If These Cliffs Could Talk: The Cliffs of the Ah-wah-nee that Never Got Legends

Do you know these places? Would a place that has cliffs like these merit being declared a national park?

Thankfully, these rocky precipices are in a national park already. But these are not the iconic features that end up in the photo collections of the millions of tourists that visit this place every year. But these cliffs contribute to the awesome scenery by serving as the backdrop for some very famous rocks. They serve as the supporting chorus behind the hardrock band, so to speak. They are the unsung cliffs of Yosemite Valley (the Ah-wah-nee). As far as I know, few of these escarpments have a mythical legend that celebrates their existence.

If these cliffs of Yosemite Valley could talk, they would have something to say about my recent little miniseries on the most famous rocks that can be seen from the valley floor. They would say "but, none of these cliffs could be famous without the un-famous cliffs and slopes that lay between".

The first picture in this post has a waterfall that is usually dry by the time most tourists begin arriving in June or July. When it is running it is often mistaken for Yosemite Falls by first-time visitors (until they see Yosemite Falls anyway). It is Ribbon Falls, which is actually the waterfall at Yosemite with the greatest unbroken drop (1,612 feet; 491 meters). Compare that to Upper Yosemite Falls at 1,430 feet (436 meters). The total drop of the three steps of Yosemite Falls totals 2,425 feet (735 meters), making the better-known fall one of the top ten highest falls in the world. Ribbon is apparently 99th. But imagine if it were the only fall at Yosemite. How famous it would be! It doesn't always get noticed because it lies just west of the boldest cliff of El Capitan.

The cliff in the picture above is an unnamed spire in the vicinity of Sentinel Rock. Although the cliff is thousands of feet tall, it is less imposing than Sentinel because it is more highly jointed (fractured). The rocks have been darkened by lichens and staining and thus appear darker than most of the granite cliffs (fresh exposures from more recent rockfalls reveal the lighter rock).

The partly rounded rock on the left in the picture above is the familiar Leaning Tower, although the lean is not so prominent from this angle. The rugged cliffs on the right include Dewey, Crocker, and Stanford Points, but the cliffs have no particular name. Like the previous photo, the rocks are more highly jointed, resulting in a recessed cliff face with talus (slopes of fallen boulders) covering the lower portions.

To me, one of the most striking features of Yosemite Valley is the total non-cliff that lies just west of Ribbon Falls and El Capitan. Instead of a vertical precipice, the slope is almost entirely buried in talus from the constant collapse of what cliffs there are. The dark-colored plutonic rock is called, not too surprisingly, the Diorite of the Rockslides. It is the most highly jointed of all the rocks in Yosemite Valley.

The next picture is a familiar view to anyone who has visited Glacier Point. Yosemite Falls is apparent on the left, and the Royal Arches are partly visible on the right, but the cliffs in-between are less familiar, in part because of the intense jointing that has led to a less bold appearance. The deep cleft in the center of the photo is Indian Creek, and the crenelated cliffs to the left of the creek are called the Castle Cliffs.

Panorama Cliff appears in many photographs taken from the vicinity of the Ahwahnee Hotel, but few know the name. It forms the south wall of the Merced River canyon where it emerges from Little Yosemite Valley.

One would think that waterfalls thousands of feet high would get more attention, but these two are very seasonal, generally drying up by late May or early June. The one above is the Widow's Tears, a 1,170 foot high waterfall tucked into the cliffs near Crocker and Stanford Points west of Leaning Tower. It has been mistaken for and mislabeled as Silver Strand Fall, which is much shorter.

And finally, there is Sentinel Falls, a 1,920 ft (590 m) fall on the west flank of Sentinel Rock. Like the other less famous waterfalls, it is ephemeral, and often dry by early summer. The biggest drop among the many cascades is about 500 feet high.

Light and shadow. Positive and negative.Yin and yang.

Mrs. Geotripper, the artist, tells me that yin and yang can be thought of as complementary (rather than opposing) forces that interact to form a dynamic system in which the whole is greater than the assembled parts. That is what these cliffs accomplish at Yosemite Valley. For every bold cliff like El Capitan, Half Dome, or Sentinel Rock, there are recessed cliffs that lie in the shadows. Hidden among these recessed cliffs are beautiful waterfalls that during the right time of year rank as some of the world's highest and most dramatic. If we could just find them among the richness of features at Yosemite Valley!

If These Cliffs Could Talk: Leaning Tower and Bridalveil Fall in Yosemite

Bridalveil Fall and Leaning Tower on Sunday afternoon

Nature abhors cliffs as a general rule. Gravity dictates that cliffs will be a rarity in most parts of the world, because most rocks are simply not capable of resisting the intense stresses the cliffs cause. The cliffs of Yosemite are thus extraordinary, because they are among the highest in the world. The reason, of course, is because they are composed of extraordinary rock.

The subterranean world beneath an active volcano is a place from which the imagery of hell has been drawn. Seething hot magma pulses upwards through the crust, invading every crack and fissure, wedging rocks apart, and occasionally breaking through and producing catastrophic volcanic eruptions. But eventually the volcanic system becomes inactive, and the magma chambers eventually, and slowly, cool down. The silicate-based chemical stew starts to crystallize, and the interlocking crystals produce extremely strong rocks with names like granite, diorite, tonalite, and granodiorite. The rocks vary by (and are defined by) the percentages of quartz, plagioclase feldspar and orthoclase feldspar. Other accessory minerals, the dark ones like hornblende or biotite mica, give the resulting rock the characteristic speckled appearance. In a general way, the granite is lighter in overall appearance while the others are somewhat darker. These are the kinds of rocks that can stand in high vertical cliffs.

But other things have to happen to make cliffs. Normal river erosion tends to produce slopes, not sheer cliffs. Yosemite Valley was once a deep river-cut canyon, but the slopes would have been unremarkable, steeply sloping, but probably covered with talus (rocky debris) and vegetation. The lower Merced River canyon (below) provides a hint of how it might have looked: deep and rugged, but not the sheer cliffs of Yosemite. One of the factors is ice.

Conditions in the Sierra Nevada changed starting about two million years ago. The climate worldwide went through a series of cooling periods, and ice sheets covered much of North America and Europe. The climate would warm up again, the ice would recede, and then cooling would return. Perhaps a dozen ice ages took place, the most recent ending only around 12,000 years ago.

The ice did not cover the entire Sierra Nevada, nor did it cover the tops of the high peaks along the crest. The glaciers were confined for the most part to the valley floors, where the ice plucked boulders and abraded surfaces, eventually producing U-shaped valleys. There is direct evidence of at least three glacial episodes that scoured Yosemite Valley, the Pre-Tahoe (somewhere around 800,000 to 1 million years ago), the Tahoe (several pulses between about 160,000-65,000 years ago), and the Tioga (about 13,000-20,000 years ago).

And yet ice needs some help when attacking such hard rock. There have to be fractures and fissures for the ice to exploit before serious quarrying can take place. And that is where jointing and exfoliation come into the picture.

Intersecting joint sets in Tokopah Valley, Sequoia National Park

Granitic rocks cool at depths of several miles within the crust. Pressure is high at such depths, and so as the rocks are lifted towards the surface and exposed by erosion, they expand and fracture. Fractures that occur parallel to the surface are called exfoliation sheets. More or less vertical fractures, which may form from subtle extensional or compressional forces, are called joints. Joint sets can form in several directions as seen in the images above and below.

Intersecting joint sets in Joshua Tree National Park, southern California

Closely jointed rocks are readily excavated by glaciers, while more widely jointed rocks are not. Yosemite Valley, with ten different intrusions of granitic rock, exhibits wide variation in susceptibility to erosion, so that some units tend to form recessed slopes (i.e. the Diorite of the Rockslides), while other rocks tend to form bold cliffs such as El Capitan (the El Capitan granite).

I'm back from my first Yosemite trips in a number of  months, so I would like to share a couple of cliffs with you in the next couple of posts! I was going to call this mini-series "If These Walls Could Talk", but a short search revealed that naturalists at Yosemite are already using that title! So, I've modified it just a bit.

The cliff of the day is the one that extends from Bridalveil Fall to the Leaning Tower. Bridalveil Fall is a classic example of a glacial hanging valley that formed when the main Merced glacier cut a deeper valley than the smaller tributary glacier in Bridalveil Creek. The waterfall drops 620 feet, and runs pretty much all year, though in the autumn it is often just a trickle, as can be seen in the top photo of this post. 

In the spring runoff, the fall is spectacular. A couple of years back, in the blissful pre-drought days, I caught a rainbow in the spray coming of the base of the fall.

The Leaning Tower is composed of several kinds of rock, including the El Capitan granite and the Leaning Tower granodiorite. The granite is about 103 million years old, and the granodiorite somewhat younger, although a precise age hasn't been determined that I can find. The most remarkable feature of the Leaning Tower is...it leans! The cliff prominently hangs out over the valley below. El Capitan does this as well, but it isn't so easily seen. The cliff is one of the more popular climbs in the valley.

Next post: what's on the other side of Bridalveil Falls?

If These Cliffs Could Talk: A Sentinel People Sometimes Miss in Yosemite

If you saw this picture out of context, perhaps in the opening frames of an adventure movie, you might think of this cliff as being an otherworldly precipice full of allure and mystery. Maybe dragons perch on its summit, maybe buried treasure lies in a cave at its base. It's an incredible rock tower.

To back up and look at this cloud filled world from a distance takes away none of the mystery. Here is a spectacularly deep gorge with dark forested slopes and vertical rock cliffs. What kind of place is this? Who's been keeping it such a secret? Shouldn't it be a national park or something?

Well, actually it is, and upwards of four million people look at this cliff tower every year. They just don't quite see it as it gets lost in the multitudes of other more iconic cliffs like Half Dome, El Capitan, and Cathedral Rocks. Half Dome would be in the picture above were it not for the clouds.

We are looking at Sentinel Rock, and it is the hard-to-see tower in the dead center of the picture below. Can you see how easy it is to lose it in the grandeur of the cliffs that surround it on all sides? I was taking advantage of the cloud cover to get a photo from Tunnel View that highlights the cliff.

How could you miss it? It's in the dead center of the photograph! (May 2014)

Sentinel Rock is composed of the Sentinel Granodiorite, which was intruded about 95 million years ago, making it one of the younger intrusive rocks exposed in Yosemite Valley.It is a gray colored rock composed mostly of plagioclase feldspar with lesser amounts of orthoclase feldspar and quartz. The black specks in the rock are biotite mica and hornblende.

As pointed out in the previous posts of this short series on the cliffs of Yosemite Valley, joints are vertical or nearly vertical fractures that can result from stresses on the rock at shallow depths in the crust. Rocks like the Half Dome granodiorite and El Capitan granite are sparsely jointed and stand as bold cliffs that stand out from the valley walls. The Sentinel granodiorite is somewhat more jointed, so it stands more as a tower than a large cliff. It is surrounded by spires and fissures, including the Taft Fissures that can be accessed by trail above the rim of the valley.

Sentinel Rock soars 3,000 feet above the valley floor with an elevation of 7,038 ft (2,165 m). It is a popular climbing challenge. No trails reach the summit, but the Four-Mile Trail to Glacier Point winds across the slopes below. There is a separate peak called Sentinel Dome behind the rim above Sentinel Rock that is a popular hiking destination.

Sentinel stands out in the boldest relief when viewed from Cook Meadow where most everyone stares at Yosemite Falls directly across the canyon. If you are ever lucky enough to visit Yosemite and are standing in awe below the falls, don't forget to look behind you!

There are several other pullouts on the valley loop road that offer good viewpoints, especially with the Merced River in the foreground. If you've been up the Four-Mile Trail or the trail to Yosemite Falls, I'd love to see some of your pictures! I hate to say it, but I've been halfway up the falls trail, snapping pictures right and left, but I didn't get a single shot of Sentinel. Half Dome, yes. Yosemite Falls, upper, middle and lower, yes, selfies, yes, but no Sentinel. It hides in plain sight.

A wonderful rock!

If These Cliffs Could Talk: The Cathedral Rocks vs.the Cathedral Spires

Cathedral Rocks and Bridalveil Fall from the Gateway View (April 2014)

Yosemite Valley has such a richness of sheer and spectacular cliffs that I imagine any one of them would rate being a national park or monument of its own in any other setting. Looking at the most famous cliffs, one can be distracted from recognizing the awesomeness of cliffs that loom behind. . We began yesterday with a look at Leaning Tower and Bridalveil Fall at the west end of Yosemite Valley on the south side of the canyon. These rocks are familiar because they are often the first to be encountered when one arrives at Yosemite for the first time. Bridalveil Fall is visible from the Tunnel View, and is the first major parking area when starting the valley loop road.

Today's cliffs are the Cathedral Rocks and Cathedral Spires. The Cathedral Rocks are as familiar as Bridalveil, as they provide the backdrop to the falls (above). There are three prominent triangular peaks. From the Tunnel View or from the Valley View turnout they are spectacular, but are not vertical cliffs. To get that perspective, you'll have to walk or drive east of Bridalveil Falls. Things get very steep in a hurry.

The Cathedral Spires and the Merced River, November 2014

One of the first things to note is that the Cathedral Rocks and Cathedral Spires are two different features. The spires are a pair of prominent towers of rock tucked into a recess just east of the Cathedral Rocks. The imposing towers are composed of the very tough El Capitan granite, but are separated by exposures of the highly jointed Diorite of the Rockslides, a rock that is subject to mass wasting (rock falls and slides).

Spires like these are usually found along the rim of Yosemite Valley, high above the valley floor, as they are easy targets for removal by glacial ice. The later ice ages, the Tahoe and Tioga stages, did not come close to filling the valley at this locale, and thus were not able to strip away the narrow fissured towers.

The Cathedral Spires, November 2014

The Cathedral Rocks, when viewed from other angles in Yosemite Valley, are simply stunning. I was lucky to show up in Yosemite in January 2011 on the heels of an intense snowstorm. Snow was literally clinging to the cliffs in the late afternoon, and the winds had died down, leaving a mirror-like lake in one of the meadows, with a cold mist rising. It's one of my favorite pictures (below).

Cathedral Rocks in January 2011, from near Leidig Meadow

Another perspective is provided by the trail that winds east from Bridalveil Fall. It follows the base of the sheer cliff, an angle hard to capture in a photograph.

Does it look to you like the dead stump in the foreground is holding back a really big boulder?

The cliffs are visible from several other meadows, although people are sometimes distracted by the views of El Capitan or Yosemite Falls. The picture below is from Cook Meadow, which is better known for the spectacular view of Yosemite Falls and the Three Brothers.

Cathedral Rocks from Cook Meadow

Finally, one should never forget that there are places where you can look down into Yosemite Valley. A drive to Glacier Point is never a wasted day, but one should set aside some time to take a couple of short trails to the rim, including Sentinel Dome, and Taft Point. Taft Point in particular offers a wonderful view of the Cathedral Rocks from above. It is from here that one gains a real appreciation for how tough the El Capitan granite truly is. The rocks project well into the valley, forming a narrow passageway between Cathedral Rocks and El Capitan. The valley is barely 2,500 feet across at this point. El Capitan rises 3,000 feet on the one side, while the Cathedral Rocks loom 2,600 feet above. At this point the canyon is deeper than it is wide!

If These Cliffs Could Talk: Wa-ha'-ka, the Three Brothers Who Are All Out of Joint

Actually the Three Brothers are just full of joints, and that's the problem.

If any legends exist concerning the rocks known as the Three Brothers in Yosemite Valley, they have not come to me via the anthropologists or the internet. The rocks seem have been called Wa-ha'-ka, Wawhawke, or Kom-po-pai-zes, with meanings that include leaping frogs, couples enjoying each other (to use a family-friendly description), or the one that makes the most sense to geologists, "falling rocks". Rocks fall in Yosemite on a constant basis, but the Three Brothers are prizewinners in that regard.

The rather boring English name came from a historical event when James Savage's militia (the Mariposa Battalion) caught up to three of Chief Tenaya's sons near the base of the rock in 1851. It's a pretty mundane name, and I would really love to see a campaign started to officially re-name all of Yosemite's most prominent rocks with their ancestral First Nation monikers.

In any case, Wa-ha'-ka is a unique cliff for the three striking peaks, Eagle (the highest), Middle Brother, and Lower Brother. The triangular shape is derived from the joint pattern that courses through the cliffs. As mentioned previously in this short blog miniseries on Yosemite, joints are the fractures that occur in granitic rocks as they reach the surface and come under lateral pressure from nearby fault zones or regional stresses. There are two intersecting joint systems that formed the Three Brothers, one descending about a 60 degree angle. It can be seen best from across the valley at Taft Point, and the related Taft Fissures. The joints run through El Capitan granite and Sentinel granodiorite.

The Three Brothers and Yosemite Falls from Taft Point

Notice in the photo below how the slope in the foreground near Taft Point is angled the same direction as the joints at Three Brothers across the valley. There are many good reasons to make the short hike out to Taft Point, and this is one of them.

There is a very good reason thinking that First Nation name of the rock means "falling rocks". Crossing joints provide the instability that leads to slope failure. The rocks here fall often, and indeed in 1987, the largest recorded rockfall in recorded history at Yosemite took place at the base of Middle Brother. Thankfully the park road had been closed as a precaution and no one was hurt.

The Middle Brother Slide

The park historian at the time, Jim Snyder, was standing in the meadow below and described what happened (from Wieczorek et al., 1992*):

At 2:47 p.m. PST on March 10, 1987, a large rock fall dropped 800 m from the face of Middle Brother and spread rapidly across a talus cone, covered Northside Drive, and sent boulders across the Merced River. Much smaller rock falls from Middle Brother had begun on March 8, and by about 2:20 p.m. on March 10, because of an increasing number of rock falls and audible rock popping noises from the face of Middle Brother, Northside Drive, the main exit road from the valley, had been closed and the portion of Leidig Meadow below Middle Brother had been cordoned off.

...Jim Snyder observed the rock fall initiate as an intact planar slab of rock that separated from the cliff face. As the slab fell it appeared to shorten in a folding-like manner similar to the steps of an escalator. The slab disaggregated into a rock avalanche upon hitting and sliding along a prominent ledge before falling onto the talus cone below.

Another large rock fall from the face of Middle Brother occurred later that day at 5:10 p.m. The volume of these rock falls totaled an estimated 600,000 cubic meters of material weighing about 1.3 million metric tons. Dozens of smaller rock falls continued during the next several days..."

*Wieczorek, G.F., Snyder, J.B., Alger, C.S., and Isaacson, K.A., 1992, Rock Falls in Yosemite Valley, California, U.S. Geological Survey Open File Report 92-387, 186 pages.

If These Cliffs Could Talk: The Legend of Kos-su-kah, Tee-hee-nay, and Hum-mo in the Valley of the Ah-wah-nee

 

I've done a lot of traveling in the last month, from Arizona and back, to Pinnacles National Park, and then through Northern California to the Oregon Coast. In the blogging sense, I got distracted from a little mini-blog-series I was doing on Yosemite Valley, but today we're back among some of the most beautiful cliffs in the world.

There is a spire kind of hidden in plain view among the high precipices near Yosemite Falls, the Three Brothers and Yosemite Point. It's more prominent from some angles than others, but it helps if some clouds are pouring over the high cliffs, defining it. The spire is called the Lost Arrow. It formed in the El Capitan granite and Sentinel granodiorite where vertical joints have caused the rocks around the spire to fall away (joints are straight fractures in the rock caused by the release of pressure as the rocks are exposed by erosion).

This is what joints look like if there isn't an adjacent 3,000 foot cliff (Tokopah Valley in Sequoia National Park)

As with many of the distinctive rocks of the valley, there is a Miwok legend told of it, not so much as its origin, but of an event to which it is related. As I read this narrative, I was struck by the sensitivity and heart of the story. It has a bit less of the fantastical mythological aspects that often accompany such stories, and thus in a way seems grounded in possible real events. In a biblical setting, this would be like comparing the narratives of Genesis floods and Egyptian Plagues with their apocalyptic themes to the later stories of King David and his relationships with Jonathan or Bathsheba. Or maybe the narratives concerning Ruth and Boaz.

We pick up the story as it is related by Galen Clark in The Indians of the Yosemite Valley and Vicinity (1904):

Tee-hee'-nay was a beautiful Ah-wah-nee maiden, said to be the most beautiful of her tribe, and she was beloved by Kos-su'-kah, a strong and valiant young brave. Valuable presents had been made to the bride's parents, and they had given their consent to an early marriage, which was to be celebrated by a great feast.

To provide an abundance of venison and other meat for this banquet, Kos-su'-kah gathered together his young companions and went into the mountains in search of game. In order that Tee-hee'-nay might know of his welfare and the success of the hunt, it was agreed between the lovers that at sunset Kos-su'-kah should go to the high rock to the east of Cho'-lack (Yosemite Falls), and should shoot an arrow into the Valley, to which should be attached a number of grouse feathers corresponding to the number of deer that had fallen before the skill of the hunters.

At the time appointed Tee-hee'-nay went near the foot of the great cliff and waited, with her eyes raised to the towering rocks above, hoping with her keen sight to see the form of her lover outlined against the sky, but no form could she see, and no arrow fell into the Valley. As darkness gathered, gloomy forebodings took possession of her, and she climbed part way up the canyon called Le-ham'-i-tee because the arrow-wood grew there, and finally she stood at the very foot of the rocky wall which rose to dizzy heights above her, and there she waited through the long night.

The Miwoks and other First Nation people who utilized Yosemite Valley for thousands of years no doubt had a good understanding of the geologic hazards of the valley. In about eighty visits to Yosemite Valley, I've seen two rockfalls, and heard several others. They are common events in the glacially steepened valley. Joints and exfoliation fractures provide the loosened rock, while ice wedging or earthquakes provide the tipping point that sends the rocks plummeting to the valley floor.

With the first streak of dawn she bounded swiftly up the rough canyon, for she was fully convinced that some terrible fate had overtaken the brave Kos-su'-kah, and soon she -stood upon the lofty summit, where she found her lover's footsteps leading towards the edge of the precipice. Drawing nearer she was startled to find that a portion of the cliff had given way, and, upon peering over the brink, what was her horror to discover the blood-stained and lifeless body of Kos-su'-kah lying on a rocky ledge far beneath.

Summoning assistance by means of a signal fire, which was seen from the Valley below, a rope was made of sapling tamaracks lashed firmly together with thongs from one of the deer that was to have furnished the marriage feast, and Tee-hee'-nay herself insisted on being lowered over the precipice to recover the body of her lover. This was at last successfully accomplished, and when his ghastly form lay once more upon the rocky summit, she threw herself on his bosom and gave way to a passionate outburst of grief.

Finally she became quiet, but when they stooped to raise her they found that her spirit had fled to join the lost Kos-su'-kah, and that the lovers were re-united in death.

The fateful arrow that was the cause of so much sorrow could never be found, and the Indians believe that it was taken away by the spirits of Kos-su'-kah and Tee-hee'-nay. In memory of them, and of this tragedy, the slender spire of rock that rises heavenward near the top of the cliff at this point is known among the Indians as Hum-mo', or the Lost Arrow.

There are so many elements of humanity in this legend, even to the echoes of the ending of Romeo and Juliet (there is also a favorite folk song of the eastern Sierra Nevada with a similar tragic ending: Darcy Farrow). After all, what is the role of a myth but to teach us about life, both the happy parts and the tragic ones? This is one of my favorite Sierra legends.

I couldn't help but notice that in the legend it is a remarkable thing to have descended a vertical cliff, something that today is considered a form of recreation. One year I caught sight of someone tight-rope walking from the Lost Arrow back to the main cliff. Times are different...

If These Cliffs Could Talk: The Ah-wah-nee, To-tau-kon-nu'-la, and a Different History of the Sierra Nevada

The first question might be "what is that?". It's a pair of climbers, Kevin Jorgeson and Tommy Caldwell, on El Capitan (To-tau-kon-nu'-la) in Yosemite Valley (Ah-wah-nee) who are seeking to do something never before done...a free climb of the one of the most difficult rock faces in the world. Free climbing means they do the climb with their hands and legs only, not using artificial supports. It's not entirely insane, as they wear rope harnesses to protect them from falls, which they do a lot. In any case, their effort has made it into the national media. They haven't reached the top yet, but you can follow their saga here.

The climb up El Capitan involves about 3,000 vertical feet (914 meters). I was in Yosemite yesterday, and we reached the meadow below El Cap about sunset. Most of the spectators had already wandered off, and we wondered if we could see the climbers. It didn't take too long to find them, but needless to say, they were dwarfed by the cliff. I'm doing these pictures backwards if I'm trying to show how small they are against the cliff, but with a purpose. I realized the climbers had a slightly different story to tell, but probably not one they were intending.

In the original story told by the first people about the cliff, two bear cubs were stuck on top of the cliff and none of the animals were able to rescue them until an inchworm volunteered to climb the vertical face. It was ultimately successful, although the effort took weeks.

Geologists tell stories of the origin of the Sierra Nevada as well. Their stories are based on a different way of understanding things, and their stories are informed by data and observations, both from the Sierra Nevada, and around the world. It occurred to me that the sheer cliff of El Capitan is a metaphor that we can use to understand the immensity of geologic time.

There is nothing quite like seeing the climbers sink into insignificance against the vast expanse of vertical granite. If we imagine each foot of the rock face to represent one million years, the entire cliff face represents 3 billion years. That represents about two-thirds of the entire existence of planet Earth. So we start climbing the face as the inchworm did. There was a lot going on around the world at that time. The first kinds of life had come into existence (primitive microbes), and the first continents were starting to form from the coalescence of numerous volcanic islands. The concentration of oxygen in the atmosphere was starting to rise, albeit very slowly. But there was no vestige of the Sierra Nevada. No rocks of that age exist in California, and for that matter in pretty much the entire American West.

So we start climbing the cliff, each foot representing the passage of a million years. The oldest rocks in California, found in Death Valley and the Transverse Ranges, are 1.7 billion years old. We would find them 1,300 feet up the cliff, perhaps very close to where the climber's base camp dangles. The oldest rocks of the Sierra Nevada found in any abundance are around 500-600 million years old, meaning we would find them at the 2,400-2,500 feet above the valley floor. Keep in mind, every foot is one million years.

The oldest Sierra rocks were formed in an oceanic setting, and were pushed into the edge of the North American continent at different times between 400 and 200 million years. We've reached 2,600-2,800 feet up the cliff as we climb towards the present day. And we haven't even talked about the most common rock in the Sierra Nevada, the granitic intrusions. They happened when oceanic crust was being subducted underneath the continent. As the downward slipping slab of crust warmed up, water was liberated, changing the melting point of rocks at the base of the continental crust. The plumes of molten rock rose from the depths to within several miles of the Earth's surface. There it cooled slowly, forming the crystalline granitic rock. These events took place in episodes extending from 145 to 85 million years ago. In other words, we are now a mere 85 feet from the summit of the 3,000 foot cliff.

From 85 million to maybe 45 million years ago, miles of rock were eroded, exposing the granite at the surface. The mountain range we now call the Sierra Nevada did not yet exist in a way we would recognize. Instead, large rivers with a source in Nevada or farther out flowed westward into a sea where the Great Valley exists today. There may have been highlands, a debate continues. What we do know is that the mountains were most certainly close to their present day elevation by 2 million years ago. That is, two feet from the top of the cliff. At this time, the climate of the planet cooled, and a series of ice ages commenced. Time after time the ice advanced, melted back, advanced, and melt back yet again. This happened a dozen times or more.

About 750,000 years ago a titanic explosion rocked the Mammoth Lakes area. The eruption of the Long Valley Caldera put 150 cubic miles of ash into the atmosphere, covering the American West as far east as Kansas and Nebraska. A vast hole, twenty miles across, ten miles wide, and two miles deep, was left behind. This happened one inch from the summit on our imaginary journey. The last advance of the ice ages receded around 12,000 years ago (about a tenth of an inch from the summit). It was about this time that we have the first well-documented arrival of humans in North America. A tenth of an inch. Everything else, cultural development, wars and invasions, growth of mega-cities, all of it, happened in the infinitesimally small amount of space of the last hundredth of an inch from the summit.

I can't really say that this is the handiest or clearest way of illustrating the immensity of geologic time, but it's what occurred to me as I stared at the climbers inching their way up the cliff, much as the inchworm did many years earlier as it sought to save the bear cubs in the depths of time. The Earth has been here for a long time, and we have not. It's amazing how many changes we have caused in our brief time on this planet.

Postscript: And they've done it! The first ever free climb of the Dawn Wall ( http://www.vox.com/2015/1/14/7545571/el-capitan-climb)

A Series of Fortunate Events: Is it Time to Rename Half Dome?

We spent three days exploring the geology of the Yosemite region last week, and the first stop on Saturday was Washburn Point, an amazingly quiet viewpoint given its proximity to Glacier Point. It's a parking lot, sure, but no bathrooms, no curio or snack shops, few interpretive signs, and in my experience it is far less crowded. One can't see as much of Yosemite Valley from the point as one can from Glacier, but it provides an outstanding vista of the high peaks above the valley floor. And it provides an educational peek at Half Dome. And like no other point in the valley, it reveals the lie in the dome's name. It's not a "half". At best, one could call it Three-quarters Dome, or Four-fifths Dome, but not Half Dome.

We bloggers have our favorite posts, and one of mine is the one I wrote last year as part of my "If These Cliffs Could Talk" series: Tis-sa-ack and Tu-tok-a-nu-la (A Geologic Love Story). You can click on the title to read it if you missed it originally. In the story we find that the dome is named "Tis-sa'-ack" after a beautiful stranger who disappeared after spurning the love of a chief. The chief's actions led to disaster for his people, but eventually the gods relented and the people of the valley once again had plenty

I stuck the statement way at the end of that post, but I wondered at the time why we haven't renamed Half Dome? "Tis-sa'-ack" evokes great beauty and grandeur, and recalls the culture of the original inhabitants of the valley. What does "Half Dome" evoke?

What do you think? Our nation's highest mountain now carries the original name of Denali, instead of the name of an obscure American president who never even visited Alaska. Why can't we consider the same for one of the most famous icons of one of our most beautiful national parks?