DIGGING ANCIENT DIRT:
THE JOHN DAY FOSSIL BEDS
Story by Vicki Andersen
From the soaring peaks of the snow-clad Cascade mountains and their adjacent year-round playgrounds (see April-May 2008 for "Creation of the Cascade Mountains"), our geological exploration of the Northwest leads us in the other direction: digging in the dirt.
While some rockhounds seek out samples laced with shimmering minerals, elusive
gemstones or concealed treasures like thundereggs, another group of excavators
use small hammers and trowels to pursue tangible evidence of life before man
trod the earth. These are the fossil hunters, and one of the richest research
grounds beckons from Central Oregon.
Fossil-Rich Blue Basin (Photo: USGS)
Columnar Basalt Pillars of the Clarno Palisades (Photo: USGS)
In the early 1860s, about the time Charles Darwin was turning scientific and pious worlds upside down with his theory of evolution, an Oregon clergyman and pioneer geologist encountered fossilized teeth and bones gathered in Central Oregon by a cavalry troop. Thomas Condon realized this was important evidence supporting Darwin's premise, and in 1865 he began searching the John Day Valley for more samples, eventually uncovering a wealth of paleontology specimens. His numerous investigations lead to his 1872 appointment as Oregon's first state geologist.
Situated within the deeply eroded layers of volcanic ash that makes up what is called the John Day Formation is a well-preserved history of the flora and fauna that flourished during 40 million years of the Cenozoic Era, known as the "Age of Mammals and Flowering Plants". Described as the world's richest fossil beds from this Era, it is one of the Earth's most complete records of prehistoric life.
More than 100 different species of mammals have been uncovered, including some of the earliest rhino fossils in the world. The John Day Fossil Beds have yielded at least 14 different species of horses, who first evolved in North America 50 million years ago.
These fossils show that jungles, savannas and woodlands once prospered in this
present-day region of scenic badlands known as the John Day River Basin. Over
14,000 acres were designated the John Day Fossil Beds National Monument in 1975,
comprised of three separate units encompassing more than 700 fossil sites, and
continuing field investigations are still uncovering new finds.
Cathedral Rock & its Band of Volcanic Tuff (Photo: NWIA)
Bridge Along the Blue Basin Trail (Photo: USGS)
SHEEP ROCK UNIT
Situated six miles west of Dayville, at the intersection of State Routes 26 and 19, stunning geological formations in the Sheep Rock Unit include Cathedral Rock which broke off the John Day Formation, slipped down a lofty precipice and caused the John Day River to reroute itself into a horseshoe bend around the base of the massive Rock.
The blue-green volcanic ash of Blue Basin, a huge natural amphitheater sculpted out of the John Day Formation, has turned to claystone. As this badlands-type outcropping continues to erode, it yields a large variety of the most valuable fossils found in the John Day region.
The gently inclined half-mile Island in Time Trail terminates above Blue Basin, and features interpretive signs and fossil replicas. The more strenuous 3-mile Blue Basin Overlook Trail climbs six hundred feet to the rim of its namesake, offering spectacular views of the John Day River Valley.
The Story in Stone Trail, an easy quarter-mile asphalt-surfaced path with short
sections of moderate incline, includes touchable exhibits of 25-30 million year-old
animal fossils embedded in the hillside. A self-guided brochure and audio-tape
tour (including cassette player) are available at the Visitor Center.
Sheep rock (Photo: USGS)
Picture Gorge (Photo: NWIA)
Sheep Rock, towering 1,100 feet above the John Day River, was monikered for the wild bighorn sheep which thrived here, as well as a later sheep ranch. The diagonal brown layer is a massive bed of volcanic ash known as a "tuff". Its colorful layers reveal fossils from a time when this region was covered by deciduous forests, approximately 25-28 million years ago, when it was home to three-toed horses, rhinos, oreodonts, sabertoothed cat-like animals, and lemur-like primates.
When the John Day River eroded a nearly 1,000-foot-long section out of the lava flow sixteen million years ago, it created Picture Gorge. Native Americans eventually turned this into an art gallery, decorating the walls with pictographs of people, animals and geometric designs.
The Thomas Condon Paleontology Center features exhibits, interpretive programs,
and audiovisual presentations about fossils, geology and paleontology. A window
peers into the laboratory where specimens from this region of still-active research
are prepared for scientific study.
Paleontology Museum Display of Lion & Sabertooth Cats & Rhino Skulls (Photo: USGS)
Blue Basin (Photo: USGS)
The Cant Ranch Historical Museum, located a quarter-mile away, serves as the
Monument headquarters and Visitor Center. Indoor and outdoor exhibits relate
the history of human settlement on the ranch and in the region. Wheelchair accessible,
you'll find a bookstore, restrooms, drinking fountains and shaded picnic area.
The Visitor Center is open daily from 9:00 a.m. to 5:00 p.m. (6:00 p.m. Memorial
Day to Labor Day) March through October, closed weekends and holidays Thanksgiving
Interpretive Panel at the Palisades (Photo: NWIA)
Clarno Palisades (Photo: Vicki Andersen)
Eighteen miles west of Fossil on State Route 218 are the bluffs of volcanic tuff and basalt flows known as the Clarno Unit. More than 300 species of plants have been identified in this area, and unusual primeval finds in the Hancock Mammal Quarry are still being investigated. Trails wind along lahars (volcanic mudflows) with embedded plant remains, through a subtropical forest that perished over 45 million years ago, passing near petrified logs and alongside 40 million year old fossils.
The Clarno Nut Beds were created when the surrounding tropical forest (including
banana palms!) was overwhelmed by a massive lahar. Over time the wood, leaves,
nuts and seeds of the forest bonded together to form deep, rich layers of fossilized
flora, fish and other fauna. Restrooms, drinking fountains and picnic areas
are available in this Unit.
Palisades Revealed by an Eroding Stream (Photo: USGS)
Large Diversity of Fossils were Preserved in the Palisades (Photo: Vicki Andersen)
The most prominent landform of the Clarno Unit is the Palisades, whose cliffs
are an extraordinary example of columnar basalt pillars. This type of landscape
forms when extra-hot, very fluid lava covers a large area. Cooling fairly evenly,
the lava shrinks and cracks, usually forming the most efficient geometric pattern:
hexagonal pillars. Two trails make their way from the bottom of the Palisades
for close-up surveillance of embedded remnants in the basalt.
This area is a treasure trove of fossils of tiny four-toed horses, huge rhino-like brontotheres, crocodilians, and meat-eating creodonts who roamed the ancient jungles.
Colorful Pallet of the Painted Hills (Photo: NWIA)
A Cuesta Crowns Carroll Rim (Photo: USGS)
PAINTED HILLS UNIT
The Painted Hills Unit is unsurpassed for geological splendor. Nine miles northwest of Mitchell off State Route 26, you will find hummocks and hillsides of heavily eroded volcanic ash layers bejeweled like an artist's palette. The weathering of ash and passage of diverse climatic periods has eroded and sculpted this section of the lower John Day Formation into dramatic panoramas of yellows and golds, tans and blacks, and pinks and reds.
Leaf Hill Trail, an easy quarter-mile path, passes through remnants of a 30 million year-old hardwood forest with fossilized leaf exhibits. Fossilized flora are typical of broad-leaf deciduous trees that grew on the edge of streams and lakes.
The similar-length Painted Cove Trail circles a crimson-tinted hill for close-up
inspection of the popcorn-textured claystone; trail guides can be found at the
trailhead The Painted Hills Unit also offers exhibits, restrooms, drinking fountains
and shaded picnic tables.
Painted Hills Overlook View of Carroll Rim (Photo: USGS)
Carroll Rim, capped by a massive volcanic tuff deposit called a "cuesta",
was a source of many fossils during the early exploration of this region. The
moderately strenuous three-quarter-mile Carroll Rim Trail climbs to the top
of this 500-foot tall prominence for a dazzling view of the Painted Hills and
nearby Sutton Mountain. The rock forming the cliffs along the trail is a layer
of welded volcanic ash known as ignimbrite.
John Day Fossil Beds National Monument (Photo: Vicki Andersen)
In the town of Fossil, behind the Wheeler County High School baseball field backstop, is a fossil bed rich in flora and chances of taking something home is good to excellent. Your daily collection limit is what you can hand-carry from the site in one trip to your vehicle, or about 25 pounds of rock.
Approximately 33 million years ago the Cascade Range spewed forth burst after
burst of volcanic ash which, along with organic material, washed into a lake
basin. As these layers built up and gradually hardened into stone, much of the
flora left well-defined impressions of leaves, fruit, cones, seeds and, infrequently,
flowers. Nearly three dozen plant species such as alder, beech, dawn redwood,
maple and pine have been identified, as well as animal fossils including an
unidentified bat, a new species of salamander, frogs and numerous insects.
Blue Basin (Photo: Vicki USGS)
Cathedral Rock & John Day River (Photo: USGS)
A site with a leaner but still potential chance to find fossils is near Mt. Vernon. On State Route 26 near milepost 144 is the intersection of Fields Creek Road. A couple hundred yards south on Fields Creek Road is an Oregon Department of Transportation geologic marker identifying a chalky embankment across the road. This formation is diatomaceous rock, consisting of the calcium remains from millions of minuscule aquatic animals called diatoms. Within these 12-15 million year-old diatomic remnants can be found fossilized deciduous leaves and snails -- in effect, fossils within fossils.
While collecting, digging or disturbing fossils or other geologic or biological resources is prohibited within the Monument, visitors are welcome to try their luck at the Fossil and Mt. Vernon sites.
Within the Monument, all drive-to overlooks have hard-packed surfaces. Park trails, overlooks and grounds are open during daylight hours. Trails and picnic facilities are open all year, and water is available at all picnic areas during the summer season. For brochures, maps or more information contact the John Day Fossil Beds National Monument, Kimberly, OR at 541-987-2333 or visit www.nps.gov/joda.
Vicki Andersen may be reached at: firstname.lastname@example.org.