California Geology: An Aerial Perspective — Part 1 of 2

Among the many hobbies and interests that I have had throughout my life, two specific ones have deeply resonated ever since my childhood. One is the passion for aviation and the other, an innate curiosity to know and decode the landscape around me.

My passion for aviation started with my first airline trip that I can remember from the age of 3 when my family temporarily moved back to India from Zambia. I was fascinated by the gravity defying nature of airplanes, the elegance and grace with which they maneuver and was awed by the pilots that have mastery over them. I became a pilot at the first possible opportunity about 16 years ago and continue to enjoy the privilege and freedom that it has given me to date.

Separately, my curiosity in geology began early on when my family took me on pilgrimage trips to a popular mountain town of Tirumala. Tirumala is nestled in a high valley in the Eastern Ghats of South East India. I was itching to know what the topography of the hills looked like, what was special about that specific valley. I’d force a stop at every possible vista point on the winding road that took us up to the temple.

Little did I know at that time that I myself would become a hobby pilot and that the two separate passions could be connected. Here we are several decades later: I am a California native that has access to the one of the most geologically diverse landscapes in the US, I have a loving and supportive family, I have amazing friends with intersecting interests and passions, and above all I have the freedom and luxury to rent a beautiful plane to go explore!

A Short Disclaimer before I proceed further: I am an amateur geologist. Any description that I provide is based on what I have read and learnt from various sources. My description should provide context but should not be used as a trusted source of information.

Flight and Route Planning:

This trip was planned at very short notice. After a grueling December and January it was time for a fun adventure. My family approved my disappearance for an entire day, my pilot friend -Matthias- was available and willing to come along for the ride, the newest Cessna 182T on my club’s fleet was not already taken, and the weather was spectacular.

There were many options for destinations and routes but the initial motivation for my plan came from an article that I read about the possible closure of the Stovepipe Wells Airport in the Death Valley. Death Valley has been on my bucket list for a while, and it made sense to log a landing at Stovepipe Wells before NPS decides to do away with the airport. This also gave an abundance of opportunity to explore the complex geology of the Eastern Sierra.

California’s diverse landscape and terrain generally springs from the interaction of the North American tectonic plate with the Oceanic plates to the west. My over simplified and basic understanding for the landscape is the following:

1. There used to exist an oceanic plate called the Farallon plate that subducted under North America in this area.
2. This formed a massive volcanic chain where the Sierra currently exists (much like the cascade range with all the wonderful volcanoes in Northern CA, OR and WA).
3. The Farallon plate eventually completely vanished under North America including its mid ocean ridge. This gave rise to the strike-slip San Andreas fault that we see today.
4. The original volcanic range since then eroded away into a small set of hills and the magma under them slowly cooled under them to form massive volumes of granite.
5. As the mid ocean spreading ridge of the Farallon plate also subducted under North America, it continues to stretch the crust of North America apart from underneath causing two things — the uplift of the Sierra Nevada exposing the ancient granite magma under those old volcanoes, and the creation of the Basin and Range province east of the Sierra creating parallel chains of mountains and valleys like the Owen Valley, the Panamint Valley, the Death Valley, etc.

The intent of this trip was to explore as large a swath of this terrain as possible within a day’s flight. I planned to cover the Yosemite area, the Eastern Sierra Escarpment, Western end of the Basin and Range Province, a sneak peek at the Mohave Desert, and the San Andreas Fault zone. Annotated flight tracks below to provide some context for the rest of the narrative. I’ll cover our trip from Palo Alto to the Death Valley in part 1 of this post.

Pre-Lunch (legs 1, 2, 3) — the tougher part of the flight involving a lot of mountain flying during the early part of the day

Leg 1: Palo Alto (KPAO) to Lone Pine (O26)

Leg 1a: KPAO to Tioga Pass annotated

Our bird for the day, preflighted and fueled up, ready to go!

We departed Palo Alto at 7.30am to Lone Pine expecting to get flight following up to Lee Vining. With the smooth and crisp morning air, the only noteworthy events were getting routed around a couple of 737s on approach into Oakland during the climb out. As the flight progressed we were greeted by views of the SF Bay, Central Valley and the Sierra Crest silhouette against the bright morning sky.

Happy and excited!

Left: Mirror surface of Leslie Salts and the salt ponds of the South Bay on the initial climb out Right: Lake Del Valle reservoir near Livermore

Modesto Airport (KMOD) — midway point between Palo Alto and Yosemite, we were at 8,500 ft over most of the Central Valley

Sierra Crest in Ansel Adams Wilderness (we backpacked on the other side in July 2020)

Yosemite Valley & Tioga Pass:

We flew to the south and east of Yosemite Valley due to better lighting and contrast for pictures, but also to survey the areas that Matthias and I backpacked last summer. Please read my previous story for ground level details and our backpacking experience.

The general geologic theme of the Sierra Nevada is beautifully exposed in Yosemite National Park. The granite batholith brought to the surface through uplift has transformed into beautiful granite domes weathered through erosion and glaciation. While these are generally visible from the valley and the roads that cut across the park, the aerial perspective showcases the scale of this geology. Half Dome though majestic in its own right is only one in several granite domes that literally dot the aerial landscape.

The first prominent encounter over Yosemite — the towering El Capitan

Yosemite Valley and Tenaya Canyon looking east — the aerial perspective shows the vast fields of granite domes that dot the Yosemite area including the most prominent of all of them, Half Dome

Little Yosemite Valley “behind” Half Dome with the Merced cutting through (back side of Half Dome: not commonly seen unless hiking up to it or from the air)

Left: Tenaya Canyon and Yosemite Valley looking west, the gently west slope of the Sierra down to the central valley is evident — from this viewpoint, the cable route is really a very short climb from the snow capped eastern shoulder of Half Dome to its summit Center: Clouds Rest divides Tenaya Canyon from Little Yosemite Valley — we summited it on our backpacking trip last summer Right: Full scale of the glacially carved valley — the aerial perspective provides an appreciation for the depth and scale of the valley in contrast to the surrounding plateau

Here on, we left the Yosemite Valley behind and entered the high Sierra region of Tuolumne Meadows and the surrounding peaks. These peaks are rugged granite spires that saw much less of the glacial erosion since they rose well above the glaciers that covered the area. This route across the High Sierra roughly follows the John Muir Trail that we backpacked last summer.

Left: The iced up and snow covered Sunrise Lakes — we spent a night by the lower Sunrise Lake last summer (left most of the 3 lakes) Right: Upper and Lower Cathedral Lakes with Echo Peaks casting its shadow over them — lower Cathedral Lake is a beauty and an easy day hike from Tuolumne Meadows. Clearly seen here, the Lake is a glacial tarn, fills a glacially carved granite bowl, would have been even more evident in the summer with little to now snow.

High Sierra spires poking above the surface of and untouched by the ice age glaciers, all rising over Tuolumne Meadows

Cathedral Peak up close — at 10,500 ft it is again clear that these spires are rugged and not touched by the glaciers that created the domes back in the lower altitude Yosemite Valley region

Tuolumne Meadows — covered with a blanket of pristine snow with the meandering Tuolumne River, and various oxbow lakes clearly visible- rarely does one see a meandering river in the middle of a mountain range. By flight it is clear that the Sierra is less of just a mountain range but really a high plateau that is tilted to the west — very gentle climb from the west with a steep escarpment on the east, which will be evident in the following sections.

Lyell Canyon below with Kuna Crest, Kuna Peak and Blacktop Peak — all above 12,000ft at our eye level as we set ourselves up to cross Tioga Pass. Lyell canyon is a spur that begins at Mt. Lyell and carries the Tuolumne River to Tuolumne Meadows, a good day hiking area to beat the crowds at Tuolumne Meadows

Crossing the Tioga Pass required a fair bit of pilotage and terrain awareness. Definitely a fun task in the smooth conditions that we encountered. This was my first flight as pilot in command (PIC) across the pass, however I have been a passenger/co-pilot a few times with Matthias as PIC. When the winds aloft pick up being tossed around over the pass with high terrain on either side is quite unnerving. The pass is not in a straight orientation, and requires quite a bit of zigzagging with tall walls on either side. The western side of the pass is oriented in a north-south direction while the eastern side is a canyon oriented in an east-west direction. I would strongly recommend that any pilot either practice this route on a simulator, witness the navigation as a passenger or have a “Tioga Pass experienced” pilot as a passenger before attempting to fly over it for the first time. Matthias was of tremendous help here both as a navigator and a photographer, without his help we would have no pictures of this area as I would have had to focus the entirety of my attention on piloting the plane. At this point we also lost communication with ATC due to high surrounding terrain, we were on our own for the most of our flight east of the Sierra.

Left: Mt. Conness to the north (left) of Tioga Pass — An Alpine climber’s paradise. Matthias an ardent climber and mountaineer has summited Mt. Conness several times! Center: Tioga Pass with Tioga Lake nestled in it, the other side of the pass is the canyon formed by Lee Vining creek to the right of Tioga Lake. Right: Mt. Dana, Dana Glacier, Dana Plateau south (right) side of Tioga Pass. Mt. Dana is the northern most 13er in the Sierra. Unlike the granite of Yosemite and Mt. Conness, Mt. Dana and the other peaks in the adjacent Ansel Adams Wilderness comprise volcanic metamorphic rocks. They have a darker and redder appearance.

Mono Lake & the Mono-Inyo Craters:

Leg 1b annotated— Tioga Pass to Lone Pine Airport (O26)

The landscape on the eastern side of the Sierra is in stark contrast to the west. It is amazing to witness several concepts taught in elementary and middle school geography crop up with such high definition. First, given the height and size of the range there is a clear demarkation of the windward and leeward sides of the range. The other side of Tioga Pass is a high desert with desert shrub, endorheic lakes, and barren hills and mountains all in the rain shadow of the Sierra. The effects of the large Basin and Range province is also immediately visible. Parallel chains of mountains and valleys (horsts and grabens) as a result of stretching and thinning of the crust is evident looking beyond Mono Lake. These are a series of rift valleys (not one or two but several spanning the width of the state of Nevada) much like the Great Rift Valley in East Africa that was taught in school.

Crossing over Tioga Pass, a steep drop to Lee Vining on the eastern side of the Sierra, Mono Lake in the background

Several volcanic craters and volcanic fields are scattered throughout the Eastern Sierra and Owens Valley. I believe the origin and cause of these volcanoes (some having erupted recently) is still much debated among the research community.

Mono Lake — its shoreline dotted with salt tufas, town of Lee Vining and Lee Vining Airport

The Mono Craters rugged and craggy chain of volcanic domes and craters extend north through Mono Lake and its north shore. Mammoth mountain and ski area form the southern end of the chain

Obsidian Dome, one of the craters in the chain — our daughter, Reya was so excited to actually find little pieces of Obsidian right by it when we drove there a couple of years ago. In summer from certain angles this dome does shimmer in the sun.

Long Valley Caldera

The long Valley Caldera is a very interesting geologic feature in the Mammoth Lakes area. I read about it after one of our family vacations to Mammoth Lakes. It was formed when a monster volcano erupted and deposited a thin layer of ash throughout the Western US. This layer of ash and cemented debris still exists to the south of the caldera and is called the Bishop Tuff or Bishop Tableland. The Owens River carves a gorge through this tableland before reaching the Owens Valley further south. Given the sheer size of this caldera it is very difficult to perceive it from the ground or the surrounding roads. Even satellite images or terrain view on Google Maps does not quite clearly show the presence of a caldera, however it is so obvious to notice as we flew over it!

The Long Valley Caldera. The caldera walls, floor and the resurgent dome all clearly visible and distinguishable from the above.

Mammoth Yosemite Airport and the town of Mammoth Lakes not shown here are within the Long Valley Caldera

The Owens River Gorge that cuts through Bishop Tuff and Bishop Tableland

Bishop Volcanic Plateau or Bishop Tableland, an area filled with volcanic ash from the Long Valley eruption. White Mountain Range that forms the eastern wall of Owens Valley in the background

Owens Valley

As we flew further south, we entered Owens Valley, which is a rift valley with the White and Inyo Mountains to the east and the Sierra Escarpment to the west. Due to its barrenness the rift valley is clearly distinguishable from both the ground and the air. We were originally planning to land and refuel at Bishop but made a last min decision while on final to go around and refuel at Lone Pine instead in order to enjoy the views of Mt. Whitney from the airport. We were at 7,500 ft for this leg with peaks towering above us to 13,000 ft and 11, 000 ft respectively on either side. We flew past Buttermilk Country and the Big Pine Volcanic Field before touching down at Lone Pine.

Buttermilk country just west of Bishop, the site of old Tungsten mines and several erratic bounders

Bishop Airport

Left: Owens river meandering through Owens Valley near Bishop (looking East at the White Mountain Range), Right: the town of Bishop (looking West at the Sierra Escarpment)

Owens Valley looking south, a classic rift valley where either side rises and the valley drops as Earth’s crust expands and stretches. Lava flows and cinder cones of Big Pine Volcanic Field visible ahead

Big Pine Volcanic Field

the first glimpse of Mt. Whitney from the north at 14,500ft (tallest in the contiguous US)

Alabama Hills- apparently another Sierra in the making — the site of the powerful 1872 Lone Pine earthquake when the entirety of the Alabama Hills were thrust upward by 20ft.

Mt. Whitney and its distinguishable shape from the south as we turn final for Lone Pine

Lining up to land on Rwy 34, beautiful strip with new asphalt that stands out

Long taxi to the fuel pump — Alabama Hills & Grand Sierra Escarpment in the background

The first leg was the longest — a solid 2 hours. Matthias was kind enough to offer to fuel up the plane while I stretched my arms and legs and took in the surrounding scenery. This was our only fuel stop and was more than ample fuel for the remaining 4.5 hours of flying back to Palo Alto. I forgot to mention that it was a day of the bagels sponsored by Matthias. We enjoyed in-flight breakfast bagel sandwiches on the way here, and had a small bagel snack and piping hot chai at Lone Pine.

8MM at Lone Pine with Mt. Whitney towering above

Matthias diligently fueling up :)

Leg 2: Lone Pine to Stovepipe Wells

This next leg was the shortest, climb over two ranges and hop two basins over into the Death Valley. We would have to turn east and cut across the basin and range, with the basins, rift valleys or grabens getting progressively deeper. First range to cross would be the Inyo Range getting out of Owens Vally, the other side of the Inyo Range is the Panamint and Saline Valleys followed by the Panamint Range and then the Death Valley. It was a steep drop to sea level from over 7,500ft into Stovepipe Wells, which required a north detour for descent management before landing at the beautiful Stovepipe Wells airport.

Leg 2: Lone Pine (O26) to Stovepipe Wells (L09) annotated

Owens Lake

The story of Owens Lake is rather sad. Owens Lake is an endorheic lake like most others in the area and was once a lake filled with water fed by the Owens River. There is a whole water wars story behind why Owens Lake is now a dry bed of salt causing toxic air pollution to neighboring settlements. The Owens River is now routed to the city of LA as a water source through the LA aqueduct. Mono lake nearly suffered the same fate but was prevented through the efforts of ecologists.

Owens Lake fills the width of the Owens Valley

Smaller remnants of water scattered around the old lake bed

Leaving Owens Valley and climbing over the Inyo Range — one more look at the Sierra Escarpment

Panamint Valley, Death Valley

Left: Saline Valley (to the north), Center: Death Valley (straight and to the east), Right: Panamint Valley (to the south)

Panamint Dunes up close

Several interesting and colorful rock strata in the Panamint and Inyo Ranges

The three ranges and two valleys crossed so far — the lowest point (Death Valley below us) and the highest point Mt. Whitney (in the distance) in the contiguous US. Both visible in the same view and within 85miles of each other, interesting the disparity tectonic forces can create.

On final for Rwy 5 at Stovepipe Wells

Doing our part, signing the petition to keep the field active

Mesquite Flat Sand Dunes

The runway at Stovepipe wells with buckled asphalt likely exacerbated by the desert climate — it was a pretty rough ride down the runway but perfectly safe and manageable.

Another pre-lunch snack: cheddar cheese bagel and water :)

Overall it was a very satisfying morning and a lot of miles covered. We reached our destination and farthest point from home, super smooth air, nearly zero winds aloft and surprisingly still very fresh!

rest of the trip to be continued in part 2…