A recent comment posted to this blog series conceded that there is more to Saline Valley than meets the eye. Truly Saline Valley is a grand place of epic proportions that often focuses our time and attention on the warm springs therein at the expense of the expanse. When I first arrived in 1980 it was with the full intent of exploring the geology in search of quartz crystals (what else would one expect from a long-hair in a 1960 VW microbus?). I did not know of the springs at the time of my arrival and having discovered the community in that hidden corner of the valley, it was two years before I got around to pursuing my original objective.
Having had the opportunity of several decades of relationship with the Saline Valley, and the privilege of living in the valley for about seven years (summer and winter) I was able to explore and study this rather unique piece of geography and became acquainted with its unique geology. My friend and mentor, Ross Ellis, brought me my first book on geology, which I believe I read cover to cover repeatedly over the course of a quiet summer. This turned out to be a pivotal point in my life and led me to a career in teaching Earth science, for which Ross was always apologetic. (That I should give up a perfectly contented lifestyle at the springs to teach secondary school, he being a college professor himself.)
The purpose of this chapter of the Saline Valley Chronicles is to shed a little more light on an already very bright place. I will endeavor to point out some of Saline Valley’s rather unique attributes.
- Saline Valley is indeed not a valley. A valley has an entry point and an exit point that a river might flow through. Saline Valley is actually a basin, which geologists properly refer to as a bolson.
- Saline Valley is the deepest basin in the United States. With a base elevation of 1000 feet, if one filled the “valley” with water, it would form a lake approximately 5000 feet deep before it drained through the south pass.
- Saline Valley is the only “valley” not penetrated by ground radar. (Visitors are often entertained or annoyed by the antics of navy jet jockeys who like to play “off the radar.” One summer day as I was soaking in the cool lower pool (prior to crystals in the pool) a Navy helicopter landed in the ballfield. The temperature must have been about 115-degrees in the shade. Men in flight suits came over to the shade of the springs and asked if I had seen an A-4 flying around? “No, have you lost one?” Indeed, they had. They found it later that day. It had crashed a few miles from Willow Creek. My friend Turtle Jim was napping at Willow Creek at the time and slept right through it.)
- The Inyo Mountains forming the western boundary of Saline Valley have the steepest relief of any mountain range in the United States, to the best of my understanding. From the valley floor the range rises 10,000 feet in a lateral run of approximately 5.5 miles. That is a gradient of approximately 34.5%. (Ross pointed out a curiosity to me. If one looks at the size of the canyons such as McElvoy and Keynot, for the amount of material that has been washed down out of these maws, the alluvial fans below them are surprisingly small. This may suggest a very deep basin. I may have read that geophysical surveys have put the valley “fill” at around 10,000 feet in depth.)
- Saline Valley is composed in large measure of Paleozoic (age of fishes) marine sediment (sedimentary rock formed at the bottom of an ocean floor by accumulating debris). In the Dry Mountain quadrangle 19,000 feet of this sedimentary rock has accumulated (Burchfiel, 1969), and I believe it thickens further to the west before being terminated by the Papoose Flat Pluton and other batholith structures of the Sierra Nevada and Inyo complex. (Plutons and batholiths are large exposures of igneous rock formed from magma). Most of this thickness is laying on its side or overturned in places. It is my understanding this is the thickest sequence of Paleozoic marine sediment in the western United States. (More on this in the geological tidbits at the end of this article).
- The north pass of Saline Valley hosts a significantly important geologic feature. There are trilobite fossil beds in the Saline Valley Formation (shale member) that mark the earliest recorded boundary between the Pre-Cambrian and Paleozoic geologic eras (approximately 550 million years ago). C.D. Walcott (third director of the USGS after John Wesley Powell) used this location, which is properly known as a “type locality” to define the earliest of the Cambrian period, which he called the “Waucoban age.”
- Saline Valley is a western member of the Basin and Range geomorphic province, normally characterized by “pull-apart basins” which trend NW-SE. Saline Valley is a double pull-apart, with a NW-SE component along the face of the Inyo Mountains, and a secondary pull-apart trending obliquely in the direction of Steele Pass.
- Saline Valley hosted an ambitious mining project in the early part of the 20th century harvesting salt from the lakebed and transporting the salt to the Owens Valley across the Inyo Mountains. It was the steepest tramway in the United States, rising from 1100 feet in the Saline Valley floor to 8500 feet at the crest of the Inyo Mountains, then dropping to 3600 feet at Swansea in Owens Valley. (more information at: http://www.owensvalleyhistory.com/saline_tramway1/page50a.html )
- A large portion of the valley is comprised of marine (sea-floor) sediment. Certainly, the entire area that is now the valley was under seawater. Much of that sediment has been eroded away. The tectonic regime in the Paleozoic era was one of a subsiding continental margin that continued to subside to the west from mid-Utah (known as the Wasatch Line) after the rifting (separation) of then proto-North America. (Geologists refer to this type of subsiding margin as a miogeocline.) Saline Valley marks the thickest remains of this sequence of Paleozoic marine sediments.
- Later, as the Pacific tectonic plate subducted under the North American plate, these marine sediments were compressed and tilted. Much of this deformation can be seen easily, such as the Bonanza King Formation (dolomite) tilted behind Palm Springs, or the Saline Valley Formation or Mule Springs Limestone that are almost standing on end up Waucoba way. Some units in that area have been completely overturned.
- At the same time this subduction was occurring, magma chambers of molten rock were feeding volcanic island arcs off proto-North America. The island arcs are long since gone, but the evidence of the magma chambers remain. The chambers began to cool and crystallize around 160 million years ago (plus or minus 10 m.y.) and formed rock that would eventually become the Inyo Mountains, as well as Hunter Mountain and the Sierra Nevada. These rocks cooled at a depth of about 10 km below the Earth’s surface, according to petrographic analysis.
- Around 30 million years ago the North American plate ran over the Pacific plate’s spreading center, giving rise to a dramatic change in tectonic regime. Previously, the North American plate and the east Pacific plate were travelling in somewhat opposite directions resulting in compression. Now the North American plate is hooked onto the western Pacific plate and travelling in a somewhat similar direction, except that the Pacific plate is travelling about twice as fast as the North American plate, resulting in a lot of tension and extension. The Basin and Range province looks like a lot of stretch marks on a shaded relief map, and that is exactly what they are. Western North America began stretching out. In California, this extension began in some places around 20 million years ago.
- What does this mean to Saline? The rocks of the Inyo Mountains are roughly 150 m.y. old (Triassic period of the Mesozic era … age of dinosaurs), but the range is rather young. Extensionql tectonics created normal faulting which led to the uplift of the buried magma chambers in the late Cenozic era, probably in the late Miocene epoch … age of mammals; let’s call it 5 m.y.: The Inyos are born and Saline Valley becomes a basin.
- How about those volcanics? The cinder cones and basalt (lava) flows that surround the warm springs are dated as young rocks, roughly 3.8 – 2.8 million years young (Burchfiel, et.al., 1987) and the secondary basin that leads to Steele Pass opened up after those volcanics appeared. They likely appeared as a result of the thinning crust resulting from the tectonic extension which stretched things out.
- Finally, what’s with all that white stuff in the area of the springs? Calcium carbonate that precipitated from the evaporation of the warm artesian spring water which we presently enjoy. The extent and expanse of these spring deposits suggests a higher flow volume in the past, most likely during the Pleistocene, when the last Ice Age was melting back (glaciers have been receding a long-time folks) and times were wetter.
Stay tuned for an upcoming chapter in the Saline Valley Chronicles: A geochemical analysis of the waters of Saline Valley. I can tell you what’s in it and where it came from.
|Please consider visiting the home page: Saline Valley Chronicles for a complete list of chapters published to date, and an overview of the project.|
|As you read these humble efforts to transcribe some heritage and history, if you find you have some correction, clarification, or tidbit to add, I encourage you to add a comment at the end of this blog. Contributions will be welcome toward the final project, and all due credit will be given.|
Saline Valley first inspired me to pursue a more serious engagement with the art of photography. My favorite picks are shared on my Smug Mug Gallery of Saline Valley Art at: https://timenspace.smugmug.com/Saline-Valley-Art/
Saline Chronicles directory and overview: https://timenspace.net/saline-valley-chronicles/