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John Day Fossil Beds National Monument is a U.S. National Monument in Wheeler and Grant counties in east-central Oregon. Located within the John Day River basin and managed by the National Park Service, the park is known for its well-preserved layers of fossil plants and mammals that lived in the region between the late Eocene, about 45 million years ago, and the late Miocene, about 5 million years ago. The monument consists of three geographically separate units: Sheep Rock, Painted Hills, and Clarno. The units cover a total of of semi-desert shrublands, riparian zones, and colorful badlands. About 184,000 people frequented the park in 2014 to engage in outdoor recreation or to visit the Thomas Condon Paleontology Center or the James Cant Ranch Historic District. Before the arrival of Euro-Americans in the 19th century, the John Day basin was frequented by Sahaptin people who hunted, fished, and gathered roots and berries in the region. After road-building made the valley more accessible, settlers established farms, ranches, and a few small towns along the river and its tributaries. Paleontologists have been unearthing and studying the fossils in the region since 1864, when Thomas Condon, a missionary and amateur geologist, recognized their importance and made them known globally. Parts of the basin became a National Monument in 1975. Averaging about in elevation, the monument has a dry climate with temperatures that vary from summer highs of about to winter lows below freezing. The monument has more than 80 soil types that support a wide variety of flora, ranging from willow trees near the river to grasses on alluvial fans to cactus among rocks at higher elevations. Fauna include more than 50 species of resident and migratory birds. Large mammals like elk and smaller animals such as raccoons, coyotes, and voles frequent these units, which are also populated by a wide variety of reptiles, fish, butterflies, and other creatures adapted to particular niches of a mountainous semi-desert terrain. ==Geography== The John Day Fossil Beds National Monument consists of three widely separated units—Sheep Rock, Painted Hills, and Clarno—in the John Day River basin of east-central Oregon. Located in rugged terrain in the counties of Wheeler and Grant, the park units are characterized by hills, deep ravines, and eroded fossil-bearing rock formations. To the west lies the Cascade Range, to the south the Ochoco Mountains, and to the east the Blue Mountains.〔 Elevations within the park range from .〔 The Clarno Unit, the westernmost of the three units, consists of located west of Fossil along Oregon Route 218. The Painted Hills Unit, which lies about halfway between the other two, covers . It is situated about northwest of Mitchell along Burnt Ranch Road, which intersects U.S. Route 26 west of Mitchell.〔 These two units are entirely within Wheeler County.〔 The remaining of the park, the Sheep Rock Unit, are located along Oregon Route 19 and the John Day River upstream of the unincorporated community of Kimberly.〔 This unit is mostly in Grant County, although a small part extends into Wheeler County.〔 The Sheep Rock Unit is further subdivided into the Mascall Formation Overlook, Picture Gorge, the James Cant Ranch Historic District, Cathedral Rock, Blue Basin, and the Foree Area. Some of these are separated from one another by farms, ranches, and other parcels of land that are not part of the park. The park headquarters and main visitor center, both in the Sheep Rock Unit, are northeast of Bend and southeast of Portland by highway. The shortest highway distances from unit to unit within the park are Sheep Rock to Painted Hills, ; Painted Hills to Clarno, , and Clarno to Sheep Rock, .〔 The John Day River, a tributary of the Columbia River, flows generally west from the Strawberry Mountains before reaching the national monument. It turns sharply north between the Mascall Formation Overlook and Kimberly, where the North Fork John Day River joins the main stem. Downstream of Kimberly, the river flows generally west to downstream of the unincorporated community of Twickenham, and generally north thereafter.〔 Rock Creek enters the river at the north end of Picture Gorge.〔 Bridge Creek passes through Mitchell, then north along the eastern edge of the Painted Hills Unit to meet the John Day downstream of Twickenham. Intermittent streams in the Clarno Unit empty into Pine Creek, which flows just beyond the south edge of the unit and enters the John Day upstream of the unincorporated community of Clarno.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「John Day Fossil Beds National Monument」の詳細全文を読む スポンサード リンク
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