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The Dinosaur Park Formation is the uppermost member of the Belly River Group (also known as the Judith River Group), a major geologic unit in southern Alberta. It was laid down during the Campanian stage of the Late Cretaceous epoch between 76.6 and 74.8 million years ago.〔〔 It was deposited in alluvial and coastal plain environments, and it is bounded by the nonmarine Oldman Formation below it and the marine Bearpaw Formation above it.〔Eberth, D.A. 2005. The geology. In: Currie, P.J., and Koppelhus, E.B. (eds), Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press: Bloomington and Indianapolis,p.54-82. ISBN 0-253-34595-2.〕 The Dinosaur Park Formation contains dense concentrations of dinosaur skeletons, both articulated and disarticulated, which are often found with preserved remains of soft tissues. Remains of other animals such as fish, turtles, and crocodilians, as well as plant remains, are also abundant.〔Currie, P.J., and Koppelhus, E.B. (eds), Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press: Bloomington and Indianapolis, p. 277-291. ISBN 0-253-34595-2.〕 The formation has been named after Dinosaur Provincial Park, a UNESCO World Heritage Site where the formation is well exposed in the badlands that flank the Red Deer River.〔 ==Geological setting== The Dinosaur Park Formation is composed of sediments that were derived from the erosion of the mountains to the west. It was deposited on an alluvial to coastal plain by river systems that flowed eastward and southeastward to the Bearpaw Sea, a large inland sea that was part of the Western Interior Seaway. That sea gradually inundated the adjacent coastal plain, depositing the marine shales of the Bearpaw Formation on top of the Dinosaur Park Formation.〔 The Dinosaur Park Formation is about thick at Dinosaur Park. The lower portion of the formation was laid down in fluvial channel environments and consists primarily of fine- to medium-grained, crossbedded sandstones. The upper portion, which was deposited in overbank and floodplain environments, consists primarily of massive to laminated, organic-rich mudstones with abundant root traces, and thin beds of bentonite. The Lethbridge Coal Zone, which consists of several seams of low-rank coal interbedded with mudstones and siltstones, marks the top of the formation.〔 The sediments of the Dinosaur Park Formation are similar to those of the underlying Oldman Formation and they were originally included in that formation. The two formations are separated by a regional disconformity, however, and are distinguished by petrographic and sedimentologic differences. In addition, articulated skeletal remains and bonebeds are rare in the Oldman Formation but abundant in the Dinosaur Park Formation.〔〔 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「Dinosaur Park Formation」の詳細全文を読む スポンサード リンク
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