Paleobotanical Field Trip To The Sailor Flat Hydraulic Gold Mine, California

A day of discovery with the FarWest Geoscience Foundation

Contents For The FarWest Geoscience Field Trip:

Field Trip To Sailor Flat Images: Fossil Leaves  Images; Petrified Wood Nevada City Weather

Links: My Music Links: My Fossils Pages  Links: USGS Papers   Email Address

FarWest Geoscience Foundation Field Trip


Click on the image for a larger picture. Several participants in the paleobotanical dig prepare to hike to the fossil plant locality in the Middle Eocene auriferous gravels (usually considered at least in part a correlative geologic time equivalent of the plant-bearing Eocene Ione Formation) in the western foothills of the Sierra Nevada, Nevada County, California--including group leader geologist David Lawler, seen standing in the back of the pick-up truck.

After meeting at Dennys Restaurant in Grass Valley by 9:00 in the morning, members of the FarWest Geoscience Foundation headed east in caravan style several miles to Sailor Flat, an abandoned hydraulic mine that yielded vast quantities of gold during the mid to late 1800s. At a convenient parking area above the old gold diggings, we consolidated forces and piled into several four-wheel drive vehicles for the final assault, a rough and sharply descending rocky ride over a primitive jeep trail to the bottom of the great hydraulic pit. 

We were after an unusually thick bed of the fossiliferous, world-famous chocolate-colored shales that are interbedded with the coarse, fluviatile (river-deposited) auriferous gravels--pebble to boulder-sized debris left behind some 50 to 40 million years ago by the Tertiary Yuba River Channel. In swampy, ponded areas along that ancient river channel, quiet-water lacustrine (lake) shales developed on the Eocene landscape and helped preserve an astounding variety of Early Cenozoic Era vegetation. Nearly 70 species of ancient plants have been described from what paleobotanists call the Chalk Bluff Flora, or those associations of fossil plants found in the Middle Eocene auriferous gravels exposed by hydraulic methods during the Gold Rush days of the mid to late 1800s--an awe-inspiring fossil flora whose overall composition resembles a modern subtropical Mexican Elm-Liquidamber forest at the foot of Mount Orizaba in Vera Cruz, Mexico. There are also similarities to such modern subtropical forests as those found along the Rio Moctezuma at Tomazunchale, Mexico; the Liquidamber-Oak and Mexican Elm forests near Coban, Guatemala; and the Liquidamber forests in the state of Morelos and the eastern Sierra Madre west of Tomazunchale, Mexico.


Click on the image for a larger picture. Participants in the paleobotanical dig assemble to hear group leader David Lawler (facing camera, at left-center of image) spell out the "rules of engagement." We were there to help uncover Middle Eocene fossil plants from so-called chocolate shale deposits in auriferous (gold-bearing) gravels left behind at the Sailor Flat hydraulic mine when gold seekers of the mid to late 1800s laid bare mile after mile of terrain in the northern Mother Lode of California while in search of the precious metal. All significant specimens went to the archival paleobotanical collections at the University California Museum of Paleontology.


Click on the image for a larger picture. David Lawler (left) instructs the group on what we need to know about how to proceed with the dig. Note the two small stakes in the ground,  topped by reddish flags; these mark the perimeters of three by three foot squares. Group members paired off and carefully excavated each specified roped-off area marked by one of those flags (each flag held a locality number that went into the permanent registry of fossil plant localities at the UC Museum of Paleontology).


Click on the image for a larger picture. David Lawler (upper center, with back to camera) and Dr. Diane Erwin (along slopes, bending to examine a fossil specimen), Collections Manager of Fossil Plants at the University California Museum of Paleontology, show the group what they're especially after--fossilized plants that reveal most if not all of the leaf margin, with excellent venation; other prized items from the chocolate shale deposits include beautiful examples of the original cuticle, which is that thin wax coating on the upper epidermis of leaves that helps protect against excessive water loss, mechanical injury, and fungal attack. In the Middle Eocene chocolate shales, exposed by hydraulicking methods during gold recovery, the original cuticle is locally quite abundant, appearing as a thin wax paper-like material that easily peels off the matrix upon direct exposure to the air; for this reason we were instructed to wrap it with urgent immediacy in tissue paper to prevent any loss of the invaluable substance--a genuine rarity in the fossil record. The fossil-bearing chocolate shales at the Sailor Flat locality are roughly 10 feet thick--anywhere from twice to three times the usual thickness observed at many of the abandoned hydraulic mines in the northern Gold Country of California.


Click on the image for a large picture. Participating members of the Farwest Geoscience Foundation begin to "attack" the chocolate shales, searching diligently with careful, gentle excavating techniques for identifiable fossil plants. David Lawler and crew had on hand loads of chilled bottled water and an assortment of soft drinks to keep well-hydrated the hard-working fossil seekers, treated to a glorious, unusually warm Autumnal afternoon in the Sierra Nevada foothills.


Click on the image for a larger picture. The late paleobotanist Howard Schorn, retired Collections Manager of fossil plants at the University California Museum of Paleontology, excavates the plant-bearing chocolate shales at Sailor Flat; he was vitally involved in a fascinating geological mystery story: Just how high was the ancestral Sierra Nevada during the geologic past? The traditional view, championed by the late paleobotanist Daniel I. Axelrod and others, is that the Sierra Nevada, as we know it today, is a relatively recent topographic expression, uplifted to its present dramatic elevations mainly during the past five million years--with most of that uplift occurring over the past three million years. But, studies based on rather recent sophisticated geophysical evaluations of mountain ranges, combined with paleobotanical leaf character analysis (study of leaf size, shape, venation,  and percentage of entire to serrated margins, among other parameters, to help determine the paleoclimate and paleoelevation of a given fossil site), have suggested quite strongly that the Sierra Nevada, along with the neighboring ancestral Great Basin region, stood just as high if not higher during the geologic past than at present.

Postscript: The conclusion is now concluded, as it were. What's decided, finally, is that the ancestral central to southern Sierra Nevada (roughly, Sierran areas south of Donner Pass) existed during Eocene times as a moderately low western slope to a high plateau region--the so-called Nevadaplano--that stretched eastward across present-day Nevada, an Eocene upland area that rose as high, if not higher, than the peak elevation seen there today. At around 16 million years ago, the Nevadaplano began to collapse, drop, through extensional geophysical strains associated with incipient formation of the Great Basin, eventually falling to present-day elevations by about 13 million years ago.

Which means, ultimately, that the central to southern Sierra has indeed been dramatically uplifted during the past five million years or so. On the other hand, Sierran regions from Donner Pass northward have remained at pretty much the same elevations as those that existed during deposition of the Eocene aurifierous gravels some 50 to 40 million years ago. So it so turns out that everyone involved in the Sierran elevation studies got it partially correct: the grand solution to the Sierra Nevada Eocene elevation problem turned out to be a major compromise. Axelrod got it mostly right, it turns out--around two-thirds of the Sierran length has indeed been greatly uplifted during the past five million years.

 
Click on the image for a larger picture. Dr. Diane Erwin (left), Collections Manager of Fossil Plants at the University California Museum of Paleontology, and Cathy Zyskowski collect fossil leaves from Middle Eocene "chocolate shales" at the Sailor Flat Hydraulic Mine in Nevada County, California, several miles east of Grass Valley/Nevada City (they are contiguous communities in the western foothills of the Sierra Nevada); all significant fossil specimens went to the archival paleobotanical collections at the University California Museum of Paleontology. The fossil locality presently lies on private property. Permission to collect here was kindly granted by the owners of the Sailor Flat hydraulic mine.


Click on the image for a larger picture. Fossil hunters with the Farwest Geoscience Foundation get down to business at Sailor Flat. Roll of TP in foreground on burlap sack is particularly useful for wrapping delicate leaf fossils filled with original remnants of the cuticle.


Click on the image for a larger picture. Eager members of the FarWest Geoscience Foundation explore the remarkably fossiliferous chocolate shales that gold seekers of the mid to late 1800s left behind at the Sailor Flat hydraulic mine. Practically every chunk of shale removed from this outcrop yielded complete and fragmental leaves and seeds from a roughly 48-million-year-old subtropical forest similar to a Mexican Elm-Liquidamber forest which grows today in the vicinity of Mount Orizaba, Vera Cruz, Mexico.
 


Click on the image for a larger picture. Two members of the FarWest Geoscience Foundation carefully inspect each piece of shale removed from the outcrop for Middle Eocene leaves and seeds. Note the clumps of manzanita behind the collectors, and the thick mixed conifer forest in the background. During Middle Eocene times, this very same area would have been a stagnant oxbow lake along a meandering river, where countless leaves and seeds from a subtropical forest fell into quiet, still, oxygen-poor waters and were eventually buried by extremely fine clays and muds, preserving the ancient vegetation in astounding detail.


A cliff face of unexploited gold-bearing bench gravels remaining from the days of hydraulic mining at the Sailor Flat Mine. Note the geology rock hammer at bottom center of image for scale. These younger auriferous gravels yielded far lower concentrations of gold than the justifiably famous "inner channel," or "blue ground," as the old-time hydraulickers referred to the relatively narrow and shallow channel incised into the Sierran bedrock, where vast quantities of gold accumulated during the earliest phases of sedimentary deposition. Nevertheless, the bench gravels contributed mightily to the estimated 12 million ounces of gold--worth roughly 5 billion dollars (at the old price of 20 dollars per ounce)-- removed from the ancestral Yuba River system by hydraulic methods.


A closer look at the auriferous bench gravels--composed mainly of quartz pebbles (rounded, white stones) and metamorphic clasts (darker colored material) set in a matrix of fine to coarse sand. Hydraulic mining initially began on a small scale in 1852, but soon developed into a widespread, sophisticated method of working  great volumes of gold-bearing gravels. The basic idea was to aim high-powered jets of water through huge nozzles at the auriferous gravels, washing away tons upon tons of debris, after which the gold-bearing debris/sludge traveled through a deep cut or tunnel that was lined with a series of sluices to capture the gold. During roughly a 30 year period, from 1855 to 1884, hydraulic miners washed way approximately 250 million cubic yards of material. This created repeated catastrophic flooding of farmlands and valuable property in the flatlands below the hydraulic operations. A farmer in Marysville by the name of Woodruff finally decided to sue the North Bloomfield Gravel Mining Company to prevent further debris from being discharged into the Yuba River. That case was heard by Judge Lorenzo Sawyer, who issued his famous "Sawyer Decision" in January of 1884--a 225 page document that effectively abolished large-scale hydraulic operations for all time.

Images Of Fossils Leaves


This is an essentially complete leaf from an ancient sycamore called Macginitiea, an extinct genus of Plane tree. A lucky member of the FarWest Geoscience Foundation found this specimen, with its original cuticle and all five points of the huge palmate leaf intact, during our dig at the Sailor Flat hydraulic mine. The stem, or petiole, is partially obscured by a chunk of shale matrix, but is also present. A rather fascinating find, indeed. Members of the Foundation collected at least four complete leaves of Macginitiea during our excursion to the Middle Eocene auriferous gravels at Sailor Flat. 


Here is a fossil leaf from a Chinkapin, Castanopsis--14 centimenters long--collected (several years ago) at the great Chalk Bluff hydraulic mine, several miles north of Colfax, California (a locality that is completely off-limits to unauthorized collecting, lying as it does on private property; explicit permission from the landowners must be secured before collecing fossils there)--the type locality for what has become known as the Chalk Bluff Flora, or the rich association of Middle Eocene fossil plants preserved in that distinctive deposit of chocolate shales exposed during hydraulicking operations throughout the northern Mother Lode country of California. The fossil plants collected at Sailor Flat during the FarWest Geoscience Foundation field trip also belong to this same Chalk Bluff Flora. And the chocolate shales and auriferous gravels which produce this amazing Eocene leaf deposit can be examined at most of the abandoned hydraulic mines in the Sierran foothills, from Iowa Hill south of Interstate 80 all the way north to La Porte in Plumas County.

The first historical mention of what today we call the Chalk Bluff Flora was made by a professor Whitney in an article published in the first volume of Geology in the early 1870s. The fossil plants were later described in detail in a truly remarkable paper, Report of the Fossil Plants of the Auriferous Gravel Deposits of the Sierra Nevada, by Leo Lesquereux, Memoirs of the Museum of Comparative Zoology at Harvard College, Volume 5, Number 2, 1878. But the definitive monograph on the Chalk Bluff Flora came in 1941 when H.D. MacGinitie published A Middle Eocene Flora from the Central Sierra Nevada, Carnegie Institute Of Washington Publication 534. Here, MacGinitie describes some 67 species of Eocene plants from the Chalk Bluff Flora, including such varieties as a cycad, palm, willow, hickory, walnut, alder, chinkapin, oak, fig, magnolia, cinnamon, laurel, swamp red bay, hydrangea, liquidamber, sycamore, cocoplum, Torrey Vauquelina, ailanthus, a member of the Bittersweet family, sumac, maple, buckthorn, loblolly-bay, lidfowers, tupelo, Indian-Almond, dogwood, persimmon, ash, satinleaf, and viburnum. Based on the overall environmental requirements of extant plants found in the fossil flora, MacGinitie concluded that the Eocene leaves accumulated in a subtropical climate, similar to that found today in the vicinity of Orizaba in southern Mexico, approximately 400 miles north of Guatemala; there, rainfall averages 60 to 80 inches a year, and the usual year-round temperature is close to 65 degrees, with no frost.

   

Left to right--Here is a complete leaf from a specimen that appears to represent what H. D. MacGinitie called Mallotus riparios in his classic monograph on the Chalk Bluff Flora, A Middle Eocene Flora From The Central Sierra Nevada, Carnegie Institute of Washington Publication 534, 1941. Mallotus riparios is most closely related to the living M. japonicus and M. tenuifolius, species now native to warm-temperate Japan and China--from Chekiang to western Hupeh and Szechwan. The specimen is 33mm long; collected several years ago at the great Chalk Bluff hydraulic gold mine (a locality that is completely off-limits to unauthorized collecting, lying as it does on private property; explicit permission from the landowners must be secured before collecint fossils there).

Right--This is a mostly complete leaf (the margin reveals minor degradation) from what paleobotanist H. D. MacGinitie in Carnegie Institute of Washington Publication 534 called Thuinopsis myricaefolia. It is among the most abundant specimens encountered in the Middle Eocene Chalk Bluff Flora. The leaf is 80mm long. T. myricaefolia is an extinct analog of the modern genera Thouinidium and Thouinia, both of which remain restricted in natural habitat to the tropics, growing from the West Indies to Central America. Collected by members of the FarWest Geoscience Foundation at the Sailor Flat hydraulic gold mine (a locality that is completely off-limits to unauthorized collecting, lying as it does on private property; explicit permission from the landowners must be secured before collecting fossils there).

   

Left to right-- A fossil leaf from a swamp red bay, genus Persea, whose relatives today live along perennially moist areas in the southeastern United States. The specimen is 8 centimeters long. It was collected several years ago from the Chalk Bluff hydraulic mine in Nevada County, California (a locality that is completely off-limits to unauthorized collecting, lying as it does on private property; explicit permission from the landowners must be secured before collecting fossils there). The specimen consists of essentially unaltered cuticle material remaining from the original leaf; unfortunately, portions of the cuticle (near the top of the leaf) had already weathered away before it was collected.

Right--a fragmental specimen of what appears to most closely resemble what paleobotanist H. D. MacGinitie figured as Quercus distinctus, a probable Eocene relative of Quercus agrifolia, the California Live Oak, or Coast Live Oak, which is now endemic primarily to the coastal ranges of southern and central California. The specimen is 60mm long. Collected by members of the FarWest Geoscience Foundation at the Sailor Flat hydraulic gold mine (a locality that is completely off-limits to unauthorized collecting, lying as it does on private property; explicit permission from the landowners must be secured before collecting fossils there).


Here are three more fossil leaf specimens from the Chalk Bluff hydraulic mine (a locality that is completely off-limits to unauthorized collecting, lying as it does on private property; explicit permission from the landowners must be secured before collecting fossils there), all preserved along the same bedding plane with a carbonized stem fragment (left edge of image); each of the leaves has miraculously retained its unaltered cuticle since Middle Eocene geologic times. The mostly complete specimen with the elongated stem at right edge is another swamp red bay, genus Persea (which includes avocados, as well)--it is 58mm long; the remaining two fragments are at present indeterminate.

Images Of Petrified Wood


Both sides of a piece of petrified wood--species indeterminate--from the Chalk Bluff hydraulic mine, Nevada County, California (a locality that is completely off-limits to unauthorized collecting, lying as it does on private property; explicit permission from the landowners must be secured before collecing fossils there). The specimen is 26 centimeters long. Petrified wood used to be quite abundant in the coarser auriferous gravel lenses during hydraulic mining days, and the old-time gold seekers removed great quantities of it while they blasted away entire mountainsides with their powerful jets of water, stacking the permineralized organic remains in sizable piles so that they would not interfere with gold extraction activities. Today, petrified wood is only common to locally abundant in the massive, abandoned surface mines, most of it having been carted away decades ago as curiosity pieces. A few rare, spectacular occurrences of petrified wood still exist, though, and the FarWest Geoscience Foundation continues to work hard, in collaboration with local land owners, the Bureau of Land Management and the US Forest Service to help preserve them for future scientific study.


Petrified wood, species indeterminate (a US nickel for scale on specimen at left), from the Buckeye Flat Diggings hydraulic mine, Nevada County, California (a locality that is completely off-limits to unauthorized collecting, lying as it does on private property; explicit permission from the landowners must be secured before collecting fossils there). Most of the petrified wood collected from the Chalk Bluff Flora has yet to be identified and described in the scientific literature--even though the material often displays almost life-like organic structure faithfully kept intact through silicification.

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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.
  • A Visit To Fossil Valley, Great Basin Desert, Nevada: Take a virtual field trip to a Nevada locality that yields the most complete, diverse, fossil assemblage of terrestrial Miocene plants and animals known from North America--and perhaps the world, as well.
  • 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.
  • Late Pennsylvanian Fossils In Kansas: Travel to the midwestern plains to discover the classic late Pennsylvanian fossil wealth of Kansas--abundant, supremely well-preserved associations of such invertebrate animals as brachiopods, bryozoans, corals, echinoderms, fusulinids, mollusks (gastropods, pelecypods, cephalopods, scaphopods), and sponges; one of the great places on the planet to find fossils some 307 to 299 million years old.
  • 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.
  • Early Cambrian Fossils Of Westgard Pass, California: Visit the Westgard Pass area, a world-renowned geologic wonderland several miles east of Big Pine, California, in the neighboring White-Inyo Mountains, to examine one of the best places in the world to find archaeocyathids--an enigmatic invertebrate animal that went extinct some 510 million years ago, never surviving past the early Cambrian; also present there in rocks over a half billion years old are locally common trilobites, plus annelid and arthropod trails, and early echinoderms.
  • 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.
  • Fossils In Millard County, Utah: Take virtual field trips to two world-famous fossil localities in Millard County, Utah--Wheeler Amphitheater in the trilobite-bearing middle Cambrian Wheeler Shale; and Fossil Mountain in the brachiopod-ostracod-gastropod-echinoderm-trilobite rich lower Ordovician Pogonip Group.
  • Paleozoic Era Fossils At Mazourka Canyon, Inyo County, California: Visit a productive Paleozoic Era fossil-bearing area near Independence, California--along the east side of California's Owens Valley, with the great Sierra Nevada as a dramatic backdrop--a paleontologically fascinating place that yields a great assortment of invertebrate animals.
  • 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.
  • In Search Of Fossils In The Tin Mountain Limestone, California: Journey to the Death Valley area of Inyo County, California, to explore the highly fossiliferous Lower Mississippian Tin Mountain Limestone; visit three localities that provide easy access to a roughly 358 million year-old calcium carbate accumulation that contains well preserved corals, brachiopods, bryozoans, crinoids, and ostracods--among other major groups of invertebrate animals.
  • 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.
  • Field Trip To A Vertebrate Fossil Locality In The Coso Range, California: Take a cyber-visit to the famous bone-bearing Pliocene Coso Formation, Coso Mountains, Inyo County, California; includes detailed text for the field trip, plus on-site images and photographs of vertebrate fossils.
  • 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.
  • 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.
  • For information on what can and cannot be collected legally from America's Public Lands, take a look at Fossils On America's Public Lands and Collecting On Public Lands--brochures that the Bureau Of Land Management has allowed me to transcribe.
  • In Search Of Vanished Ages--Field Trips To Fossil Localities In California, Nevada, And Utah--My fossils-related field trips in full print book form (pdf). 98,703 words (equivalent to a medium-size hard cover work of non-fiction); 250 printed pages (equivalent to about 380 pages in hard cover book form); 27 chapters; 30 individual field trips to places of paleontological interest; 60 photographs--representative on-site images and pictures of fossils from each locality visited.

United States Geological Survey Papers (Public Domain)

Online versions of USGS publications

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