John Day Fossil Beds National Monument
| John Day Fossil Beds National Monument | |||
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| Location: | Oregon , United States | ||
| Specialty: | Findings of fossils from the geological periods Paleogene and Neogene | ||
| Next city: | The dalles | ||
| Surface: | 56.7 km² | ||
| Founding: | October 26, 1974 | ||
| Visitors: | 124,900 (2005) | ||
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The John Day Fossil Beds National Monument is a protected area by the type of National Monuments in the US -Bundesstaat Oregon . It consists of three non-contiguous parts, so-called units , which lie along about 100 kilometers in the river valley of the John Day River . Sites with fossils of living beings from the geological periods Paleogene and Neogene with an age of around 44 to 6 million years are protected . The exposed layers themselves span a period of around 54 to 6 million years.
Between 1931 and 1965, the parts of today's National Monument were designated as state parks by the state of Oregon . In 1974 they were included in the federal government's protection program and placed under the administration of the National Park Service .
description
All three parts of the John Day Fossil Beds National Monument are located in northeast Oregon, east of the Cascade Range in the valley of the John Day River, a tributary of the Columbia River . The region is characterized by a semi-arid climate with dry, hot summers and cold winters. The precipitation falls almost exclusively in spring and varies between 230 and 400 mm per year.
The river itself is the only year-round watercourse in the reserve. He is accompanied by a soft wood meadow, in his environment live elk and mule deer , American mink and Canadian beaver . The North American otter , exterminated by hunting , has been reintroduced.
The Sheep Rock Unit of the area is located in Grant County , between the towns of Kimberly and Dayville . This is where the Thomas Condon Paleontology Center with its research laboratories and an exhibition on paleontology is located, and the neighboring Cant Ranch , the headquarters of the conservation area administration, with an exhibition on the cultural history of the region. In this part with the youngest rocks lie the striking Sheep Rock and an area of Badlands known as the Blue Basin , as well as the Picture Gorge , a gorge of the John Day River, in which many rock paintings of the indigenous people were found.
The Painted Hills Unit is located in Wheeler County 15 km west of Mitchell in the basin of the John Day River on Bridge Creek and is characterized by strikingly colored layers of rock. Minerals are embedded in the clay stones of the gentle hills , which color them in yellow, gold, black and red tones, which seem to change with the light over the course of the day and the weather. In the 1920s and 1930s, predominantly petrified plants were found in the soft rock, giving an insight into the climatic conditions around 33 million years ago.
In the Clarno Unit , also in Wheeler County and 35 km west of the village of Fossil , the oldest and hardest rocks are exposed . They were formed around 44 million years ago during a volcanic eruption. The Clarno Palisades are steep cliffs with sharp erosion shapes and a naturally formed stone arch .
geology
Along the John Day River you can climb upstream through the history of the earth and into ever younger geological layers . The long span of time and the completeness of the layers as well as the wealth of plant and animal fossils in the reserve make it very important for the study of geology and paleontology. The following description of the stratigraphic rock units follows the sequence of their formation and progresses from the older to the younger layers.
Clarno formation
The Clarno Formation contains the oldest rocks in the area, formed in the Eocene ( Paleogene ) about 54 million years ago. About 44 million years ago a lahar , a mud flow from a volcanic eruption, buried a largely stable, subtropical forest for a long time . In the petrified sediments between the mud flows, over 175 different plant species of this forest have been found and documented. Because of the high number of walnuts and other seeds and fruits, the deposits are known as Clarno Nut beds . There are also a large number of insect fossils . The early mammals are represented by Patriofelis (from the extinct group of Oxyaenodonta ), Hyrachyus (a relative of today's tapirs and rhinos) and Xylotitan (a member of the also extinct Brontotheriidae , relative of the horses). Crocodiles and catfish-like bony fish lived in the swamps . A very well-known, but somewhat more recent fossil site that produced outstanding mammal finds from this formation is the Hancock Mammal Quarry . There is a former swampy river arm with an age of about 40 million years, in whose sediments the petrified bones of Haplohippus (a small original horse), Eubrontotherium , Achaenodon (a relative of today's pigs) and the large scavenger Hemipsalodon occur. Some of these species are only found here worldwide. Also of importance are five complete rhinoceros skulls, which were originally called Clarno Rhinos and today represent the basal rhinoceros genus Teletaceras .
John Day formation
The John Day Formation consists predominantly of clay and sandstone that was deposited at the end of the Paleogene and the Early Neogene (aged 39 to 18 million years). The John Day Formation is divided into several geological sub-units, the so-called members.
- Bridge Creek Member: This unit contains numerous animal and plant fossils at 33 mya . The plant fossils indicate that the region's climate had become cooler and drier. For the first time, the seasons caused a change in living conditions. The forests were shaped by the primeval sequoia . Because the rocks of the area were formed from deposits of a river, almost only aquatic life can be found: fish, amphibians, insects and a few birds. Only a few bats have survived in mammals.
- Turtle Cove Member: The rocks in this unit are predominantly blue-green volcanic ash . A fossil find about 29 million years old indicates that the climate had become drier again. Hardwood forests dominated the landscape. In them lived three- toed horses, deer piglets , beavers, oreodontas and nimravidae . The Amphicyonidae dominated the carnivores .
- Kimberly-Member: The rocks of this stratigraphic unit are gray to slightly pink. They emerged from clayey ash deposits. The most important fossil site is around 24 million years old. The fossils suggest that the landscape was heavily forested. The tree species found, birch , elm , maple and oak were already quite similar to today's. When it comes to animal fossils, rodents that lived in burrows stand out. The first dogs appeared among the predators , and Amphicyonidae continued to live next to them.
- Haystack Valley Member: A fossil deposit in the sand and ash deposits of the alluvial cone of a continental basin , which later hardened to sandstone with embedded tuffs, is around 20 million years old . At the same time, the layers of tectonic forces were lifted and tilted with a slight dip from west to east. The gradient created rivers and watercourses that dug deep into the relatively soft rock. Due to the rivers, the landscape was mostly overgrown with softwood species such as poplars and alders , alongside large areas of bushes on young alluvial land. The animal world was characterized by large mammals such as rhinos and chalicotheria , horses and camels lived in more open areas . This layer already belongs to the Neogene , since the Paleogene / Neogene border is currently geochronologically dated to about 23 million years ago.
Picture Gorge Basalt
About 18 to 15 million years ago, the entire region of today's protected area was covered by basaltic lavas: the Columbia plateau basalt . The thin but continuous flood basalt layer is free of fossils.
Mascall formation
Tufa banks and sandstones alternate above the Picture Gorge basalt. They were deposited between 15 and 12 million years ago. The tufa banks were created from volcanic ash and the sand and silt stones can be interpreted as floodplain sediments. The tuff layers in particular are rich in fossils. The landscape was flat, reminiscent of today's savannah with lakes crossed by wide, slow-flowing streams and rivers. Horses, camels and umbilical pigs lived in the area , as well as early relatives of the elephants called Gomphotherium . In addition, the first cats from Asia immigrated to the region. Oreodonta are found for the last time and subsequently became extinct.
Rattlesnake formation
The youngest rocks in the reserve are around 6–7 million years old. They are made of tuff and emerged from the streams of ash from massive volcanic eruptions. As stored fossils show, the region was previously largely free of trees, a steppe with a few bushes covered the landscape. Horses, elephants , camels, rhinos and pronghorns lived in it on large grazers. Umbilical pigs, short -faced bears , cats, dogs and two-toed sloths lived next to them .
history
The basin of the John Day River was only sparsely populated by Indian peoples because of the harsh climate and the low fertility of the soil. Northern Paiute , Umatilla , Wasco, and the Warm Springs Indians moved in small groups through the prairies east of the Cascade Range. From the 1840s, the first whites came to Oregon, which was jointly colonized by the United States and Great Britain . After the Whitman massacre of 1847 in nearby Walla Walla , in which Cayuse and Umatilla attacked the mission station of Marcus Whitman, there were continued conflicts between Indians and settlers, and the militia intervened several times, until 1855 all Indians in the region on reservations were forced and they had to largely give up their traditional way of life.
The story of the fossil finds in the bed of the John Day River begins with Thomas Condon (1822–1907). He had come to The Dalles , Oregon as a pastor and missionary and heard from prospectors around 1862 that they had found fossilized bones. In 1865 he set out for the first time to look for the sites himself. He found individual fossils in various places, the best finds he made on the John Day River.
Condon was self-taught . He ordered literature by mail, subscribed to natural history magazines, built up a collection, and met with all the scholars who came to the region. He gave public lectures on geology and paleontology in his church and school. In the late 1860s, Condon came into contact with a group of field geologists from the US Geological Survey who recognized his collection as exceptional.
In 1869 he sent some of the finds to natural history museums on the east coast of the United States, who were enthusiastic about the finds and ordered further material from Condon. In 1871, Yale University made the first field trip to the John Day River, guided locally by Condon. The University of California , the Smithsonian Institute and other institutions recognized the importance of the sites.
In 1872, Condon , who studied theology, was appointed geology professor at the newly founded State University of Oregon in Eugene . By 1900, specialist journals had published over 100 articles on the fossils of the John Day River, and every natural history museum in the world had obtained exhibits from the sites. The first work describing the region's palaeobotany appeared in 1902, and fossil research continued over the following decades. In 1956 the Hancock Mammal Quarry was found, a site of 40 million year old fossils containing a variety of endemic mammal species. It was researched until the 1980s.
From around 1925, the sites began to become a tourist destination. From 1931 to 1965, the state of Oregon purposefully purchased land to make the landscape and fossil sites accessible to the public. Since 1951, natural history and scientific courses have been held annually in the area for target groups from elementary school classes to doctoral students. In 1974, the three parts of the current protected area from the protection program of the state of Oregon were handed over to the federal government and designated as a national monument .
The National Monument today
Because of the decentralized structure with three units spread over a larger area, only a small part of the visitors perceives the entirety of the geological and paleological history of the monument. The conveyance of content is mainly done through educational trails and individual information boards.
The new Thomas Condon Paleontology Center opened in 2004. Visitor information, a fossil exhibition and the park's research center are housed under one roof. The excavation in the area continues. Both visiting scientists from various universities in the United States and abroad, as well as the permanent team of the National Park Service, carry out excavations, prepare the finds for the collection of the National Monument and research the flora and fauna of the region. In the last few years, the study of climate history has been added as a new task.
The old visitor center in the historic Cant Ranch near the Paleontology Center was subsequently rebuilt and, in addition to the management of the park, now houses an exhibition on the settlement and cultural history of the region. There are no accommodations, camping sites or restaurants in the park itself.
literature
- Frank Hall Knowlton: Fossile Flora of the John Day Basin, Oregon , United States Geological Survey, Washington, 1902 (also online in full: Fossile Flora )
- Thomas P. Thayer: Geologic Setting of the John Day Country, Grant County, Oregon , Pacific Northwest National Parks and Forests Association, 1990 (also online: Geologic Setting )
- Stephen Dow Beckham, Florence K. Lentz: Rocks & Hard Places - Historic Resources Study , National Park Service, United States Department of the Interior, Seattle, Washington, 2000 (also online in full: Rocks & Hard Places )
Web links
- National Park Service: John Day Fossil Beds National Monument (official site; English)
- National Park Service: The Present Unlocks the Past - Feature presentation of the monument ( Eng.- Adobe Flash required)
- US Geological Survey: John Day Fossil Beds National Monument - extensive image gallery from the National Monument on geological topics (3D or conventional images)
Individual evidence
- ↑ Steven R. Manchester: Fruits and seeds of the middle Eocene Nut Beds flora, Clarno Formation, Oregon. Palaeontographica Americana 58, 1994, pp. 1-205
- ^ EA Wheeler and SR Manchester: Woods of the Middle Eocene Nut Beds Flora, Clarno Formation, Oregon, USA. International Association of Wood Anatomists Journal Supplement 3, 2002, pp. 1-188
- ↑ Richard M. Dill Hoff, Thomas A. Dill Hoff, Regan E. Dunn, Jeffrey A. Myers and Caroline AE Strömberg: Cenozoic paleobotany of the John Day Basin, Central Oregon. In: JE O'Connor, RJ Dorsey and IP Madin (Eds.): Volcanoes To Vineyards: Geologic Field Trips Through The Dynamic Landscape Of The Pacific Northwest. Geological Society of America Field Guide 15, 2009, pp. 135-164
- ^ Matthew C. Mihlbachler and Joshua X. Samuels: A small-bodied species of Brontotheriidae from the middle Eocene Nut Beds of the Clarno Formation, John Day Basin, Oregon. In: Journal of Paleontology 90 (6), 2016, pp. 1233-1244 doi: 10.1017 / jpa.2016.61 .
- ^ Matthew C. Mihlbachler: Species taxonomy, phylogeny, and biogeography of the Brontotheriidae (Mammalia: Perissodactyla). Bulletin of the American Museum of Natural History 311, 2008, ISSN 0003-0090 (pp. 290-298)
- ^ C. Bruce Hanson: Teletaceras radinskyi, a new primitive rhinocerotid from the late Eocene Clarno formation of Oregon. In: Donald R. Prothero and Robert M. Schoch (Eds.): The evolution of perissodactyls. New York and London, 1989, pp. 379-398
- ^ C. Bruce Hanson: Stratigraphy and vertebrate faunas of the Bridgerian-Duchesnean Clarno Formation, north-central Oregon. In: Donald R. Prothero and Robert J. Emry (Eds.): The Terrestrial Eocene – Oligocene Transition in North America. Cambridge University Press, 1996, pp. 206-239