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John Day Fossil Beds

National Monument


cover of park brochure

park geology subheading
layered rock formation
John Day Fossil Beds National Monument, Oregon

A unique treasure is concealed in the sculpted exposures of sedimentary rock of the John Day River Valley in central Oregon. Here are some of the richest fossil beds in the world, and they contain a record of remarkable continuity. Fossil beds that span even five million years are rare. Yet in this valley, the fossil record shows more than 40 million years of the diverse plant and animal life that existed here 45 million to 5 million years ago (mya). R.W. Chaney, a paleobotanist, once wrote that

"no region in the world shows more complete sequences of Tertiary
land populations, both plant and animal, than the John Day Basin."

It is a record of such continuity and duration that scientists can test theories against the fossil record.

Fossil beds contain vestiges of the actual soils, rivers, ponds, watering holes, mudslides, ashfalls, floodplains, middens, trackways, prairies, and forests. The rocks are rich with the evidence of ancient habitats and the dynamic processes that shaped them; they tell of sweeping changes in the John Day Basin. Great changes, too, have taken place in this area's landscape, climate, and in the kinds of plants and animals that have inhabited it. And it is all recorded in the fossil record.

Clarno Formation (50 - 35 mya)
Tropical to subtropical forests mantled the local terrain some 50 to 35 million years ago. We know of these forests because of a splendid sample of fossil seeds, nuts, fruits, leaves, branches, and roots. The Clarno nutbeds are among the finest fossil plant localities on the planet, with hundreds of species, many new to science, preserved. The conspicuous mammals were the browsing brontotheres and amynodonts, conspicuous because of their great size and ungainly appearance. Impressive too, were the strong-jawed scavengers, hyaenadonts, and ruggedly framed predators such as Patriofelis. Although a few of these animals lived into the early Oligocene (34 mya), they have left no modern descendants.

John Day Formation (37 - 20 mya)

The John Day Formation spans more than 15 million years. Even a cursory examination reveals that many types of environments existed in this landscape.

Deciduous forests replaced the earlier subtropical forests of the Clarno Formation. Numerous fossil plant localities containing a great number of different species indicate the vast biological diversity of the early Miocene epoch. More than 100 groups of mammals have been found in this formation as well, including dogs, cats, swine, oreodonts, horses, camals, rhinos, and rodents.

Multiple volcanic events during the deposition of the formation produced large amounts of volcanic ash. The resulting tuff, interspersed throughout the fossil-bearing beds, allows determination of accurate radiometric dates. The chronology derived from the tuff helps scientists determine the rate at which plants and animals changed as they evolved.

Mascall Formation (15 - 12 mya)
The interval between deposition of the John Day and Mascall times was marked by intermittent flows of basaltic lava that repeatedly leveled and denuded the region. By 15 million years ago, these eruptions had ceased and the basalt was weathering into soil. A moderate climate, sufficient precipitation, periodic deposits of volcanic ash, and the basaltic parent material combined to produce highly fertile soils, and from these soils arose lush, nutritious grasses and mixed hardwood forests, much like those found today in the eastern United States.

The Mascall savanna was home to a great variety of animals that we might recognize as horses, camels, and deer, as well as bears, weasels, dogs, and cats. Some dwelt in the woodlands, while others adapted to the grasslands. At the same time large mammals made a resurgence. Among them were the gomphotheres (early elephants), as well as sizable rhinos and bear-dogs.

Rattlesnake Formation (8 - 6 mya)
Named for Rattlesnake Creek, a minor tributary of the John Day River, the coarse deposits of the Rattlesnake Formation complete the paleontological story of the John Day Basin. Though they contain considerably fewer fossils than the Clarno, John Day, or Mascall formations, fragmented fossils have been found of horses, sloths, rhinos, camels, peccaries, pronghorns, dogs, bears, and others. It is an interesting population, with some species resembling those of today, and others those of a distant past. A preponderence of grazing animals over browsers suggest a much dryer and cooler climate, dominated by grasslands. These strata represent the last major episode of deposition in the basin. Erosion then began and continues to sculpt the landscapes of today.

Reconstructing the Past. The John Day Basin was first recognized as an important paleontological site in the 1860's, thanks to the ability of a young frontier minister, Thomas Condon, who recognized the fossil beds as a scientific treasure. At the time, paleontology, the study of ancient life, was still a new science. However, discoveries such as Condon's galvanized scientific interest. By the late 19th-century, researchers at Yale, Princeton, and the Smithsonian Institution had requested and received hundreds of specimens from the John Day Basin. They were then classified and described in the scientific literature. This early work set the stage for field paleontologists such as John C. Merriam, who in 1899 began the task of placing the John Day fossils in their geological, chronological, and paleoecological context. His efforts were instrumental in the preservation of this area.

Exploration and study of the John Day fossil beds continues today. In many of the beds, the fossils are widely scattered, and their occurrence cannot be predicted. Many types of fossils deteriorate rapidly once erosion exposes them to the elements. Thus the fossil beds are continually canvassed by paleontologists.

Each year hundreds of specimens are added to the National Park Service collection. Many of the items are mere fragments (a few teeth, for instance) but each specimen is accompanied by a wealth of field data:

  • coordinates that pinpoint both its geographical location and the stratigraphic position,
  • descriptions of features where it was deposited, and other data about its recovery.
This information, as well as that gained as the fossils are stabilized, prepared, and studied, is entered into museum records for use by scholars now and in the future.

Such collection efforts have provided researchers with scientifically significant samples, which open up intriguing avenues for research.

  • Paleontologists can now detect subtle shifts in the composition of ecosystems through time.
  • Researchers have identified and studied some ancient soils preserved in the John Day Basin and, from a distance of millions of years, are able to gauge former climatic conditions such as temperature.
  • Sedimentologists map the orientation of bones in a Clarno Formation quarry, and thereby plot the eddies, backwaters, and gravel bars of a river that flowed 37 million years ago.
  • Paleobotanists determine the rate at which plant communities evolved.
  • A biostratigrapher dates the last known occurrence of a fossil primate in North America.
Studies such as these combine to give us richly detailed pictures of the past.

park maps subheading

The General park map handed out at the visitor center is available on the park's map webpage.

For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.

photo album subheading

A photo album for this park can be found here.

For information on other photo collections featuring National Park geology, please see the Image Sources page.

books, videos, cds subheading

Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.

Please visit the Geology Books and Media webpage for additional sources such as text books, theme books, CD ROMs, and technical reports.

Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
ISBN 0-393-92407-6
9" x 10.75", paperback, 550 pages, full color throughout

The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!

Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.

geologic research subheading

Information about the park's research program is available on the park's research webpage.

For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.

The NPS maintains a searchable data base of research needs that have been identified by parks.

A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.

selected links subheading

NPS Geology and Soils Partners

NRCS logoAssociation of American State Geologists
NRCS logoGeological Society of America
NRCS logoNatural Resource Conservation Service - Soils
USGS logo U.S. Geological Survey

teacher feature subheading

Currently, we do not have a listing for any park-specific geology education programs or activities.

General information about the park's education and intrepretive programs is available on the park's education webpage.

For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.
updated on 01/04/2005  I   http://www.nature.nps.gov/geology/parks/joda/index.cfm   I  Email: Webmaster
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