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Visit a remarkable, prolific 518-million-year-old fossil locality situated several miles north of Death Valley National Park in Esmeralda County, Nevada--the Gold Point fossil site, where paleontologists have recovered the single largest assemblage of Early Cambrian trilobites yet described from North America; here's an opportunity to collect at least 12 species of trilobites, abundant salterella (the "ice cream cone-shaped" fossil), archeocyathids (extinct calcareous sponge), brachiopods, algal remains, plus numerous varieties of annelid and arthropod tracks and trails--a truly diverse assemblage of Early Cambrian fossil remains from the famous Harkless Formation. And now for the obligatory words of caution. Endemic to the Mojave Desert of California and southern Nevada (including Las Vegas, 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 the Gold Point fossil site just happens to lie within a northern sector 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 of California and southern Nevada must be fully aware of the risks involved. |
Click on the image for a larger picture. A panorama across the community of Gold Point, Nevada--in the vicinity of which occurs the Gold Point fossil locality in the lower Cambrian Harkless Formation, which yields beaucoup trilobites, archaeocyathids (extinct calcareous sponge), salterella (extinct ice cream cone to tusk-shaped invertebrate animal placed into its own unique phylum, called Agmata), brachiopods, algal remains, and many varieties of annelid and arthropod tracks and trails. A screen shot capture from a video uploaded to YouTube by an individual who goes by the name of R. Holt that I edited and processed through photoshop. |
One of the great Early Cambrian trilobite localities in the western United States can be found in Esmeralda County, Nevada, a number of miles north of Death Valley National Park. It's a ne plus ultra paleontological place where invertebrate paleontologists have identified at least 12 species of trilobites from a series of terrigenous and carbonate strata mapped as the lower Cambrian Harkless Formation, some 518 million years old--a specific fossil locality, as a matter of fact, that has yielded the single largest assemblage of Early Cambrian trilobites yet described from North America. Thus, it is a unique and scientifically invaluable area--still accessible to amateur fossil aficionados, by the way, primarily because the exceptional extinct arthropod fauna has already been described in detail by a noted Cambrian trilobite specialist, who published his findings in a peer-reviewed technical scientific document several years ago. Nevertheless, the wonderful arthropod horizon remains a geologically sensitive place. Visitors to the region must respect its vulnerable existence, understanding that if commercial collecting parties begin to desecrate the stratigraphic integrity of the exposed strata--ripping the fossiliferous rocks from their primordial resting grounds by mechanized or other unauthorized means (for example, removing with hand tools considerable quantities of rock obviously commensurate with illegal collecting operations)--officials with the Bureau of Land Management (BLM) will have no recourse but to close the entire district, preventing interested amateur collectors from experiencing the exhilarating rewards of paleontological discovery here; of course, it is not likely that commercial collectors would favor the Gold Point area, anyway, since complete, perfect trilobite specimens are so rarely recovered--a not unexpected situation when dealing with the majority of Early Cambrian fossil localities world-wide. Needless to report, commercial collectors must stay away; otherwise, only those with certificates of university accreditation will be allowed to keep what they find. The Gold Point locality lies in the vicinity of Gold Point in Esmeralda County, Nevada--several miles from another exceptional paleontologic place--a renowned regional sedimentary protuberance from whose Late Precambrian rocks paleontologists have identified one of the earliest known assemblages of shell-secreting animals on Earth. The specimens occur in dolomitic carbonates transitional between the Precambrian Reed Dolomite and the Deep Springs Formation and apparently represent varieties of primitive worm tubes occasionally observed in correlative deposits in Mexico, Russia, and Namibia. What's particularly intriguing about this Late Precambrian site is that the curious annelid tubes, only a few millimeters long in most instances, apparently occur in rocks approximately a full thousand feet below the first appearance of olenellid trilobites in the local stratigraphic section--extinct arthropods that in a traditional geologic context used to define the base of the Cambrian System--now recognized as roughly 541 million years old, not 570 million years ancient as had been held for most of the 20th Century. 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 Late Precambrian-Early Cambrian Wood Canyon Formation. Another ultra-significant Precambrian-Cambrian transitional stratigraphic section can be studied in the Alexander Hills District, southeast of Death Valley National Park, a California Mojave Desert locality that produces: Precambrian stromatolites over a billion years old; early skeletonized eukaryotic cells of testate amoebae around three-quarters of a billion years old; and early Cambrian trilobites, archaeocyathids, annelid trails, arthropod tracks, and echinoderm material. Even though the ancient annelid tubes lie within reasonable proximity to the celebrated Gold Point trilobite beds, the exposed sedimentary material lying between the two areas is not in its original stratigraphic succession; that is to say, one cannot expect to encounter between the two areas an uninterrupted series of sedimentary layers representing a reliable transition from the oldest periods of deposition to the youngest. The explanation is that potent Earth forces during the Cenozoic Era, roughly 65 million years ago to present, block-faulted vast quantities of intervening strata, creating a jumbled messy mass of exposed rock deposits that only exacting geologic field mapping can hope to unravel. Fortunately for folks with paleontological zeal, the disruptive geologic upheavals did not obliterate all of those wonderful Early Cambrian plants and animals that once thrived here in the primordial timelessness of the geologic past. In addition to the prized trilobite exoskeletons--most commonly found as disarticulated, isolated cephalons and thoracic segments--the Gold Point locality also yields a wide assortment of interesting fossil organisms. These include such extinct species as archeocyathids (cup-to conical-shaped creatures whose morphological aspect resembles a cross between a coral and a sponge--they were for decades considered members of a unique Phylum of animals, but closer scrutiny suggests that they are more closely allied with the sponges, and so today most paleontologists categorize archeocyathids as an extinct variety of calcareous sponge) and salterella (an ice-cream-cone to tusk-shaped specimen roughly 6 to 8 millimeters long that many investigators originally conjectured represented one of the earliest examples of a cephalopod--sort of a distant ancestor of the ammonite--but more detailed analyses concluded that it was most likely a unique animal deserving of its own zoological Phylum called Agmata, a group that never survived beyond Early Cambrian times)--in addition to annelid trails, arthropod tracks, cyanobacterial blue-green algal bodies (the widespread Girvanella, a peculiar rounded concretionary specimen characteristic of pure, uncontaminated limetones deposited during latest Early Cambrian times in what is now the Great Basin), and brachiopod casts and molds. All of these specimens occur in strata originally mapped as the lower Cambrian Harkless Formation, although the shales and shaly limestones that yield the trilobites certainly resemble correlative rocks known as the Saline Valley Formation, whose type locality (the place where a geologic rock formation was first described in the scientific literature) lies over in the Waucoba Spring area in northwestern Death Valley National Park. The informally named Waucoba District used to be a rewarding area to explore for Early Cambrian fossils. Needless to report, the entire district, since 1994, has been included in the national park system and is therefore presently off-limits to any manner of unauthorized collecting. The fossiliferous sections at the Gold Point locality are composed of alternating brownish shales, greenish-orange shales, reddish-brown limy shales, orange-brown limestones, and dark-gray limestones (indeed, a rather colorful outcropping of various rock lithologies.). Almost all of the trilobites occur in the thin interbeds of dark-gray limetones that outcrop intermittently along the hillsides. This is certainly a classic Early Cambrian fossil locality. Even though the vast majority of trilobite specimens will be both fragmental and rather small--most cephalons range from one-quarter to one-half inch in diameter (or, 6 to 12 millimeters in metric measurement)--the sheer abundance and diversity of arthropod remains in the rocks here is truly phenomenal and inspiring. Trilobite varieties identified include Paedeumias granulata, Wanneria walcottana, Bonnia caperata, Olenoides ssp, Ogyopsis batis, Goldfieldia pacifica, Stephenaspis sp., Stephenaspis avitus, Zacanthopsis sp., Zacanthopsis contractus, Zacanthopsina eperephes, Syspacephalus, and four additional species as yet undescribed. Credit for discovering this remarkable trilobite-bearing district goes to two geologists with the United States Geological Survey. They came across the site during reconnaissance for a geological field mapping project. In 1960, a USGS paleontologist happened to examine fossil material collected from the Gold Point site. By all accounts, the extraordinary suite of trilobite specimens immediately "floored him," as it were, and led to his identification of the largest single assemblage of Early Cambrian trilobites yet described from North America. It should be pointed out right about now that although the Gold Point arthropods have already been officially documented in the scientific literature, a number of additional trilobite localities in Esmeralda County remain under formal paleontological investigations--hence, their exact position of occurrence cannot be divulged at this time, at least not until they have been described in monographic detail by the paleontologists involved in the investigations. Indeed, I have been sworn to secrecy (under penalty of torture by a trilobite's pygidium) not to reveal at least three other world-class Early Cambrian fossil sites within Esmeralda County--places that yield a plethora of identifiable trilobite specimens, including not a few perfect, intact exoskeletons. Once at the Gold Point fossil site, most collectors concentrate on the many fine trilobite fossils they find along the more moderately inclined, easily negotiated slopes. This is certainly acceptable behavior, an individual choice of course, but additional trilobite-yielding horizons can be discovered all along the axis of the Gold Point region, within the more rugged topography. Also, a wider variety of fossil remains can be sampled, including: archeocyathids (restricted to thin carbonate horizons interbedded with the shales); ichnofossil worm trails and undetermined arthropod tracks (present locally on greenish quartzitic sandstones and shales); brachiopod molds and casts (usually observed on reddish-brown shales); Girvanella (nodule to concretionary oval specimens in grayish-blue massive limestones secreted by an extinct species of cyanobacterial blue-green algae); and salterella (seen in orange-brown shaly limestones at irregular intervals--locally quite abundant, forming coquinas in which the argillaceous carbonate matrix is composed almost entirely of the 6 to 8 millimeter long ice-cream-cone-shaped specimens). Although none of the non-trilobite specimens is overly abundant here (except for the salterella, which is locally quite prolific), their presence in a least moderate numbers this far down in the lower Cambrian stratigraphic section makes the moderate hiking required to find them a most memorable and rewarding field experience. Of course, not every outcrop in the Gold Point fossil zone will yield something remarkable, but there is definitely enough 518-million-year-old paleontology available to keep even the most jaded explorer in fossil ecstasy. Here is an important fossil locality that gives us a rare opportunity to look back in geologic time to the surprising diversity and complexity of an Early Cambrian sea, some 518 million years ago. That so many biologically successful creatures should have thrived so long ago, and through the eternity of eons, seems to defy all that we believe to be law. Yet, when we hold in our hands the incontrovertible evidence of a creature with eyes in the rocks: a trilobite's eyes that gaze back into our own from ages past, we finally come to realize that those 518 million revolutions around the sun can no longer separate us. |
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Click on the images for larger pictures. From left to right: Image 1--the jeep at bottom center is parked at one of many fossil localities at the Gold Point fossil locality, Esmeralda County, Nevada; Image 2--a paleontology enthusiast stands at the base of a trilobite-bearing hill, which is composed of the Lower Cambrian Harkless Formation, roughly 518 million years old. The trilobites occur in thin interbeds of dark-gray limestones that outcrop from the base of the hill to roughly half way up the slope; Image 3--Exposures of the Lower Cambrian Harkless Formation at the Gold Point fossil area ; the lower slopes are composed of recessive-weathering greenish shales and quartzites, while more resistant, ledge-forming carbonates cap the ridges. |
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Click on the images for larger pictures. Left to right: Image 1--A slab of limestone from the Lower Cambrian Harkless Formation; contains many disarticulated trilobite remains; Image 2--Trilobite cephalons and cephalon molds on a chunk of limestone from the Gold Point fossil zone; mostly complete cephalon in center of image is Wanneria walcottana; Image 3--A cephalon of Wanneria walcottana from the Gold Point fossil site, Lower Cambrian Harkless Formation. |
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Click on the images for larger pictures. All specimens are trilobite cephalons from the Lower Cambrian Harkless Formation, Gold Point fossil site, Esmeralda County, Nevada. Left to Right: Image 1--Wanneria walcottana; Image 2--Paedeumias granulata; Image 3--Paedeumias granulata. |
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Click on images for larger pictures. All three images depict salterella coquinas from the Lower Cambrian Harkless Formation, Gold Point fossil locality, Esmeralda County, Nevada. Salterella is a curious critter that never made it beyond Early Cambrian times. In the late 1970s salterella was placed into its own distinct Phylum, called Agmata, after having been considered an early, primitive variety of cephalopod for many decades; curiously, only a few feet above the salterella coquina beds in the Harkless, salterella completely disappears from the fossil record--one naturally wonders, then, if their amazing abundance in the Harkless Formation records the precise moment in geologic time when salterella became extinct, dying out in perhaps a catastrophic mass demise. |
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Click on the images for larger pictures. From left to right: Image 1--Girvanella algae bodies (dark oval to circular structures; precipitated by an extinct type of cyanobacteri, a blue-green algae; Image 2--Archeocyathids in a chunk of limestone from the Lower Cambrian Harkless Formation, Gold Point fossil area, Esmeralda County, Nevada. The archeocyathids are the orange-brown conical specimens embedded on the matrix. Ever since they were first described, archeocyathids have been assigned by paleontologists to many different animal groups, primarily the corals and Pleosponges; many researchers even referred to them to a distinct, separate Phylum, Archeocyatha. But more recent investigations have proved pretty conclusively that archeocyathids were an early experiment in the Phylum Porifera--they are now generally considered an extinct type of calcareous sponge.; Image 3--slender archeocyathids from the Lower Cambrian Harkless Formation, Gold Point fossil area; probably the specimens can be assigned to the rather common genus Ethmophyllum. |
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