Mission Valley Formation

Mission Valley Formation
Stratigraphic range: Paleogene
Type	Geologic formation
Underlies	Pomerado Conglomerate
Overlies	Stadium Conglomerate
Thickness	0–60 metres (0–197 ft)
Lithology
Primary	sandstone
Location
Region	San Diego County, California
Country	United States
Type section
Named for	Mission Valley, San Diego

The Mission Valley Formation is a marine sandstone geologic formation in the Mission Valley region of southwestern San Diego County, California. ^{[1] [2]}

Geology

The formation's sandstone characteristics are: soft and friable, light olive gray, fine to medium grained, and composed mostly of quartz and potassium feldspar. ^[1] The Mission Valley Formation thins from the west to the east, with a maximum thickness of 0–60 metres (0–197 ft). ^[1]

It overlies the Stadium Conglomerate formation and underlies the Pomerado Conglomerate formation. ^[1]

Fossil content

It preserves fossils dating back to the Paleogene period of the Cenozoic Era. ^[3] The formation's rocks can contain a molluscan fauna in the western and central exposures and a land-mammal fauna in the eastern exposures. ^[1]

Mammals

Eulipotyphlans

Eulipotyphlans reported from the Mission Valley Formation
Genus	Species	Presence	Material	Notes	Images
Proterixoides	P. davisi		Several calcaneums, astragali and a navicular. [4]

Ferae

Ferae reported from the Mission Valley Formation
Genus	Species	Presence	Material	Notes	Images
Ceruttia	C. sandiegoensis	"SDSNH locality 4888, State Road 125 North (Unit II, Mid Brown Siltstone)". [5]	SDSNH 92504 and SDSNH 92503. [5]	A carnivoraform.
cf. ' Miacis'	cf. 'M.' hookwayi	SDSNH locality 4715, State Route 125 Grossmont. [5]	SDSNH 84969 "right dentary fragment with p2, m1, and m2". [5]	A miacid.
Procynodictis	P. progressus	SDSNH locality 3870, Scripps Ranch North Site 70. [5]	"SDSNH 54413 (left dentary fragment with p2-m2); SDSNH 54414 (right dentary fragment with m1-2); SDSNH 54416 (left maxillary fragment with P4-M1)". [5]	A miacid.

Primatomorphs

Primatomorphs reported from the Mission Valley Formation
Genus	Species	Presence	Material	Notes	Images
Hemiacodon	H. sp.	V-72157. [6]	Isolated fragmentary teeth. [6]	An omomyid, most similar to H. gracilis.
?Macrotarsius	?M. sp.	V-72150 & V-73138. [6]	Isolated molars. [6]	An omomyid also known from the Friars Formation, closely similar to M. jepseni.
Microsyops	M. sp. cf. M. annectens	V-72158. [6]	Isolated & fragmentary molar (UCMP 101619). [6]	A microsyopid.
Notharctus	N. sp.	V-72157. [6]	Damaged isolated molar (UCMP 113256). [6]	A notharctine similar to N. robustior.
Omomys	O. powayensis	V-71180, V-72157 & V-72158. [6]	Teeth. [6]	An omomyid also known from the Friars Formation.
Pelycodus	P. sp.	V-73138. [6]	Maxillary fragment (UCMP 113210). [6]	A notharctine.
Uintasorex	U. montezumicus	V-71180, V-71211, V-72157, V-72158, V-72176, V-72177, V-72179, V-73138 & V-73139. [6]	Isolated teeth. [6]	A microsyopid also known from the Friars Formation.
Walshina	W. esmaraldensis	SDSNH localities 3426 and 4020. [7]	Teeth. [7]	An omomyid also known from the Sespe & Santiago formations.
Washakius	W. woodringi	V-71211, V-72157, V-72158, V-72176, V-72179 & V-73138. [6]	Teeth & jaw elements. [6]	An omomyid also known from the Friars Formation.

See also

• California portal

• Geology of San Diego County, California
• Paleogene Period in California
• List of fossiliferous stratigraphic units in California
• Paleontology in California

References

1. Kennedy, Michael P. (1975). Geology of the San Diego metropolitan area, California. California Division of Mines and Geology.
2. Geiconsultants.com: Geologic Formations of Western San Diego County ^{[ permanent dead link ]}, by Jeffrey D. Brown, R.G., C.E.G. − circa 1996.
3. Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database" . Retrieved 17 December 2021.
4. PENKROT, TONYA A.; ZACK, SHAWN P. (2016). "Tarsals of Sespedectinae (?Lipotyphla) from the Middle Eocene of Southern California, and the Affinities of Eocene 'Erinaceomorphs'" . Journal of Vertebrate Paleontology. 36 (6): e1212059. Bibcode:2016JVPal..36E2059P. doi:10.1080/02724634.2016.1212059. ISSN   0272-4634. JSTOR   44865966.
5. Tomiya, Susumu (2013-05-20). "New carnivoraforms (Mammalia) from the middle Eocene of California, USA, and comments on the taxonomic status of 'Miacis' gracilis". Palaeontologia Electronica. 16 (2): 1–14. doi: 10.26879/364 . ISSN   1094-8074.
6. Lillegraven, Jason A. (1980). "Primates from Later Eocene Rocks of Southern California" . Journal of Mammalogy. 61 (2): 181–204. doi:10.2307/1380040. ISSN   0022-2372. JSTOR   1380040.
7. López-Torres, Sergi; Silcox, Mary T.; Holroyd, Patricia A. (2018-09-22). "New omomyoids (Euprimates, Mammalia) from the late Uintan of southern California, USA, and the question of the extinction of the Paromomyidae (Plesiadapiformes, Primates)". Palaeontologia Electronica. 21 (3): 1–28. doi: 10.26879/756 . ISSN   1094-8074.

Further reading

• "General Plan Final Program EIR: 3.11 Paleontological Resources" (PDF). City of San Diego.