|Introduction||Text: The Field Trip||Images: On-Site||Images: Fossils|
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Journey to the northwestern sector of Death Valley National Park to visit one of the great Early Cambrian fossil localities in North America--the Waucoba Spring Geologic Section in Death Valley National Park, first studied by legendary Cambrian fossil specialist C. D. Walcott in the late 1890s.
Please note: Fossil collecting is prohibited within the boundaries of Death Valley National Park, except by special permit from the National Park Service--a special use permit given solely to individuals with a minimum B.S. degree from an accredited university who seek to undertake research that can be fully verified and corroborated by the National Park Service. No fossil can be removed from the world-famous Waucoba Spring geologic section in Death Valley National Park without such a permit.
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. And Death Valley National Park just happens to lie within a northern sector of the Mojave where Valley Fever spores have likely been detected. 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.
Relatively few localities on Earth record the important Precambrian-Early Cambrian transition period--a fascinating and truly mysterious interval some 550 to 509 million years ago, when abundant animal life with shells or a hard external covering first appear in the geologic record.
One of the best places to study this crucial boundary between two major geological Eras (Precambrian and Paleozoic) is the Waucoba Spring district some 35 miles southeast of Big Pine, California, on the eastern slopes of the Inyo Mountains, a locality that now lies within the northwestern border of Death Valley National Park (as of 1994, when the Desert Protection Act became law). Here can be found the classic Waucoba Spring geologic section, first measured and described by legendary Cambrian specialist Charles Doolittle Walcott in the 1890s.
Walcott is of course most famous for discovering the Middle Cambrian Burgess Shale fauna of Canada, an extraordinary assemblage of soft-bodied organisms also recognized from a specific Early Cambrian site in China. But Walcott was vitally interested in all aspects of the Cambrian Period, and his detailed analysis of the Waucoba Spring geologic section elevated the site to the status of type reference section for the Waucoban Series of the lowermost Cambrian (542 to 509 million years ago). This means that all age-equivalent strata in the world are correlated with the Waucoba Spring rocks.
Not only is the important Precambrian-Cambrian boundary well exposed near Waucoba Spring, but the sequence is amazingly fossiliferous for strata of such profound antiquity. Among the diverse fossil types that can be observed in situ at Waucoba are archeocyathids, an extinct invertebrate animal that secreted a conical to cup-shaped shell typically one-quarter to two inches long--among the earliest reef-forming animals on Earth, it was likely an early calcareous sponge, although not a few archeocyathid purists still prefer to call it a unique organism with no known modern analogs, deserving of its own scientific Phylum. There are also worm trails, miscellaneous invertebrate tracks and trails (probably from annelids and trilobitic arthropods), salterella (an early experiment, now an extinct member of the Phylum called Agmata, with a small tusk-shaped shell roughly a quarter inch long), algal bodies, brachiopods, and trilobites. Most of the fossil material is surprisingly well-preserved, and there is even one specific site where perfect, intact trilobite carapaces can be observed. Please note of course that the Waucoba Spring geologic section presently resides within the borders of Death Valley National Park. One must not remove fossil specimens within the park's boundaries without formal, written approval from the National Park Service personnel at Furnace Creek in Death Valley.
To reach the Waucoba Spring geologic section, first travel to the intersection of Highway 395 and State Route 168 in Big Pine, Owens Valley, California. Turn east on route 168 and proceed 2.4 miles to Death Valley Road (to Saline Valley, Eureka Valley, and Scotty's Castle). Turn right here.
At the 2.3 mile mark from the SR 168, look to the north of the road (left) and you will begin to see impressive badlands carved in sedimentary rocks deposited in ancient Lake Waucoba--a dominantly detrital sequence of calcareous silts and sands and water-laid volcanic tuffs that accumulated 2.63 to 2.06 million years ago during the Late Pliocene and Early Pleistocene.
In the 1890s, C.D. Walcott, on his way to the Early Cambrian rocks exposed farther southeast, discovered an abundance of freshwater snail fossils from several beds in the Plio-Pleistocene section. For those interested in researching the original reference to the molluscan assemblage, Walcott's paper appears in the Journal of Geology, volume 5, 1897. In 2012, a scientific examination of the Waucoba Lake Beds--their formal geologic name (though some folks prefer "Waucobi Lake Beds")--disclosed numerous species of ostracods (a minute bi-valved crustacean), as well.
When you have driven 13.5 miles from the SR 168, turn right on Waucoba-Saline Road. This path can be followed all the way through Saline Valley, just inside the westernmost boundary of Death Valley National Park. It is for the most part a well-graded dirt road, although the Whippoorwill Canyon area a few miles up ahead tends to be rocky and rutted--a condition one would expect to encounter on a dirt route through such a defile in the mountains.
At the 8.1 mile point from Death Valley Road, Waucoba-Saline Road begins to cut through one of the oldest recognizable sedimentary rock formations in North America: the Wyman Formation. The dark-brown to gray-brown exposures along either side of the path consist of heat and pressure-altered sandstones and siltstones. Some portions of the formation have been changed to quartzite through the eons of tortuous metamorphism. From a distance, these Wyman rocks have a suspicious volcanic aspect: a blocky, basalt-like tone and style of outcropping. Closer examination, though, reveals the obvious sedimentary nature of the material; the strata reveal the characteristic layered bedding and fine-grained composition of altered sandstones and siltstones.
No animal remains have been recovered from the Wyman Formation. At this point in the local stratigraphic section you are standing thousands of feet below the first occurrence of olenellid trilobites, which in a traditional sense used to define the beginning of the Cambrian Period and the Paleozoic Era. Not any longer, though. The Precambrian-Cambrian boundary is now defined as either (1) the appearance of a trace fossil called Treptichnus pedum (feeding trails of a supposed annelid), or (2) a distinctive negative carbon isotope excursion in the sediments at the boundary. Rarely do the two defining occurrences--biological and geochemical--occur together, but there's one place in Death Valley National Park where such a unique combination of defining events can be studied. It's in Boundary Canyon near Daylight Pass, along the road to Beatty, Nevada, in the lower member of the Wood Canyon Formation.
Unicellular organisms and algae most certainly lived here during Wyman time--nearly a billion or so years ago--but due to intense metamorphism any trace of their former existence has long since been obliterated. Still and all, a relatively few pure limestone pods have been reported in the Wyman. If such rocks could be located in the predominantly detrital terrigenous terrain, one would naturally expect a greater opportunity to discover some of the oldest identifiable animal fossils on Earth.
At a point 13.8 miles from Death Valley Road, the path starts to slice through scenic Whippoorwill Canyon. Rocks exposed here belong to the upper Precambrian Reed Dolomite and the Upper Precambrian-Lower Cambrian Deep Spring Formation, roughly 560 to 542 million years old. In contrast to the predominantly detrital Wyman Formation, these two rock units contain relatively high percentages of carbonates, rocks composed of calcium carbonate and magnesium carbonate (dolomite) precipitated on the floors of vast shallow seas.
Near the very top of the Reed Dolomite, in strata transitional with the younger Deep Spring Formation, scientists have found one of the earliest evidences of a widespread variety of animals with shells. Most of the described specimens are minute, measured in millimeters (about one-twenty-fourth of an inch). But they represent such identifiable forms as worm tubes and primitive mollusks. I have personally scoured the Whippoorwill Canyon area for fossils but have yet to find any there. The worm-tube/primitive mollusk horizon occurs in the same formations at Mount Dunfey in neighboring Esmeralda County, Nevada. It also shows up in the Westgard Pass region several miles east of Big Pine. Even so, this is an excellent place for paleontological explorations. It is one of the most significant geologic regions in all the world. Because most of the sedimentary material exposed here is miraculously unaltered, there is great potential for the discovery of the oldest identifiable animal with a shell.
For two miles the Waucoba-Saline Road carves through the Precambrian strata of Whippoorwill Canyon. All along this route you move gradually upsection--that is, as you proceed south the rocks become progressively younger in geologic age. The base, or the section bearing the oldest layers of the classic Waucoban Spring section, as defined by pioneering paleontologist Walcott, occurs in transitional rocks of the Late Precambrian-Lower Cambrian Deep Spring Formation and the overlying lowermost Cambrian Campito Formation. This world-famous change from the Precambrian to the Paleozoic Era lies directly to the east of the Waucoba-Saline Road, 16 miles from the Death Valley Road junction. To the left of the road you will note typically blocky weathering black to brownish quartzites and shales of the Andrews Mountain member of the Campito Formation, within which some of the oldest olenellid trilobites have been recovered. The fossils are by no means common here--they are, indeed, frustratingly rare: one lone occurrence discovered by a very lucky paleontologist, although unfortunate evidence exists to conclude that perhaps that specimen came from much younger strata; the trilobite was recovered from a wash and could have been transported to the site of discovery. Outcrops of the Andrews Mountain member in neighboring Esmeralda County have yielded a few identifiable trilobite specimens.
After examining the exposures of the Campito Formation here, proceed one additional mile to the turnoff to Waucoba Spring, where you will be within a short hiking distance of fossiliferous Early Cambrian strata in the Waucoba Spring geologic section. Waucoba Spring lies approximately one-half mile west of Waucoba-Saline Road, 17 miles south of the intersection with Death Valley Road.
The spring is an old and famous watering hole for the local fauna, including feral burros whose presence in the Death Valley region has generated much controversy. Some investigators claim the burros foul critical watering holes and scare off more sensitive creatures such as bighorn sheep. Others exonerate the asses, pointing out that they have just as much right to exist in the wild as any indigenous creature and charges that they are solely to blame for the ruination of the ecology are absurd.
During my first visit to the Waucoba a number of years ago, I recall having observed quite a few burros. They'd halt right in front of a moving vehicle, staring inscrutably ahead. Subsequent trips to the Waucoban wilds disclosed a dramatic drop in the observable burro population. I do not know whether natural selection has been weeding out the weak or artificial measures have been employed--such as periodic thinning of the paces/herds by gunfire.
Excellent representative exposures of the classic Early Cambrian Waucoba Spring section described by Walcott lie to the east of Waucoba-Saline Valley Road. To reach the fossil-bearing exposures it is necessary to hike approximately a quarter of a mile to the nearest hillslope, directly east of the turnoff to Waucoba Spring. This slope is composed of the greenish shales and quartzites of the Montenegro Member of the Campito Formation, within whose detrital rocks can be seen worm trails, invertebrate tracks (many made by trilobites, but also several types that have not yet been positively identified) and trilobite head shields, or cephalons (complete specimens rather rare). Another region in which to hunt for the oldest reasonably common trilobites in the geologic record is over in neighboring Esmeralda County, Nevada, where several Montenegro Member sections yield many complete Fallotaspis trilobites, along with several other early spectacularly preserved olenellid trilobites.
As you continue to hike in a generally southeasterly direction along the hillside, the greenish shales and quartzites give way to geologically younger gray-blue to buff-brown archaeocyathid-bearing limestones of the Poleta Formation. Most of the extinct calcareous sponges range from a half-inch to two inches in length, and quite a number of archeocyathid fragments have weathered out of the rocks. A few of the more densely packed clusters of archeocyathids observed in the limestones are likely the preserved remains of primitive, localized reefs.
All of the trilobites within the Poleta Formation occur in the younger, gray-green shales which lie directly on top of the archeocyathid-bearing limestone. In addition to the trilobites, perfect specimens of which remain elusively infrequent in the extensive deposits of shale, abundant worm trails and invertebrate tracks can also be seen. These fossiliferous shales are in striking stratigraphic contact with the older archeocyathid limestone, and the lithologic contrast is so distinctive that it can be traced with assurance throughout the Waucoba Spring district and western Great Basin, in general (northern Inyo County and western Esmeralda County, Nevada).
Additional superior fossil material can be observed in place from the next-youngest geologic rock unit in the Waucoban section, the Harkless Formation. Abundant worm trails and invertebrate tracks, salterella (diminutive tube-like, roughly conical shells secreted by an extinct animal of unestablished zoological affinity), and a few species of archeocyathids are characteristic of the formation, which outcrops roughly three-quarters of a mile to one mile directly east of the Waucoba Spring turnoff. The Harkless is chiefly a terrigenous unit of gray shale and siltstone, interbedded with brownish quartzites. Minor lenticular blue-gray limestones in the youngest phases of deposition often yield large archeocyathids, some up to nine inches in length.
Expect to conduct extended periods of hiking in order to examine all of the fossil material present in the Waucoba geologic section directly east of the turnoff to Waucoba Spring. The trilobites in particular are seldom even common at any one locality. They are usually confined to the greenish shales of the Poleta Formation, several feet above the archeocyathid-rich limestones.
A better place in which to observe in situ trilobites lies farther south, in much younger exposures of the Early Cambrian Waucoba Spring geologic section at Algae Ridge, where the Lower Cambrian Mule Spring Limestone contains abundant fossil remains of a species of cyanobacterial blue-green algae called Girvanella.
The Mule Spring limestone contains the highest concentration of fossil algae of any Cambrian formation in the Great Basin. It is estimated that in some horizons Girvanella algal bodies constitute fully 40 percent of the limestones by volume. At Algae Ridge these fossil remains are certainly locally prolific, appearing in the blue-gray rocks as oval to circular black concretionary structures roughly one-quarter to three-quarters of an inch in diameter.
The Mule Spring Limestone marks the very top, or youngest part of the Waucoba Spring geologic reference section. Above it lies the Middle Cambrian Monola Formation whose prominent exposures can be seen about a mile and a half to the south, near where the dramatic expanse of Saline Valley commences.
The prime trilobite locality lies on Algae Ridge in the Saline Valley Formation. Prior to December 1994 this site was open to hobby fossil collecting, lying as it did outside the boundaries of Death Valley National Monument. Please note that it now lies within the borders of Death Valley National Park. Look and touch, but don't keep anything you find there--unless it's a photograph of a fossil specimen, of course.
At the fossil site one can examine abundant trilobite head shields, plus occasional perfect, intact specimens. During my last visit to the site before it was assimilated by the national park system, I was fortunate to find three complete, whole trilobites--a powerfully exhilarating and rewarding experience, to be certain. Perfect specimens were surprisingly common, interestingly enough--a fact that helped set this specific Early Cambrian fossil site apart from most others.
The Waucoba Spring district is a rugged and pristine land. It is also out in the middle of nowhere, miles from civilization. This means that adventurers traveling to the region must make certain that their vehicles are in perfect working condition and carry with them extra food, plenty of water, spare fan belts (and know how to change one!) and protective clothing. In short, take all necessary precautions to ensure a safe experience.
Most of my Waucoba Spring trips were during the early Spring, mainly in early to mid April. I'm not presuming to suggest that this is the most comfortable time of the year there, but by way personal experience I recall one August spell that turned into pure vapor lock of the brain--soaring daytime temperatures even up in Whippoorwill Canyon at elevations over 7,000 feet--and a brief stay in December practically froze my toes off.
The Waucoba district certainly contains one of the greatest Early Cambrian stratigraphic sections in all the world: the classic Waucoba Spring section first described by C.D. Walcott in the late 1800s. Except for development of the graded Waucoba-Saline Road and a few additional minor off-road-vehicle trails, the region likely appears much the same as it did in 1897 when Walcott first passed through. The Precambrian-Early Cambrian transition exposed here records the preserved remains of plants and animals that lived in this part of what is now the Great Basin some 600 to 510 million years ago--a time so distant, so primordial that it echoes back to a moment when the Spirit moved over the face of the waters and said, "Let there be light."
|A visitor to the Waucoba district looks eastward to the classic Early Cambrian Waucoba Spring section in northwestern Death Valley National Park. The slope at upper left is composed of the Lower Cambrian Montenegro Member of the Campito Formation (near the base, or oldest layers of the section), which yields some of the oldest olenellid trilobites in North America, in addition to many annelid burrows and arthropod tracks and trails. Prior to December 1994, when the Desert Protection act became law and created Death Valley National Park, the world-famous Waucoba Spring geologic section could be found outside of Death Valley National Monument. Today, the Waucoba Spring district lies within Death Valley National Park. Removing fossils from a national park without formal written permission from the National Park Service is verboten.|
|Looking east from one of the fabulous trilobite localities in the Waucoba Spring Geologic Section, Inyo County, California--a site now included in Death Valley National Park (prior to 1994 it was outside Death Valley National Monument). Complete, whole extinct arthropods can be recovered here from a seven to ten-foot thick section of fissile, olive-gray shale at the very top of the Lower Cambrian Saline Valley Formation (the brownish material in the lower foreground), just below the contact with the overlying Lower Cambrian Mule Spring Limestone--the massive dark blue carbonate ridge just below center. The Mule Spring yields locally abundant algal nodules called cyanobacterial oncolites, oval to circular bodies embedded in the carbonate matrix precipitated by an extinct species of blue-green algae called Girvanella.|
|A view roughly eastward to a portion of the classic Late Precambrian through Early Cambrian Waucoba Spring geologic section in Death Valley National Park. In the late 1890's, pioneering geologist/paleontologist Charles D. Walcott (the scientist who discovered the Middle Cambrian Burgess Shale fauna of Canada, a world-famous invertebrate assemblage that includes numerous soft-bodied organisms not usually encountered in the geologic record) first measured and described this section--type locality for the Lower Cambrian Waucoban Epoch, 541 to 509 million years ago, oldest subdivision of the Cambrian Period. Archaeocyathid-bearing limestones of the lower Poleta Formation along slopes at left to lower center; recessive interval at right-center includes shales and quartzites in the middle Poleta Formation. Bluish ledge just below brownish slopes at far right is limestone in the upper Poleta Formation. Brownish slopes at right are quartzites and shales in the Lower Cambrian Harkless Formation.|
|Wild (feral) burros in the Waucoba Spring district; the fellow with black fur, white snout and eyes is a little more difficult to spot at right-center of image. Hills in the background are composed of quartzites, shales and limestones of the Lower Cambrian Saline Valley Formation.|
|An essentially complete olenellid trilobite I collected from the Lower Cambrian Saline Valley Formation, Waucoba Spring geologic section, Inyo County, California, before the area was assimilated into Death Valley National Park. Note that the glabella is slighly crushed, unfortunately. Called scientifically Mesonacis fremonti.|
|An almost complete olenellid trilobite from the Lower Cambrian Saline Valley Formation, Waucoba Spring geologic section, Inyo County, California. Only a few spines on the right side of the thorax (facing camera) are missing. Called scientifically Mesonacis fremonti. From a locality that is no longer accessible to unauthorized collectors, lying as it does within the expanded boundaries of Death Valley National Park (since 1994). Photograph courtesy an individual who goes by the cyber-name Trilobite Russ.|
|Branching archaeocyathids--an extinct calcareous sponge--from the lower limestones of the Lower Cambrian Poleta Formation, Waucoba Spring Geologic Section, Inyo County, California. Both specimens collected before the Waucoba Spring paleontological district became part of Death Valley National Park.|
|Annelid (worm) trails on a slab of quartzite (heat and pressure-altered sandstone) from the Lower Cambrian Harkless Formation, Waucoba Spring Geologic Section, Inyo County, California. Specimen collected before the Waucoba Spring paleontological district became part of Death Valley National Park.|
|Algal bodies (the oval to circular, dark nodule-like structures), genus Girvanella, from the Lower Cambrian Mule Spring Limestone, Waucoba Spring Geologic Section, Inyo County, California. The distinctive fossil bodies were precipitated by an extinct species of cyanobacteria, a blue-green algae. Specimens collected before the Waucoba Spring paleontological district became part of Death Valley National Park.|