Canutillo Formation

Canutillo Formation
Stratigraphic range: Middle Devonian
Type	Formation
Underlies	Percha Formation
Overlies	Fusselman Formation
Thickness	15 feet (4.6 m)
Lithology
Primary	Siltstone
Other	Shale
Location
Coordinates	31.92°N 106.50°W / 31.92; -106.50
Region	Texas
Country	United States
Type section
Named for	Canutillo, Texas
Named by	L.A. Nelson
Year defined	1940
Canutillo Formation (the United States) Show map of the United States Canutillo Formation (Texas) Show map of Texas

The Canutillo Formation is a geologic formation that is exposed in the Franklin Mountains near El Paso, Texas. The formation is Middle Devonian in age.[1][2]

Description

The Canutillo Formation consists of about 15 feet (4.6 m) of soft gray siltstone. It is unconformably overlain by the Percha Formation. The Canutillo Formation likely correlates with the Onate Formation.[1]

Fossils

The formation is fossiliferous, but few fossils are time diagnostic. Fossils include abundant Leiorhynchus and other brachiopods and a few pelecypods.[1]

History of investigation

The formation was first described in his dissertation by L.A. Nelson in 1937 for outcrops in the Franklin Mountains. Nelson assigned all beds between the Silurian Fusselman Formation and the Mississippian Helms Formation to the Canutillo.[3] Nelson formally published the definition in 1940 and extended the outcrop range to the Hueco Mountains.[4] In 1945, F.V. Stevenson restricted the formation to the Franklin Mountains.[5] In 1949, Lowell R. Laudon and Arthur L. Bowshwer restricted the formation to a sequence of just 15 feet (4.6 m) of soft gray siltstone.[1]

See also

• List of fossiliferous stratigraphic units in Texas
• Paleontology in Texas

Footnotes

1. Laudon, Lowell R.; Bowsher, Arthur L. (1949). "Mississippian formations of southwestern New Mexico". Geological Society of America Bulletin. 60 (1): 1. doi:10.1130/0016-7606(1949)60[1:MFOSNM]2.0.CO;2.
2. Ludington, Steve; Hanna, W.F.; Turner, R.L.; Jeske, R.E. (1988). "Mineral resources of the Organ Mountains Wilderness Study Area, Dona Ana County, New Mexico". U.S. Geological Survey Bulletin. 1735-D. doi:10.3133/b1735D. hdl:2027/osu.32435022084842.
3. Nelson, L.A. (1937). "Gastropoda from the Pennsylvanian (Magdalena) of the Franklin Mountains of west Texas [abstract of thesis]". Colorado University Studies. 25 (1): 89–91.
4. Nelson, L.A. (1940). "Paleozoic Stratigraphy of Franklin Mountains, West Texas". AAPG Bulletin. 24 (1): 157–172. doi:10.1306/3D93319A-16B1-11D7-8645000102C1865D.
5. Stevenson, Frank V. (July 1945). "Devonian of New Mexico". The Journal of Geology. 53 (4): 217–245. doi:10.1086/625283.