Field Trip To The Copper Basin Fossil Flora, Nevada

Visit a remote fossil leaf locality in Nevada where some 42 species of 40-million-year-old plants have been identified from the Upper Eocene Dead Horse Tuff.

Take The Virtual Field Trip

Fossil enthusiasts looking for a remote and scenic area in which to find an abundance of well-preserved leaves, seeds and twigs might want to try Copper Basin in Nevada. The fossil site lies within a geologic rock formation called the Dead Horse Tuff, which is Late Eocene in age, dated by radiometric means at some 39 to 40 million years old.

Click on the image below for a larger picture. The view is northwest across scenic Copper Basin. Note the prominent outcrops of whitish tuffs of the Upper Eocene Dead Horse Tuff lying below the more massive reddish-brown rhyolite. Local concentrations of beautifully preserved, carbonized 40-million-year-old leaf impressions occur within minor tuffaceous shale accumulations interbedded in the predominantly volcanic terrain.

For the most part the Dead Horse Tuff is an unfossiliferous unit of pyroclastic debris, a crystal vitric tuff ranging in mineral composition from a biotite rhyolite to a biotite horneblende latite some 5,200 feet thick. But near the middle of the extensive accumulation of solidified volcanic ash--the remnants of a series of devastating explosive eruptions throughout Late Eocene times--minor interbeds of tuffaceous shales yield a treasure-trove of beautifully preserved deciduous leaves, conifer and maple samaras (winged flying seeds) and conifer foliage (primarily twigs, though cones and cone scales have been reported). The leaves in particular are typically preserved as bountiful carbonized impressions, organic tissues compressed through geologic time to shades of dark brown to black on a pale reddish-brown matrix. And because they are so spectacularly preserved, ranking as some of the finest examples of fossil plants in all the state of Nevada, many Dead Horse Tuff specimens have begun to appear in the inventories of commercial fossil dealers throughout the Western states. This is of course illegal activity, since no fossil specimen collected on Public Lands--and the Copper Basin locality lies amidst such a Bureau of Land Management-administered region--may be either sold or bartered; accordingly, commercial collectors must stay away from Copper Basin, or the entire fossil-bearing area will most certainly be closed down to all but professional paleobotanists representing either an accredited university or museum.

The usual admonitions may sound familiar to many regular travelers of the Great Basin, even laughably repetitious perhaps, but it is critical to remember that Copper Basin lies well off the proverbial beaten track. This is what the locals call the southeastern sector of "Owyhee Country," a sparsely populated Great Basin outback, if you will, where immediate medical or mechanical assistance is nonexistent. You may be able to find a ranch house somewhere out there, but don't count on it in a dire emergency. So, in order to assure a safe and enjoyable visit, those planning to visit the fossiliferous exposure of Dead Horse Tuff at Copper Basin must do so only in a reliable four-wheel-drive vehicle--or, at the very least, a rugged pickup truck whose tire tread can be trusted to carry you over lonesome stretches of semimaintained and unimproved dirt roads subject to washboarding, potholing and sudden washouts. You should also expect to encounter a variety of jagged rocks that tend to ruin even the toughest of tire treads: keep your speeds moderate to slow; there is nothing worse than blowing out more than one tire during a backcountry trek.

Click on the image below for a larger picture. Here is a complete leaf from a species of alder, Alnus jarbidgiana, the most common fossil plant variety encountered in the Upper Eocene Dead Horse Tuff at Copper Basin.

While in the deep backcountry, many a mile from Copper Basin, visitors will have an opportunity to observe the old site of Charleston, formerly one of the most isolated and lawless mining towns in all of Nevada. Nothing remains now to mark the site, save perhaps a couple of crumbling wooden buildings, but in a broader historical perspective Charleston has much to offer. Its general history has been discussed by many Nevada ghost town enthusiasts, including such notables as Stanley W. Paher and the inimitable Nell Murbarger, who in her classic work Ghosts Of The Glory Trail gives a riveting account of one of the last lynchings to take place in Elko County--it happened in Charleston.

The story has been told many time over; I hesitate to attempt another rendering of it here, but as I have already suggested the subject, I might as well join the prodigious body of folk who have already related the tale. Bear in mind that nobody has yet written the definitive account of what happened in Charleston in the 1880s. The general idea is that one George Washington Mardis, a Bible-thumping Old Testament preacher who gave stentorian sermons to his favorite burro "Sampson" made more-or-less regular trips from Charleston to a rather distant community for supplies. Prior to one his scheduled journeys, a local Chinese miner gave him $250 in gold to deliver to the county seat in payment of a debt.

Mardis obliged--but it was the last favor he would ever do for anyone on this earth. The next day miners from Charleston found his wagon and team of horses abandoned along the road, below town. In the dry, dead brush nearby they also came upon his remains, riddled with bullet holes. Apparently word had spread to the local criminal element (and there was no short supply of that commodity in Charleston) that Mardi was carrying with that extra gold worth 250 spondulix. A few of the miners at the scene of the crime decided to take a look around, playing amateur sleuth, to see what might turn up.

When one of them spotted near the body the tracks of a barefooted individual bearing six toes on the left foot, the search for the perpetrator immediately turned to the Chinese quarter in Charleston. The logic went something like this: Nobody, the investigators averred, but a person of Chinese ancestry would possibly go around without shoes in that harsh, unforgiving northern Nevada climate. Thus, a vigilante posse swooped down on Chinatown, yanking slipper after slipper from the left feet of everyone they happened to encounter. Eventually, after running through scores of normal feet, they came upon one lone male who exhibited that distinctive and incriminating extra toe.

The case was closed. They gave the six-toed individual two full days to devise any possible alibi; when none was forthcoming, the man was swiftly convicted on circumstantial evidence. The next day a suitable length of rope was procured and fashioned into the hangman's noose. And with most of the population of Charleston looking on--or taking part, as some accounts of the execution suggest--George Washington Mardis' murder case came to an inevitable ending.

Click on the image below for a larger picture. The view is roughly north, parked amidst Copper Basin, where some 42 species of fossil plants occur in tuffaceous, lacustrine (lake-deposited) exposures of the Upper Eocene Dead Horse Tuff.

The best way to find fossils at Copper Basin is to split with great care the partially silicified reddish-brown to creamy-white ashy shales of the Upper Eocene Dead Horse Tuff. Remove large chunks of the shales from the outcrop and, using either the pick or blunt end of a geology hammer (or even a broad putty knife, though a selection of large and small chisels would be a better idea here), forcefully rap the shales along their natural bedding planes. Usually, they will split with surprising ease to reveal a rewarding assortment of carbonized plant remains.

Some 42 species of fossil plants have been identified from the Dead Horse Tuff at Copper Basin. The most abundant forms encountered are fragmentary and, occasionally, complete leaves belonging to a species of alder called Alnus jarbidgiana.

In decreasing order of abundance, the nine next most-common remains include: an extinct redwood, Sequoia affinis (which is closely related to the modern coast redwood of northwestern California); leaves, from a tanbark oak; seeds, cone scales and twigs from a spruce; twigs from a second type of spruce; leaves from an Oregon grape; samaras and twigs from a fir, Abies cuprovallis; a second species alder, Alnus cuprovalis; and leaves from a sassafras, Sassafras ashleyi.

Click on the image below for a larger picture. Here are two fossil leaves from the Upper Eocene Dead Horse Tuff, Copper Basin, Nevada: at left is a fragmentary specimen of an alder, Alnus cuprovalis; at right is a complete leaf from the alder, Alnus jarbidgiana--both specimens are among the most common plant remains recovered from the Dead Horse Tuff.

Also present, but rather rarely found, are such varieties as cypress, hawthorn, plum yew, pine, maple, rhododendron, Prunus sp. (four species), eastern wahoo, buckeye, larch, willow, tree sparkleberry, madrone, currant, ocean spray, rose and leadplant.

It may come as no surprise to students of paleobotany that the first scientist to collect at Copper Basin was none other than the late Dr. Daniel I. Axelrod, who for decades was one of the very finest paleobotanists in the world. After learning of the locality through a private collector in Elko, Axelrod and his field assistant James F. Ashby made their first visit to Copper Basin in the spring of 1939. Axelrod said that they made only a small collection of plants on that date, due to the fact that the ground was still way too damp from the thawing snow pack of the previous winter. Subsequent visits in the summers of 1956, '59, and '61 through '63 netted a total of 5,343 specimens from the Upper Eocene Dead Horse Tuff--all of them now housed in the archival paleobotanical collections at the University California Museum of Paleontology in Berkeley, California.

Click on the image below for a larger picture. The view is roughly westward across a fossil plant locality in the Upper Eocene Dead Horse Tuff at Copper Basin. A fossil seeker explores the fine-grained tuffaceous shales for fossil plants.

Axelrod published his findings in a scientific, paleobotanical monograph. In it, Axelrod concluded that the fossil flora most closely resembled a number of modern conifer forests present in the western United States, among them the coast redwood and spruce-hemlock forest of northwestern California and the spruce-larch forests of the northern Cascade and Rocky Mountains. He also saw some obvious relationships to the spruce-fir and nearby conifer-deciduous hardwood forests of the eastern United States and to similar forest-type associations in China and Japan. Based on the environmental preferences of modern analogs of species identified from the Dead Horse Tuff, Axelrod suggested that the Copper Basin Flora was derived from a conifer-hardwood deciduous forest that lived close to the zone of montane conifers. Axelrod originally estimated that elevations at the site of deposition were probably in the neighborhood of some 3,600 feet; today the fossil site lies at 7,150 feet in a region regularly hit with wintertime weather extremes reminiscent of an Arctic environment. Recently, though, paleobotanists Howard Schorn and the late Jack A. Wolfe (passed away in August, 2005), among others, have concluded, through several avenues of independent scientific research (including a rigorous, sophisticated leaf character analysis study) that the entire ancestral Great Basin region likely existed during Later Eocene times as a broad plateau that stood as high, if not higher, than those elevations observed today; Schorn and Wolfe therefore estimate that the Copper Basin Flora accumulated at elevations roughly the same as those observed there today--in other words, around 7,200 feet.

Click on the image below for a larger picture. Looking roughly northward from a fossil leaf locality in the Upper Eocene Dead Horse Tuff. A paleobotany enthusiast searches for plant fossils. Here, near the middle of the thick, predominantly pyroclastic section, minor interbeds of fine-grained, tuffaceous lacustrine shales yield an abundance of excellently preserved fossil plants.

Yet, approximately 40 million years ago the Late Eocene climate could best be described as cool-temperate,with roughly 50 to 60 inches of rain per year--and that well distributed throughout the summer. There was no snow, except on the higher peaks surrounding the basin of deposition. The average yearly temperature was somewhere around 51 degrees, with mean temperatures for the warmest and coldest months of the year at around 58 and 44 degrees, respectively.

It was certainly a different world at Copper Basin some 39 to 40 million years ago--a broad lake basin within which volcanic ash periodically mixed with the fallen debris from deciduous plants and conifers to form a richly fossiliferous horizon in the Dead Horse Tuff. Today, collectors pry apart the hardened tuffaceous muds on a weathered ridge some 7,150 feet high in the glorious isolation of Nevada, finding a wealth of beautifully preserved fossil plants--a direct link with an age when a now extinct variety of coast redwood towered above thickets of alder, and the harshness of modern winters was yet to come.

 

 E-mail me at: Waucoba4@aol.com

Everyone's Invited To Visit My Other Web Sites

Paleontology-Related Pages

Web sites I have created pertaining to fossils

  • Fossils In Death Valley National Park: A site dedicated to the paleontology, geology, and natural wonders of Death Valley National Park; lots of on-site photographs of scenic localities within the park; images of fossils specimens; links to many virtual field trips of fossil-bearing interest.
  • Fossil Insects And Vertebrates On The Mojave Desert, California: Journey to two world-famous fossil sites in the middle Miocene Barstow Formation: one locality yields upwards of 50 species of fully three-dimensional, silicified freshwater insects, arachnids, and crustaceans that can be dissolved free and intact from calcareous concretions; a second Barstow Formation district provides vertebrate paleontologists with one of the greatest concentrations of Miocene mammal fossils yet recovered from North America--it's the type locality for the Bartovian State of the Miocene Epoch, 15.9 to 12.5 million years ago, with which all geologically time-equivalent rocks in North American are compared.
  • Fossils At Red Rock Canyon State Park, California: Visit wildly colorful Red Rock Canyon State Park on California's northern Mojave Desert, approximately 130 miles north of Los Angeles--scene of innumerable Hollywood film productions and commercials over the years--where the Middle to Late Miocene (13 to 7 million years old) Dove Spring Formation, along with a classic deposit of petrified woods, yields one of the great terrestrial, land-deposited Miocene vertebrate fossil faunas in all the western United States.
  • Fossil Plants Of The Ione Basin, California: Head to Amador County in the western foothills of California's Sierra Nevada to explore the fossil leaf-bearing Middle Eocene Ione Formation of the Ione Basin. This is a completely undescribed fossil flora from a geologically fascinating district that produces not only paleobotanically invaluable suites of fossil leaves, but also world-renowned commercial deposits of silica sand, high-grade kaolinite clay and the extraordinarily rare Montan Wax-rich lignites (a type of low grade coal).
  • Trilobites In The Marble Mountains, Mojave Desert, California: Take a trip to the place that first inspired my life-long fascination and interest in fossils--the classic trilobite quarry in the Lower Cambrian Latham Shale, in the Marble Mountains of California's Mojave Desert. It's a special place, now included in the rather recently established Trilobite Wilderness, where some 21 species of ancient plants and animals have been found--including trilobites, an echinoderm, a coelenterate, mollusks, blue-green algae and brachiopods.
  • A Visit To Ammonite Canyon, Nevada: Explore one of the best-exposed, most complete fossiliferous marine late Triassic through early Jurassic geologic sections in the world--a place where the important end-time Triassic mass extinction has been preserved in the paleontological record. Lots of key species of ammonites, brachiopods, corals, gastropods and pelecypods.
  • Late Triassic Ichthyosaur And Invertebrate Fossils In Nevada: Journey to two classic, world-famous fossil localities in the Upper Triassic Luning Formation of Nevada--Berlin-Ichthyosaur State Park and Coral Reef Canyon. At Berlin-Ichthyosaur, observe in-situ the remains of several gigantic ichthyosaur skeletons preserved in a fossil quarry; then head out into the hills, outside the state park, to find plentiful pelecypods, gastropods, brachiopods and ammonoids. At Coral Reef Canyon, find an amazing abundance of corals, sponges, brachiopods, echinoids (sea urchins), pelecypods, gastropods, belemnites and ammonoids.
  • Fossils From The Kettleman Hills, California: Visit one of California's premiere Pliocene-age (approximately 4.5 to 2.0 million years old) fossil localities--the Kettleman Hills, which lie along the western edge of California's Great Central Valley northwest of Bakersfield. This is where innumerable sand dollars, pectens, oysters, gastropods, "bulbous fish growths" and pelecypods occur in the Etchegoin, San Joaquin and Tulare Formations.
  • Field Trip To The Kettleman Hills Fossil District, California: Take a virtual field trip to a classic site on the western side of California's Great Central Valley, roughly 80 miles northwest of Bakersfield, where several Pliocene-age (roughly 4.5 to 2 million years old) geologic rock formations yield a wealth of diverse, abundant fossil material--sand dollars, scallop shells, oysters, gastropods and "bulbous fish growths" (fossil bony tumors--found nowhere else, save the Kettleman Hills), among many other paleontological remains.
  • A Visit To The Sharktooth Hill Bone Bed, Southern California: Travel to the dusty hills near Bakersfield, California, along the eastern side of the Great Central Valley in the western foothills of the Sierra Nevada, to explore the world-famous Sharktooth Hill Bone Bed, a Middle Miocene marine deposit some 16 to 15 million years old that yields over a hundred species of sharks, rays, bony fishes, and sea mammals from a geologic rock formation called the Round Mountain Silt Member of the Temblor Formation; this is the most prolific marine, vertebrate fossil-bearing Middle Miocene deposit in the world.
  • Middle Triassic Ammonoids From Nevada: Travel to a world-famous fossil locality in the Great Basin Desert of Nevada, a specific place that yields some 41 species of ammonoids, in addition to five species of pelecypods and four varieties of belemnites from the Middle Triassic Prida Formation, which is roughly 235 million years old; many paleontologists consider this specific site the single best Middle Triassic, late Anisian Stage ammonoid locality in the world. All told, the Prida Formation yields 68 species of ammonoids spanning the entire Middle Triassic age, or roughly 241 to 227 million years ago.
  • Fossil Bones In The Coso Range, Inyo County, California: Visit the Coso Range Wilderness, 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 the earliest known member of the genus Equus, which includes the modern horse and all other equids.
  • Fossil Plants At Aldrich Hill, Western Nevada: Take a field trip to western Nevada, in the vicinity of Yerington, to famous Aldrich Hill, where one can collect some 35 species of ancient plants--leaves, seeds and twigs--from the Middle Miocene Aldirch Station Formation, roughly 12 to 13 million years old. Find the leaves of evergreen live oak, willow, and Catalina Ironwood (which today is restricted in its natural habitat solely to the Channel Islands off the coast of Southern California), among others, plus the seeds of many kinds of conifers, including spruce; expect to find the twigs of Giant Sequoias, too.
  • Fossils From Pleistocene Lake Manix, California: Explore the badlands of the Manix Lake Beds on California's Mojave Desert, an Upper Pleistocene deposit that produces abundant fossil remains from the silts and sands left behind by a great fresh water lake, roughly 350,000 to 19,000 years old--the Manix Beds yield many species of fresh water mollusks (gastropods and pelecypods), skeletal elements from fish (the Tui Mojave Chub and Three-Spine Stickleback), plus roughly 50 species of mammals and birds, many of which can also be found in the incredible, world-famous La Brea Tar Pits of Los Angeles.
  • Field Trip To Pleistocene Lake Manix, California: Go on a virtual field trip to the classic, fossiliferous badlands carved in the Upper Pleistocene Manix Formation, Mojave Desert, California. It's a special place that yields beaucoup fossil remains, including fresh water mollusks, fish (the Mojave Tui Chub), birds and mammals.
  • Trilobites In The Nopah Range, Inyo County, California: Travel to a locality well outside the boundaries of Death Valley National Park to collect trilobites in the Lower Cambrian Pyramid Shale Member of the Carrara Formation.
  • Ammonoids At Union Wash, California: Explore ammonoid-rich Union Wash near Lone Pine, California, in the shadows of Mount Whitney, the highest point in the contiguous United States. Union Wash is a ne plus ultra place to find Early Triassic ammonoids in California. The extinct cephalopods occur in abundance in the Lower Triassic Union Wash Formation, with the dramatic back-drop of the glacier-gouged Sierra Nevada skyline in view to the immediate west.
  • A Visit To The Fossil Beds At Union Wash, Inyo County California: A virtual field trip to the fabulous ammonoid accumulations in the Lower Triassic Union Wash Formation, Inyo County, California--situated in the shadows of Mount Whitney, the highest point in the contiguous United States.
  • Ordovician Fossils At The Great Beatty Mudmound, Nevada: Visit a classic 475-million-year-old fossil locality in the vicinity of Beatty, Nevada, only a few miles east of Death Valley National Park; here, the fossils occur in the Middle Ordovician Antelope Valley Limestone at a prominent Mudmound/Biohern. Lots of fossils can be found there, including silicified brachiopods, trilobites, nautiloids, echinoderms, bryozoans, ostracodes and conodonts.
  • Paleobotanical Field Trip To The Sailor Flat Hydraulic Gold Mine, California: Journey on a day of paleobotanical discovery with the FarWest Science Foundation to the western foothills of the Sierra Nevada--to famous Sailor Flat, an abandoned hydraulic gold mine of the mid to late 1800s, where members of the foundation collect fossil leaves from the "chocolate" shales of the Middle Eocene auriferous gravels; all significant specimens go to the archival paleobotanical collections at the University California Museum Of Paleontology in Berkeley.
  • Early Cambrian Fossils In Western Nevada: Explore a 518-million-year-old fossil locality several miles north of Death Valley National Park, in Esmeralda County, Nevada, where the Lower Cambrian Harkless Formation yields the largest single assemblage of Early Cambrian trilobites yet described from a specific fossil locality in North America; the locality also yields archeocyathids (an extinct sponge), plus salterella (the "ice-cream cone fossil"--an extinct conical animal placed into its own unique phylum, called Agmata), brachiopods and invertebrate tracks and trails.
  • Fossil Leaves And Seeds In West-Central Nevada: Take a field trip to the Middlegate Hills area in west-central Nevada. It's a place where the Middle Miocene Middlegate Formation provides paleobotany enthusiasts with some 64 species of fossil plant remains, including the leaves of evergreen live oak, tanbark oak, bigleaf maple, and paper birch--plus the twigs of giant sequoias and the winged seeds from a spruce.
  • Ordovician Fossils In The Toquima Range, Nevada: Explore the Toquima Range in central Nevada--a locality that yields abundant graptolites in the Lower to Middle Ordovician Vinini Formation, plus a diverse fauna of brachiopods, sponges, bryozoans, echinoderms and ostracodes from the Middle Ordovician Antelope Valley Limestone.
  • Fossil Plants In The Dead Camel Range, Nevada: Visit a remote site in the vicinity of Fallon, Nevada, where the Middle Miocene Desert Peak Formation provides paleobotany enthusiasts with 22 species of nicely preserved leaves from a variety of deciduous trees and evergreen live oaks, in addition to samaras (winged seeds), needles and twigs from several types of conifers.
  • Early Triassic Ammonoid Fossils In Nevada: Visit the two remote localities in Nevada that yield abundant, well-preserved ammonoids in the Lower Triassic Thaynes Formation, some 240 million years old--one of the sites just happens to be the single finest Early Triassic ammonoid locality in North America.
  • Fossil Plants At Buffalo Canyon, Nevada: Explore the wilds of west-central Nevada, a number of miles from Fallon, where the Middle Miocene Buffalo Canyon Formation yields to seekers of paleontology some 54 species of deciduous and coniferous varieties of 15-million-year-old leaves, seeds and twigs from such varieties as spruce, fir, pine, ash, maple, zelkova, willow and evergreen live oak
  • High Inyo Mountains Fossils, California: Take a ride to the crest of the High Inyo Mountains to find abundant ammonoids and pelecypods--plus, some shark teeth and terrestrial plants in the Upper Mississippian Chainman Shale, roughly 325 million years old.
  • Field Trip To The Copper Basin Fossil Flora, Nevada: Visit a remote region in Nevada, where the Late Eocene Dead Horse Tuff provides seekers of paleobotany with some 42 species of ancient plants, roughly 39 to 40 million years old, including the leaves of alder, tanbark oak, Oregon grape and sassafras.
  • Fossil Plants And Insects At Bull Run, Nevada: Head into the deep backcountry of Nevada to collect fossils from the famous Late Eocene Chicken Creek Formation, which yields, in addition to abundant fossil fly larvae, a paleobotanically wonderful association of winged seeds and fascicles (bundles of needles) from many species of conifers, including fir, pine, spruce, larch, hemlock and cypress. The plants are some 37 million old and represent an essentially pure montane conifer forest, one of the very few such fossil occurrences in the Tertiary Period of the United States.
  • A Visit To The Early Cambrian Waucoba Spring Geologic Section, California: Journey to the northwestern sector of Death Valley National Park to explore the classic, world-famous Waucoba Spring Early Cambrian geologic section, first described by the pioneering paleontologist C.D. Walcott in the late 1800s; surprisingly well preserved 540-510 million-year-old remains of trilobites, invertebrate tracks and trails, Girvanella algal oncolites and archeocyathids (an extinct variety of sponge) can be observed in situ.
  • Fossils From The Savage Canyon Formation, Nevada: Images of fossil plants and an insect from a classic Middle Miocene geologic rock formation in Nevada.
  • Petrified Wood From The Shinarump Conglomerate: An image of a chunk of petrified wood I collected from the Upper Triassic Shinarump Conglomerate, outside of Dinosaur National Monument, Colorado.
  • Fossil Giant Sequoia Foliage From Nevada: Images of the youngest fossil foliage from a giant sequoia ever discovered in the geologic record--the specimen is Lower Pliocene in geologic age, around 5 million years old.
  • Some Favorite Fossil Brachiopods Of Mine: Images of several fossil brachiopods I have collected over the years from Paleozoic, Mesozoic and Cenozoic-age rocks.

United States Geological Survey Papers (Public Domain)

Online versions of USGS publications

Return To Fossils In Death Valley National Park