Carlile Shale

Carlile Shale
Stratigraphic range: Turonian ~
Rare exposure of the Fairport Chalk member of the Carlile Shale in southern Ellis County, Kansas
Type	Geological formation
Unit of	Colorado Group (lower); or Benton Formation
Sub-units	Juana Lopez (CO, NM) Codell Sandstone Blue Hill Shale Fairport Chalk
Underlies	Niobrara Formation
Overlies	Greenhorn Limestone
Thickness	170–230 feet (52–70 m)
Lithology
Primary	Shale, chalky to carbonaceous
Other	Limestone Sandstone Siltstone Septarians Bentonite
Location
Coordinates	38.376°N 104.979°W / 38.376; -104.979
Region	Mid-continental
Country	United States
Type section
Named for	Carlile Spring and Carlile Station, 21 mi west of Pueblo, Colorado
Named by	Gilbert
Year defined	1896
Carlile Shale (the United States) Carlile Shale (Colorado)

The Carlile Shale is a Turonian age Upper/Late Cretaceous series shale geologic formation in the central-western United States, including in the Great Plains region of Colorado, Kansas, Nebraska, New Mexico, North Dakota, South Dakota, and Wyoming.

It is composed of marine deposits of the generally retreating phase (hemi-cycle) of the Greenhorn cycle of the Western Interior Seaway, which followed the advancing phase of the same cycle that formed the underlying Graneros Shale and Greenhorn Formation. As such, the lithology progresses from open ocean chalky shale (with thin limestones) to increasing carbonaceous shale to near-shore sandstone. There is a discontinuity between the top of the Carlile and the Niobrara sequence.

Viewing and access

Auto touring in Kansas

West from mile 195, Interstate 70 leaves the level bench on the Fencepost limestone for low, broad residual hills of Carlile Shale. These low hills are mostly the Fairport Chalk member, its thin limestone beds making it more resistant than the Blue Hill Shale member. In the distance to the northwest, the Fort Hays Limestone escarpment is visible, the slopes of which are grass-covered Blue Hill Shale.

Taking the Yocemento Avenue Exit 153 south, Yocemento lies at the base of the Fort Hays bluffs. Between Yocemento and Ellis, Old Hwy 40 passes over grass-covered slump blocks of Blue Hill Shale. The Codell Sandstone member is not present in this part of the county. 14 miles south of Ellis, on Monroe St./Ellis Ave., a broad slope of blue-gray Blue Hill Shale is exposed; the soil in this area "blew out" during the Dust Bowl; many orange-tinted septarian boulders may be seen from the road.

Fossils

Upper Turonian series Plesiosaur remains are among the fossils that have been recovered from the strata of its Blue Hill Shale Member in Kansas. The Carlile in eastern South Dakota contains shark teeth, fossil wood and leaves, and ammonites.

History of investigation

The Carlile Shale was first named by Grove Karl Gilbert for exposures at Carlile Spring, located about 21 miles (34 km) west of Pueblo, Colorado. He described it as a medium gray shale, capped with limestone or sandstone, and assigned it to the Benton Group.

Gallery

• 
  The lower 25 feet (7.6 m) of the Fairport Chalk member in southern Ellis County, Kansas.
• 
  1867, bluffs west of Hays, behind the seated soldiers is pre-settlement digging in the Blue Hill Shale.
• 
  The bare Blue Hill Shale slopes at Yocemento as they appeared in 1873.

See also

• Volcanic mineralization of the Greenhorn cycle:
  • Bentonite, sedimentary volcanic ash (named for the original Graneros/Greenhorn/Carlile classification), generally showing some weathered iron stain in the Colorado Group
  • Pyrite, precipitation of volcanic sulfuric acid with oceanic iron as FeS₂
  • Limonite, pyrite in limestone weathered to HFeO₂ (rust stain or yellow ochre)
  • Selenite, CaSO4 associated with Bentonite seams and ochre

• Plesiosaur stratigraphic distribution