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:
- There used to exist an oceanic plate called the Farallon plate that subducted under North America in this area.
- 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).
- 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.
- 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.
- 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.
Leg 1: Palo Alto (KPAO) to Lone Pine (O26)
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.
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.
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.
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.
Mono Lake & the Mono-Inyo Craters:
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.
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.
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!
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.
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.
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.
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.
Panamint Valley, Death Valley
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…