Harkless Formation

Harkless Formation
Stratigraphic range: Lower Cambrian PreꞒ Ꞓ O S D C P T J K Pg N [1]
Type	Formation
Underlies	Saline Valley Formation
Overlies	Poleta Formation
Thickness	0–3,600 ft (0–1,097 m) [1]
Lithology
Primary	Siltstone
Other	Quartzite, Limestone
Location
Region	Nevada and California
Country	United States
Type section
Named for	Harkless Flat

The Harkless Formation is a geologic formation in Nevada and California. It preserves fossils dating back to the Cambrian period. ^{[1] [2]}

It is named from exposures on a divide south of Harkless Flat in the southern half of the Waucoba Mountain 15-min quadrangle in the Inyo Mountains of central eastern California. ^[3]

Geology

The Harkless Formation is mainly composed of siltstones, with many layers of fine to medium-grained quartzites, with limestone within the lower parts of the formation. ^[1]

Paleobiota

The Harkless Formation contains a number of sponge spicules, hyoliths, brachiopods, and other small shelly fauna. ^{[4] [2]}

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Lophotrochozoa

Genus	Species	Notes	Images
Hyolithellus [4] [2]	H. insolitus	Lophotrochozoan hyolith. May possibly be an annelid. [5]
Kyrshabaktella [4]	Kyrshabaktella sp.	Linguliform brachiopod.
Eothele (?) [4]	E. spurri (?)	Acrotheloid brachiopod.
Hadrotreta (?) [4]	H. primaea (?)	Acrotheloid brachiopod.

Cnidaria

Genus	Species	Notes	Images
Sphenothallus [4] [2]	Sphenothallus sp.	Cnidarian conulariid.

Echinodermata

Genus	Species	Notes	Images
Echinoderm Ossicles [4] [2]	???	Calcareous element that makes up the endoskeleton of echinoderms.

Porifera (Sponges)

Genus	Species	Notes	Images
Sponge spicule type 1 [4]	???	Sponge skeleton, with four rays.
Sponge spicule type 2 [4]	???	Sponge skeleton, with six short rays.

See also

• Earth sciences portal
• United States portal
• Paleontology portal

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

References

1. Stewart, J. H. "Upper Precambrian and Lower Cambrian Strata, in the Southern Great Basin California and Nevada" (PDF). U.S. Geological Survery. Geological Survey Professional.
2. Wotte, Thomas; Sundberg, Frederick A. (September 2017). "Small shelly fossils from the Montezuman–Delamaran of the Great Basin in Nevada and California". Journal of Paleontology. 91 (5): 883–901. doi:10.1017/jpa.2017.8.
3. "Geologic Unit: Harkless". National Geologic Map Database. U.S. Geological Survey. Retrieved 23 April 2022.
4. Skovsted, Christian B.; Holmer, Lars E. (December 2006). "The Lower Cambrian brachiopod Kyrshabaktella and associated shelly fossils from the Harkless Formation, southern Nevada". GFF. 128 (4): 327–337. doi:10.1080/11035890601284327.
5. Skovsted, Christian B.; Peel, John S. (January 2011). "Hyolithellus in life position from the Lower Cambrian of North Greenland". Journal of Paleontology. 85 (1): 37–47. doi:10.1666/10-065.1.

• Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 25 March 2022. Retrieved 17 December 2021.