- Hell Creek Formation
The Hell Creek Formation is an intensely-studied division of
Upper Cretaceous to lowerPaleocene rocks in North America, named for exposures studied along Hell Creek, nearJordan, Montana .The Hell Creek Formation occurs in badlands of eastern
Montana and portions ofNorth Dakota ,South Dakota , andWyoming . In Montana, the Hell Creek Formation overlies theFox Hills Formation and is the uppermost formation of the Cretaceous period. "Pompey's Pillar" at thePompeys Pillar National Monument is a small isolated section of the Hell Creek Formation.It is a series of fresh and brackish-water
clays ,mudstone s, andsandstones deposited during theMaastrichtian , the last part of theCretaceous period , byfluvial activity in fluctuating river channels and deltas and very occasional peaty swamp deposits along the low-lying easterncontinental margin fronting the late CretaceousWestern Interior Seaway . The climate was mild, and the presence ofcrocodylians suggests a sub-tropical climate, with no prolonged annual cold. The famousiridium -enrichedK-T boundary , which separates the Cretaceous from theCenozoic , occurs as a discontinuous but distinct thin marker bedding within the Formation, near its uppermost strata.Commercial excavations bring Hell Creek fossils onto the market, usually dinosaur teeth,
crocodylian osteoderm fragments, and dermal plates of fossilgar s. A representative selection of Hell creek fossils can be seen at theMuseum of the Rockies , inBozeman, Montana .Fossils
The formation has produced impressive assemblages of
invertebrates ,plants ,mammals ,fish ,reptiles , andamphibians . The most completeHadrosaurid dinosaur ever found was retrieved in 2000 from the Hell Creek Formation and widely publicised in a "National Geographic" documentary aired in December 2007. A fewbird andpterosaur fossils have also been found. Teeth ofshark s and rays are sometimes found in the riverine Hell Creek Formation, suggesting that some of these taxa were tolerant of fresh water then as now.Birds and other theropods
Pterosaurs
ee also
*
List of fossil sites "(with link directory)"
*List of dinosaur-bearing rock formations References
External links
* [http://www.dinosauria.com/jdp/misc/hellcreek.html Cretaceous Hell Creek Faunal Facies] provides a faunal list.
* [http://www.scn.org/~bh162/index.html Phillip Bigelow, "Hell Creek life: Fossil Flora & Fauna, a Paleoecosystem"]
* [http://paleodb.org/cgi-bin/bridge.pl?action=displayCollectionDetails&collection_no=12977 Paleobiology Database: MPM locality 3850 (Hell Creek Formation): Maastrichtian, Montana]
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