Niobrara Chalk

E683719

chalk formation geologic formation sedimentary rock unit

Niobrara Chalk is a Late Cretaceous marine sedimentary rock formation of soft, fossil-rich chalk and shale that is especially noted for its abundant marine reptile and fish fossils across the central United States.

Try in SPARQL Jump to: Surface forms Disambiguation Statements Elicitation Referenced by

All labels observed (2)

Label	Occurrences
Niobrara Formation	2
Niobrara Chalk canonical	1

How this entity was disambiguated

This entity first appeared as the object of triple T7721191 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.

NED1 Entity disambiguation (via context triple) gpt-5-mini-2025-08-07

Target entity: Niobrara Chalk
Context triple: [Gove County, Kansas, hasGeology, Niobrara Chalk]

A. Morrison Formation
The Morrison Formation is a vast Late Jurassic sedimentary rock formation in the western United States renowned for its exceptionally rich assemblage of dinosaur fossils, including iconic sauropods and theropods.
B. Dakota Formation
The Dakota Formation is a widespread Cretaceous sedimentary rock unit in North America, noted for its sandstone deposits that record the advance of the Western Interior Seaway and preserve abundant plant and dinosaur fossils.
C. Claron Formation
The Claron Formation is a geologic rock unit of colorful limestones and mudstones best known for forming the striking hoodoos and cliffs of Bryce Canyon and other parts of the Paunsaugunt Plateau in southern Utah.
D. Boone Formation
The Boone Formation is a Mississippian-age carbonate rock unit of cherty limestones and dolomites widely exposed across parts of the Ozark region in the central United States.
E. Hell Creek Formation
The Hell Creek Formation is a famous Late Cretaceous rock unit in North America renowned for its exceptionally rich dinosaur fossils, including iconic specimens like Tyrannosaurus rex and Triceratops.
F. None of above. chosen
G. Unsure - the case is ambiguous/there is not enough information to decide.

NED2 Entity disambiguation (via description) gpt-5-mini-2025-08-07

Target entity: Niobrara Chalk
Target entity description: Niobrara Chalk is a Late Cretaceous marine sedimentary rock formation of soft, fossil-rich chalk and shale that is especially noted for its abundant marine reptile and fish fossils across the central United States.

A. Morrison Formation
The Morrison Formation is a vast Late Jurassic sedimentary rock formation in the western United States renowned for its exceptionally rich assemblage of dinosaur fossils, including iconic sauropods and theropods.
B. Dakota Formation
The Dakota Formation is a widespread Cretaceous sedimentary rock unit in North America, noted for its sandstone deposits that record the advance of the Western Interior Seaway and preserve abundant plant and dinosaur fossils.
C. Claron Formation
The Claron Formation is a geologic rock unit of colorful limestones and mudstones best known for forming the striking hoodoos and cliffs of Bryce Canyon and other parts of the Paunsaugunt Plateau in southern Utah.
D. Boone Formation
The Boone Formation is a Mississippian-age carbonate rock unit of cherty limestones and dolomites widely exposed across parts of the Ozark region in the central United States.
E. Hell Creek Formation
The Hell Creek Formation is a famous Late Cretaceous rock unit in North America renowned for its exceptionally rich dinosaur fossils, including iconic specimens like Tyrannosaurus rex and Triceratops.
F. None of above. chosen

Statements (49)

Predicate	Object
instanceOf	chalk formation ⓘ geologic formation ⓘ sedimentary rock unit ⓘ
age	Campanian ⓘ Coniacian ⓘ Santonian ⓘ
color	light-colored ⓘ
contains	coccoliths ⓘ foraminifera ⓘ microfossils ⓘ
country	United States of America ⓘ surface form: United States
depositionalEnvironment	Western Interior Seaway NERFINISHED ⓘ epicontinental sea ⓘ
discoveredBy	early American geologists ⓘ
economicUse	source of limestone ⓘ
fossilContent	ammonites ⓘ birds ⓘ invertebrates ⓘ marine turtles ⓘ mosasaurs ⓘ plesiosaurs ⓘ pterosaurs ⓘ teleost fish ⓘ
fossilPreservation	exceptional vertebrate fossils ⓘ
geologicPeriod	Late Cretaceous NERFINISHED ⓘ
knownFor	well-preserved fish skeletons ⓘ well-preserved mosasaur skeletons ⓘ well-preserved pterosaur fossils ⓘ
lithology	chalk ⓘ shale ⓘ
namedFor	Niobrara River NERFINISHED ⓘ
notableFor	abundant fish fossils ⓘ abundant marine reptile fossils ⓘ
outcropsIn	Colorado NERFINISHED ⓘ Kansas NERFINISHED ⓘ Nebraska NERFINISHED ⓘ New Mexico NERFINISHED ⓘ South Dakota NERFINISHED ⓘ Wyoming NERFINISHED ⓘ
overlies	Carlile Shale NERFINISHED ⓘ
paleontologicalSignificance	important vertebrate fossil lagerstätte ⓘ
primaryMineral	calcite ⓘ
region	central United States ⓘ
rockType	marine sedimentary rock ⓘ
stratigraphicUnitOf	Western Interior Seaway succession ⓘ
subunit	Fort Hays Limestone Member NERFINISHED ⓘ Smoky Hill Chalk Member NERFINISHED ⓘ
texture	soft ⓘ
underlies	Pierre Shale NERFINISHED ⓘ

How these facts were elicited

Referenced by (3)

Full triples — surface form annotated when it differs from this entity's canonical label.

Gove County, Kansas → hasGeology → Niobrara Chalk ⓘ

Pierre Shale → overlies → Niobrara Chalk ⓘ

this entity surface form: Niobrara Formation

Western Interior Basin → includesFormation → Niobrara Chalk ⓘ