|Introduction||Text: The Field Trip||Images: On-Site||Images: Fossils|
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|Click on the image for a larger picture. A seeker of vertebrate paleontological adventure in California's Coso Range explores badlands topography carved in the appropriately named Pliocene Coso Formation, which here yields several species of mineralized mammalian remains some 4.8 to 3.0 million years old--inluding teeth and post cranial skeletal elements of the Hagerman Horse, considered one of the earliest members of the genus of Equus, which incudes all modern horses and equids. Original photograph snapped with a Minolta 35mm camera; this image was created by photographing that original picture with a Nikon CoolPix 995 digital camera.|
Visit the Coso Range Wilderness in Inyo County, California, west of Death Valley National Park at the southern end of California's Owens Valley, where vertebrate fossils some 4.8 to 3.0 million years old can be observed in the Pliocene-age Coso Formation: It's a paleontologically significant place that yields many species of mammals, including the remains of Equus simplicidens, the Hagerman Horse, named for its spectacular occurrences at Hagerman Fossil Beds National Monument in Idaho; Equus simplicidens is considered one the earliest known members of the genus Equus, which includes the modern horse and all other equids.
Please note that fossil collecting is not allowed within the designated Coso Range Wilderness, except by special permit issued by the Bureau of Land Management--a permit given only to individuals who matriculated from an accredited university with a minimum B.S. degree, or represent a museum whose credentials meet the necessary standards of excellence.
And now for the obligatory words of caution. Endemic to the Mojave Desert of California, including the Las Vegas, Nevada, region by the way, is Valley Fever. This is a potentially serious illness called, scientifically, Coccidioidomycosis, or "coccy" for short; it's caused by the inhalation of an infectious airborne fungus whose spores lie dormant in the uncultivated, harsh alkaline soils of the Mojave Desert. The Coso Mountains lie near the northern known edges of Valley Fever prevalence within the Mojave Desert province. When an unsuspecting and susceptible individual breaths the spores into his or her lungs, the fungus springs to life, as it prefers the moist, dark recesses of the human lungs (cats, dogs, rodents and even snakes, among other vertebrates, are also susceptible to "coccy") to multiply and be happy. Most cases of active Valley Fever resemble a minor touch of the flu, though the majority of those exposed show absolutely no symptoms of any kind of illness; it is important to note, of course, that in rather rare instances Valley Fever can progress to a severe and serious infection, causing high fever, chills, unending fatigue, rapid weight loss, inflammation of the joints, meningitis, pneumonia and even death. Every fossil enthusiast who chooses to visit the Mojave Desert must be fully aware of the risks involved.
An inviting route to Death Valley National Park is State Highway 190 out of Olancha in California's southern Owens Valley. Not only is this a much-scenic and reliably accessible pathway to one of the world's favorite haunts, but it also places visitors within convenient striking distance of a most fascinating vertebrate fossil locality in the federally established and administered Coso Range Wilderness--an area no longer accessible to motor vehicles, of course, though it's still wide open for inspection by foot and other non-mechanized means.
Perhaps not a few folks remain unfamiliar with this particular area, and I can surely see why. You just can't spot the bone-bearing beds from the asphalt and, besides, it's more than probable that many a traveler has their eyes fixed on the ever-looming and impressive hulk of the Panamint Mountains up ahead--the range which guards the western side of Death Valley, proper.
The Cosos are that at first blush nondescript piece of territory off to the east and southeast as you speed along the southern fringes of Owens Lake between Highway 395 and the intersection with State 136 to Keeler. They are primarily of igneous origin, born of fire and brimstone, the savage spewings of explosive Cenozoic Era molten lavas in combination with Mesozoic Era batholithic instrusive granites--as unlikely a source of fossil specimens as one could be excused for believing. Yet, tucked way back in the rugged Coso recesses lie the eroding badlands of an ancient lake system which yields up many fossil bones.
The vertebrate remains that await discovery in the Coso Mountains come from the appropriately named Coso Formation, which is upper Miocene to upper Pliocene in geologic age, dated with considerable radiometric confidence at 6.0 to 3.0 years old. And all fossil specimens described from the Coso Formation derive from a restricted sequence some 4.8 to 3.0 million years old. This means that statigraphically speaking the Coso mineralized skeletal material falls within the range of what vertebrate paleontologists call the Blancan Stage of North American Land Mammal Age chronology--that is to say, a geologic interval roughly 4.75 to 1.80 million years ago. Indeed, the Pliocene Coso Formation yields up one of the premiere Blancan Stage mammal localities in all the US West.
Petrological analysis demonstrates that the Coso hydrologic-volcanic system deposited a composite aggregate of roughly 500 feet of arkosic sandstones, shales, claystones, diatomite (a variety of rock composed almost entirely of diatoms, a photosynthesizing microscopic single celled algae), air fall volcanic ash, and basalts in a relatively localized lacustrine (lake) basin influenced by subordinate fluviatile (stream) and alluvial conditions that contributed substantial detrital constituents to the continuously operating three million-year regime of sedimentary-igneous accumulations--all subjected on occasion to geophysically stressful extensional (pulling apart of a portion of the earth's crust) and block-faulting forces.
Significantly, near the conclusion of its depositional history--between four and three million years ago--the Coso Formation starts to record a dramatic influx of clastic-detrital debris now eroding with sudden onslaught from a fault-controlled uplift and eastward rotational tilting of the eastern front of the central to southern Sierra Nevada--a still-active and fully on-going creative geologic process that continues to fashion the great elevations and breathtaking contrasts in topographic relief so spectacularly characteristic of the eastern face of the Sierra Nevada; the northern Sierra of course has stood at approximately the same height as present since at least the early middle Eocene Epoch some 48 million years ago, while the central to southern Sierran area has been substantially uplifted during the past five million years.
Geologist J. R. Schultz was the first scientist to investigate this fossil fauna. He led experienced field technicians from the California Institute of Technology on two extensive expeditions to the Cosos, the first in the winter of 1930-'31, then another during the summer of 1936. Schultz eventually published his geological and paleontological findings in: Schultz, J. R., 1937, A late Cenozoic vertebrate fauna from the Coso Mountains, Inyo County, California, Carnegie Institute of Washington Publication 487, pages 75-109. Among his many fossil mammal descriptions were meadow mice, rabbits, haenoid dogs, very large grazing horses--one of which was eventually recognized by paleontologists as the world-famous Hagerman Horse (one of the oldest members of the genus Equus, which includes all modern horses and other equids)--peccaries, slender camelids, and a short-jawed mastodon. Additional Coso Formation fossil material, secured by teams of professional paleontology explorers who succeeded Schultz's ground-breaking investigations, includes undescribed ostracods (a minute bivalved crustacean), algal bodies (stromatolitic developments created by species of blue-green algae), diatoms (a microscopic single-celled photosynthesizing single-celled algae), fish, a vole (the famous Cosomys primus, named in honor of its occurrence in the Coso Mountains), a large-headed llama, a bear--and, prolific quantities of pollen, palynological specimens that add invaluable paleobotanical information to the Coso story.
The Pliocene Coso Formation pollens come from what paleobotanists call the Haiwee Florule, situated near the shores of Haiwee Reservoir approximately five miles south of the Coso Range vertebrate fossil locality. They were recovered from brownish siltstones in the lower portions of the Coso Formation by the late paleobotanist Daniel I. Axelrod and W. S. Ting through sophisticated--and extraordinarily dangerous--laboratory procedures, involving the use of perhaps the most potent/unforgiving acid known to exist, hydrofluoric acid, whose efficient destructive activity on human tissue is so rapid and overwhelming that permanent damage to epidermis, muscles, and nerves occurs before one even feels any degree of discomfort or pain after skin exposure. Published documentation of that palynological study can be found in the scientific paper, Late Pliocene Floras East of the Sierra Nevada, by D. I. Axelrod and W. S. Ting, University of California Publications in Geological Sciences volume 39, number 1, issued November 7. 1960.
The extensive fossil flora that Axelrod and Ting collaboratively examined from the Pliocene Coso Formation includes such conifers as: Incense Cedar; White Fir; Grand Fir; California Red Fir; Bristlecone Pine; Jeffrey Pine; Sugar Pine; Singleleaf Pinyon Pine; Western White Pine; Lodgepole Pine; Ponderosa Pine; Douglas-Fir; Western Hemlock; and Giant Sequoia--in addition to the following angiosperms: White Alder; Water Birch; Hazelnut; Blue Elderberry; Pacific Dogwood; California Black Oak; Interior Live Oak; Silk Tassel Bush; Black Walnut; Bush Poppy; Snow Bush; Deer Brush; June Berry; Rock Siraea; Thimbleberry; Coyote Willow; Pacific Willow; White Squaw Current; Red Prickly Currant; Kellog Sierran Currant; Sierra Gooseberry; California Slippery Elm; and Zelkova.
Axelrod and Ting concluded that the overall paleo-environmental aspect of the Coso Formation Haiwee Flora most closely resembles today's Sierran pine-fir forests along the moist western slopes of California's Sierra Nevada. Based on the known annual precipitation totals necessary to sustain modern examples of such luxuriant forest vegetation found in the fossil flora, Coso Pliocene times experienced an estimated minimum of 35 inches of rain per year--whereas today the area lies within what geographers categorize as the Mojave Desert-Great Basin transition zone, which in the vicinity of the Coso fossil occurrences receives a scant three to five inches of rain per year, with soaring summer temperatures that frequently exceed 110 degrees Fahrenheit; in forested Sierran regions where modern-day members of the fossil flora now grow, temperature rarely exceed 85 degrees F.
While fossil pollens lie preserved in older horizons of the Coso Formation, all the vertebrate remains occur within a rather narrow zone in the upper part of the Coso sedimentary deposits; they are found in a buff-colored arkosic (composed primarily of the mineral feldspar) sandstone which weathers into subangular chunks. Often, the mineralized mammalian material can be found already weathered out of the sandstone and in the softer claystone a few feet below the sandstone. The fossil-bearing horizon shows up within most of Pliocene exposures of the Coso Formation, so there is a lot of territory to explore. Schultz's original bone localities lie about two and a half miles from State Route 190; reaching them now involves strenuous hiking through rugged, desolate desert terrain. "In the old days," though, one could negotiate a four-wheel drive vehicle up a system of packed sand desert washes, through magnificent outcrops of the bone-bearing Coso Formation, to within a quarter mile or so of the Schultz fossil quarry. As a matter of fact, with the aid of "trusty" CJ5 and CJ7 jeeps, I managed to thread my way back to the familiar box canyon parking spot several memorable times before the Coso Range became a protected wilderness region--a federally mandated designation which means, naturally, that without a special BLM permit you can't keep anything you find there (paleontological, or otherwise)--except in a camera.
Although many Coso bones observed in surface exposures will be fragmental, that doesn't necessary indicate that what you've found can't be identified, eventually. In addition to occasionally encountering isolated-scattered occurrences of complete teeth and associated jaws, watch out, too, for such ostensibly insignificant specimens as fractured limb sections and other assorted incomplete post cranial skeletal elements that reveal a crucially preserved articulating surface (a ball or socket joint, for example). These are prize finds, indeed, paleontologically speaking, as experts in vertebrate paleontology should be able to determine exactly what kind of animal they came from. There are certainly a good many fossil bones waiting to be found and subsequently photographed where they reside in situ in their sandy to clay-rich sedimentary environment. Probably the most efficiently productive method is to locate the fossil-bearing bed (it will tilt with the moderate dip of the sedimentary rocks, and often it occurs on a precipitous hill-slope--so be careful), then hike it out for as long as it is traceable. Some extensions of the bone horizon are quite prolific, while others seem pretty much barren.
All the way around, this is a great area in which to get some exercise.
Though not necessarily during summer times, one must observe with at least a modicum of sagacious deference to the months of June through September in this part of the Northern Hemisphere, when daytime temperatures regularly exceed 105 degrees. More comfortable--and physically safer--hiking weather in this geographical transition zone between the northwestern Mojave Desert and westernmost Great Basin is traditionally encountered during mid to late Fall and mid Spring.
Still and all--speaking of good old hot summertimes--I must admit that my first acquaintance with the Coso bones was during a particularly ultra-thermal early July. This was a number of years ago, when I resided in coastal southern California. This was a number of years ago, before the Coso Range became off limits to off-road vehicles. This was a number of years ago, before the Coso Range became the Coso Wilderness.
The preliminary circumstances: My father and I wanted to escape the dismal, fog-bound coast of Santa Barbara. We wanted to get out into the desert in the worst way possible. Thus, we turned deaf ears to weather reports of 100-plus degrees on the Mojave Desert.
Because when Coso paleo-urges strike...well, there's no turning back.
At the crossroads in Olancha, at a filling station, somebody was talking about 108 in the shade. That somebody was assessing the conservative side of the situation. I was inhaling fire, it seemed. Somebody else, the service attendant, would only shake his head when I pointed, with what could have easily been interpreted as braggadocious indifference to the brutal elements and the imminent dangers they could present, down the road in the direction of Death Valley in reply to his inquiry as to our destination.
At what our maps indicated was the correct intersection of State Route 190 with a dry wash a number of miles beyond Olancha, I idled the CJ5 jeep. No matter that the heat from the engine overpowered the stifling furnace of the Mojave. We re-checked our maps; and then decided to take yet another look at them. This was the place all right, and the wash leading off into the Coso Mountains invited us onward; not to mention the obvious that the potential bone bonanza up ahead was a prime motivator. I got the jeep down in the middle of the wash with the four-wheel drive already engaged, primed for any kind of sandiness we might encounter.
We should have been so lucky as to get stuck in some mere sand.
What happened--and that within sight of the bone-bearing badlands we had traveled some 250 miles to explore--was somewhat more than we had expected. Smoke on a sudden came billowing from beneath the hood, and the nauseating pungence of electrical wires on fire became intense; this, just before the jeep jerked to a halt, cold. We leaped to the situation with canteens in hand, flipping open the hood to already charred remains of wires--and we doused what we could. Then I ran with hectic unsteadiness back to the rear of the jeep where we kept our extra water supply. The five gallon container felt like a bag full of air as I plunged its contents to the flames, dousing them repeatedly until only sickening smoldering remained.
So what did we do next? Consternate? Curse? Nope, we took a hike (fossil mania has its prerogatives). Just up ahead a few hundred feet began the badlands exposures of the Coso Formation. And it was with not a little anticipation that we struck out to them with our remaining full canteens, leaving behind for the moment that dead-in-the sand jeep. We crisscrossed those ancient rocks while following the bone-bearing bed, and the paleontological zeal propelled us further in that glaring, brutal heat than I could have possibly foreseen.
But broken down jeeps wait for every man. A sobering mechanical analysis of the predicament proved that the wiring had been fried to a crisp when the horn mechanism had jarred loose, shorting out the system: too many bumpy roads too many times taken. Aided and abetted by the recollection of some basic electrical knowledge garnered from a recent workshop (studying diagrams and such from the jeep's manual from the curbside at home), we figured pretty quickly that we could safely bypass the obvious tactic of securing assistance when stuck out in the boondocks all alone, where nobody in the world who knows where you are is there to lend a hand--in other words, yelling and yelling like crazy at the top of your lungs. No, this was too easy.
We chose to resort to a plan of action which in theory we had only heard about; this entailed an electrical trick usually quite controversial, but one worth trying under the circumstances. It was decided that if we were ever to get out of that wash alive we would have to "hot wire" the contraption.
The prospects did not excite us much. What if an officer of the law should wander by and catch us in the hot wiring act? Perish the thought! Yet, we persisted and pursued and made it back to tell the tale.
And the moral of this story? Don't toot your horn too often about how you can brave the desert elements, I suppose.
We maneuvered the jeep back to Santa Barbara the same way it got to the Cosos to begin with--towed behind an Open Road camper/RV, and later on down the line (with some creative electrical finagling) we finally got a brand new wiring harness installed, and the four wheel drive "contraption" was by all indications good as new, and good to go: A new-and-improved jeep that actually managed to survive numerous additional deep desert backroad adventures.
To all who visit the Coso badlands, don't be surprised if someday you happen to spot a four-wheel drive vehicle stranded along State Route 190, hood raised, the driver nowhere to be seen. If this is the case, simply follow the boot prints in the sand up a dry desert wash into the Cosos until you come upon a fossil hunter, nose bent to the ground, examining a 4.8 to 3.0 million year-old mammal bone.
|Click on the image for a larger picture. A Google Earth street car perspective (snapped in October, 2011) that I edited and processed through photoshop. The view is practically due east along California State Route 190, headed toward Death Valley National Park, at SR 190's junction with Highway 395 in Olancha, California. Famous venerable landmark cottonwood trees at left. And the northern end of the Coso Range lies dead straight ahead on the skyline. That's where the upper Miocene to upper Pliocene Coso Formation produces several species of 4.8 to 3.0 million year-old mineralized mammal bones in the Coso Range Wilderness, including--meadow mice, rabbits, haenoid dogs, very large grazing horses--one of which was eventually recognized by paleontologists as the world-famous Hagerman Horse (one of the oldest members of the genus Equus, which includes all modern horses and other equids)--peccaries, slender camelids, and a short-jawed mastodon, a vole (famous Cosomys primus, named in honor of its occurrence in the Coso Mountains, a large-headed llama, and a bear.|
|Click on the image for a larger picture. A Google Earth street car perspective (snapped in January, 2009) that I edited and processed through photoshop. Here is the famed packed sand wash that leads to the fossil bone-bearing beds in the northern Coso Range (on the skyline). View is southeastward. The upper Miocene to upper Pliocene Coso Formation exposed in badlands fashion within the Coso Range Wilderness produces several species of 4.8 to 3.0 million year-old mineralized mammal bones, including--meadow mice, rabbits, haenoid dogs, very large grazing horses--one of which was eventually recognized by paleontologists as the world-famous Hagerman Horse (one of the oldest members of the genus Equus, which includes all modern horses and other equids)--peccaries, slender camelids, a short-jawed mastodon, a vole (famous Cosomys primus, named in honor of its occurrence in the Coso Mountains, a large-headed llama, and a bear.|
|Click on the image for a larger picture. Coso explorers stand in one of several packed sand washes that penetrate the Pliocene Coso Formation--an exposure of which lies at middle right of picture. View is a back westward to the eastern flanks of the Sierra Nevada. Please note: This photograph was taken before establishment of the Coso Range Wilderness. Original photograph snapped with a Minolta 35mm camera; this image was created by photographing that original picture with a Nikon CoolPix 995 digital camera.|
|Click on the image for a larger picture. Coso adventurers stand ready to explore exposures of the 6.0 to 3.0 million year-old Pliocene Coso Formation. Here, the Coso produces algal stromatolites (precipitated by blue-green algae), palynological grains (pollens from conifers and angiosperms), and occasional profuse ostracods. View is westward to the eastern slopes of the Sierra Nevada. Original photograph snapped with a Minolta 35mm camera; this image was created by photographing that original picture with a Nikon CoolPix 995 digital camera.|
|Click on the image for a larger picture. Coso enthusiasts relax after hiking through excellent exposures of the bone-bearing Pliocene Coso Formation. The vertebrate remains weather out in the upper part of the Coso Formation, in strata 4.8 to 3.0 million years old. Please note: Photograph taken prior to inclusion of the Coso Formation in the Coso Range Wilderness. Original photograph snapped with a Minolta 35mm camera; this image was created by photographing that original picture with a Nikon CoolPix 995 digital camera.|
|Click on the image for a larger picture. Moody meteorological doings over the Coso Mountains. Pliocene Coso Formation badlands from center to left of image. The vertebrate-bearing horizon is 4.8 to 3.0 million years old. Please note: Photograph taken prior to inclusion of the Coso Formation in the Coso Range Wilderness. Original photograph snapped with a Minolta 35mm camera; this image was created by photographing that original picture with a Nikon CoolPix 995 digital camera.|
|Click on the images for a larger picture. Two different perspectives of the same horse tooth seen in the image directly below (at upper middle). From the 3.5 to 3.0 million year-old section of the Pliocene Coso Formation, Coso Mountains, California. Photographs snapped with a Nikon CoolPix 995 digital camera.|
|Click on the image for a larger picture. Representative mineralized vertebrate fossils observed in Pliocene Coso Formation, Coso Mountains, California. Partial jaw (upper left), teeth, and limb fragments from a horse--between 3.5 and 3.0 million years old. Original photograph snapped with a Minolta 35mm camera; this image was created by photographing that orignal picture with a Nikon CoolPix 995 digital camera.|
|Click on the image for a larger picture. A closer look, with different angle perspective, at the horse jaw fragment in previous image (at upper left). From the Pliocene Coso Formation, Coso Mountains, California--a specimen roughly 3.5 to 3.0 million years old. Photograph snapped with a Nikon CoolPix 995 digital camera.|
|Click on the image for a larger picture. Two views of the same lower jaw from the Hagerman Horse---Equus simplicidens, collected from exposures of the Pliocene Coso Formation, Coso Mountains, Inyo County, California. Equus simplicidens is considered one of the earliest known members of the genus Equus, which includes the modern horse and all other equids. Originally described as Plesippus francescana, but is now recognized as Equus simplicidens. Photograph courtesy a public domain document.|
|Click on the image for a larger picture. Segments of lower jaws from the Hagerman Horse---Equus simplicidens, collected from exposures of the Pliocene Coso Formation, Coso Mountains, Inyo County, California. Equus simplicidens is considered one of the earliest known members of the genus Equus, which includes the modern horse and all other equids. Originally described as Plesippus francescana, but is now recognized as Equus simplicidens. Photograph courtesy a public domain document.|
|Click on the image for a larger picture. Top: horse metatarsal (back foot--the longer specimen at left) and phalanges (foot bones); bottom--horse metacarpal (front foot--the longer specimen at left) and phalanges (foot bones). All from Equus simplicidens, which is considered one of the earliest known members of the genus Equus, a genus that includes the modern horse and all other equids. Originally described as Plesippus francescana, but is now recognized as Equus simplicidens. Photograph courtesy a public domain document.|
|Click on the image for a larger picture. An artist's reconstruction of the Hagerman Horse skeleton--Equus simplicidens, whose mineralized remains occur in the 3.5 to 3.0 million year-old section of Pliocene Coso Formation, Coso Mountains, California. Equus simplicidens is considered one of the earliest known members of the genus Equus, which includes the modern horse and all other equids. Named for its spectacular occurrences at Hagerman Fossil Beds National Monument in Idaho. Photograph courtesy Hagerman Valley Historical Society Museum.|