafayette Bunnell was entranced with the valley and wrote a glowing account of its beauty.

I seemed to be concentrating on Half Dome a lot today. We had arrived in a large bus, and buses aren't allowed to park in many parts of the valley, so we toured on the free trams with appointments to meet at several locations. I elected to walk between points, and had a few new angles with which to view the iconic chunk of granitic rock (granodiorite, to be specific).

Despite the appearance, the dome is not really in half. It might be more properly called Three-Quarter Dome, although I prefer the Native American name of Tis-sa-ack. The south east flank is a classic exfoliation dome, shaped by the slabbing off of the corners and edges in response to the release of pressure as the rock was exposed by erosion. The steep northwest face is a joint surface that was exploited by glaciers that flowed beneath the face of the dome.

There are other lesser known domes, such as North Dome, seen below. It is the rounded edge of a long ridge of granitic rock. Like Half Dome, it was formed by exfoliation. Glacial ice never covered it. North Dome lies above Tenaya Creek, across from the face of Half Dome.

I was walking from Yosemite Lodge to Happy Isles. I started by wandering through the forest in an unfamiliar direction and almost immediately discovered the central receiving facility for all the raw sewage in the valley (I don't know this for sure, as the building was locked and unlabeled, but the stench was convincing). I reconsidered my route and headed out to the meadow near Sentinel Bridge. I was rewarded with a beautiful panorama of the Cathedral Rocks and the Three Brothers (below).

I said there were fewer leaves, but they certainly weren't gone by any means. Fewer leaves means that the remaining ones stood out in bolder relief.

The Merced River continues its late season serenity. Low flows provide marvelous reflective properties. The picture below is from a stretch of the river just downstream of the tent cabins at Curry Village.

The ravens were out in force. I stopped for a snack and they were flanking me. When I got up to discard my trash, they were thinking about seeing what was left in my pack. I found myself imagining that they will be the next truly intelligent being to evolve after we humans are gone. Like us, they seem capable of surviving practically anywhere (the deserts of Death Valley to the high peaks of the Sierra Nevada and across the desert southwest), and they are probably already smarter than the average touron in Yosemite (it's how they stay fed).

After meeting with the students at Happy Isles, we started back across the valley to Yosemite Lodge. I decided to walk and see if I could beat the tram. I did, by about 10 seconds (Unlike the tram, I didn't have to stop, and I could take the shortest route along roads and trails). I snapped a few shots while rushing along the road. Below is another view of North Dome, and a side of the Royal Arches, a form of exfoliation in reverse.

Washington Column is a steep cliff that overlooks the Mirror Lake area. The largest slide known from Yosemite Valley occurred here a few thousand years ago, forming the lake (that is a lake only seasonally). It may have been about twenty times larger than the biggest historical mass wasting event, the Middle Brother slide of 1987, which involved 600,000 cubic yards of granitic rock.

As I got closer to our final stop, I had one more wonderful view of Half Dome. The late afternoon sun was casting dappled shadows across the meadow. It was another beautiful day in a wonderful place. In a few more short weeks it will be winter!

A Beautiful and Precious Day: How it was today in Yosemite

OK, I'm waxing a little poetic today, but let me give you some background. Got to sleep late last night in the middle of a rainstorm, got up miserably early to see the rain continuing, and a check of the weather radar said it was still raining up in Yosemite National Park, which was the destination of our class field trip today. Drove to school during the gloom, gathered up the students into the bus, and we drove off into the rain. I've often said that Yosemite has a uniqueness that transcends bad weather, but not when I'm dragging a bunch of not-necessarily enthusiastic sleepy students.

And that's why today was precious...
By the time we reached Yosemite Valley early in the afternoon, the clouds were breaking up, and we were witness to a stunning view of rain-washed cliffs and roaring waterfalls. In many Octobers, the valley is dry and dusty, tired after a summer onslaught of millions of tourists. Above, North Dome and Washington Column are framed by bright blue sky. North Dome is a classic example of exfoliation weathering: as the rock was exposed by erosion, it expanded outward, cracking and forming slabs that ultimately slid off. The effect was to remove corners and edges.

Half Dome spent much of the day with a crown of clouds, but by afternoon it joined the skyline. Half Dome would have been best named Four-Fifths Dome, but I prefer the Native American name: Tis-sa-ack. Like North Dome, Half Dome was never covered by glacial ice, but instead was shaped by exfoliation. A prominent joint on the north face was quarried by glacial ice flowing along the base.

The rain this month was more than normal, and the rivers have started flowing early. Yosemite Falls looked more like early summer than the middle of fall. The falls are a classic example of a glacial hanging valley. Lower Yosemite Falls drop 318 feet almost to the valley floor. They are easily accessible by way of a short trail. Although it is not at all recommended, and people are constantly getting injured, climbing around on the falls is a common occurrence. At least they provide a sense of scale in the photo above.

From the Wawona Tunnel exit, the view is almost always indescribable, and I can never resist taking a bunch of photos. I try to bring out different perspectives, and today Half Dome was obscured by clouds, and shadows accentuated the flatness of the valley floor. I shot a bit to the right, removing El Capitan from the picture as well. Sentinel Rock and the Cathedral Rocks become the dominant cliffs from this perspective.

I had a chance to walk from Yosemite Falls to Happy Isles, a traverse of about 4 miles on the Valley Loop Trail. It was amazingly bereft of people, to the extent that I actually started to worry a little about mountain lions lurking atop the giant boulders that line the trail. The river crossings showed how much water was moving through the valley. Tenaya Creek (above) is usually almost dry.

My poor students, forced as they were to attend a required class field trip, dutifully took notes, and pretended to be interested. I think they had some fun while they were learning, though. For myself, I felt privileged to be in such a beautiful and stunning place...

Staring into the Abyss #4 - Yosemite as you (maybe) have never seen it (and my 100th Post!)

Today is the four-month anniversary and the 100th post on Geotripper! I wasn't really sure what it was going to be like, and whether I would be able to keep the site active with all of the other stuff going on in my life as a college teacher, but I have made it work by allowing myself a blog entry as a reward for finishing a pile of grading. And there are always piles of grading! But I have enjoyed sharing my photographs and opinions, and I have especially appreciated the positive feedback that I have received from the geoblogosphere. I enjoy being a part this interesting group of earth scientists, and I hope to see more of the students and teachers out there getting involved! It was far easier to start a blog than I thought it would be and it has been rewarding. Now I will have to see if I can make it all the way through a year!

Today's view of the abyss comes from a familiar tourist stop: Glacier Point. It is accessible by paved road and trail, and is visited by hundreds of thousands of people every year. It is easily one of the greatest scenic vistas on the planet. The view is dominated by Half Dome and the Tenaya Canyon, as well as the cliffs around Yosemite Falls. Between the two is an interesting view of a pair of exfoliation domes called North Dome (left) and Basket Dome (right). From the valley floor they are barely visible above Royal Arches and Washington Column.

Exfoliation takes place when the weight is removed from homogeneous rock like granite, and the rock expands. It fractures parallel to the surface and this leads to a tendency to remove corners and edges of otherwise rectangular rocks. A great many domes grace the Sierra Nevada, and a vast number of them have never been touched by glaciers.

The mountain on the skyline is Mt. Hoffman, which is a high peak close to the geographic center of Yosemite National Park. N. King Huber used the view from the summit as the springboard to a discussion of the geology of the park in his excellent Geologic Story of Yosemite National Park. It is a great hike, and is likely to be the subject of future posts.