Eagle Sandstone

The Eagle Sandstone, originally the Eagle Formation, is a geological formation in Montana whose strata date back to the Late Cretaceous. It is a light to brownish gray to pale yellow-orange, fine-grained sandstone. It contains areas of crossbedding and local shale members. It contains large (up to 15 feet in diameter) sandy calcareous concretions. Its thickness varies from 100 to 350 feet due to the lens nature of the individual sandstone layers and local interbedded sandy shale layers.^[1]

Eagle Sandstone
Stratigraphic range: Late Cretaceous
Eagle Sandstone above Billings, MT
Type	Geological formation
Underlies	Claggett Shale, Judith River Formation
Overlies	Telegraph Creek Formation, Niobrara Shale
Thickness	100 to 350 feet
Lithology
Primary	Sandstone
Other	Sandy shale
Location
Region	Montana

Dinosaur fossils have been recovered from the formation.^[2]

Weathering and erosion of the formation has created natural arches, hoodoos and other picturesque features of the Upper Missouri River Breaks National Monument.^[3]

Vertebrate paleofauna

• "Ornithomimus" grandis - Pes.^[4]

See also

• Earth sciences portal
• Paleontology portal
• Dinosaurs portal

• List of dinosaur-bearing rock formations
• List of fossiliferous stratigraphic units in Montana
• Paleontology in Montana