Dam Formation

Dam Formation
Stratigraphic range: Early Miocene ~22–18  Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
The location of the Dam formation in Qatar (dark and light blue dots)
Type	Geological formation
Sub-units	Al-Kharrara Member, Al-Nakhsh member, Abu Samrah member
Underlies	Dammam Formation
Overlies	Hofuf Formation
Lithology
Primary	Silicate, dolomite and calcite
Other	Celestine, chlorite, gypsum, kaolinite, muscovite, illite, palygorskite, and smectite [1]
Location
Country	Qatar, Saudi Arabia, UAE
Type section
Named by	Steineke and Kock (unpublished), Powers (in Saudi Arabia), Cavelier (in Qatar)
Year defined	1935 (unpublished), 1968 (Saudi Arabia), 1970 (Qatar)
Coordinates	26°21′42″N49°27′42″E / 26.36167°N 49.46167°E / 26.36167; 49.46167
Country	Qatar, Saudi Arabia, United Arab Emirates
Dam Formation (Saudi Arabia)

The Dam Formation is an Early Miocene formation located in southwestern Qatar, ^[2] Saudi Arabia and the UAE. ^[3]

Description

The formation was first described in a report in 1935 by Steineke and Kock. However, this report was unpublished. It was first described in published material by Powers in 1968 in Saudi Arabia, and by Cavelier in 1970 in Qatar. ^[3]

The formation in Saudi Arabia and the U.A.E. was deposited in a terrestrial environment, while the formation in Qatar was deposited in a marine habitat as evidenced by the multiple marine animals found in the formation. ^{[2] [3]}

Fossil content

Mammals from the Dam formation
Genus	Species	Material	Notes	Member	Images
Salwasiren	S. qataernsis [2]	ARC.2023.23.008, one associated skeleton including an incomplete cranium, mandible, left upper molar (M2), sternum, both scapulae and humeri, a partial vertebral column and ilium. ARC.2023.28.014, an incomplete left incisor [2]		Lower Al-Kharrara Member
Odontoceti	Indeterminate [2] [3]	A tooth [3] among other remains		Lower Al-Kharrara Member

Fishs from the Dam formation
Genus	Species	Material	Notes	Member	Images
Teleost	Indeterminate [2]			Lower Al-Kharrara Member
Carcharhiniformes	Indeterminate [2]
Physodon/ Scoliodon [3]	P./S.sp.
Aetobatus	A.arcuatus [3]		A species of Eagle ray
Diodon [3]	D.sp.		A species of porcupine fish

Reptiles from the Dam formation
Genus	Species	Material	Notes	Member	Images
Testudines	Indeterminate [2] [3]			Lower Al-Kharrara Member
Reptillia?	Indeterminate [3]			Lower/Middle Al-Kharrara Member

Molluscs from the Dam formation
Genus	Species	Material	Notes	Member	Images
Ostrea [3]	O.latimarginata		Bivalve	Lower & Middle Al-Kharrara Members
Pectinidae [3]	Indeterminate		Scallop
Anomia [3]	Indeterminate		Bivalve
Spondylus [3]
Avicula [3]
Clementia [3]	C.papayracea		"Impressions and molds"	Lower, Middle & Upper Al-Kharrara Members & Abu Samrah member
Chama [3]	C. gryphoides
Clausinella [3]	C.erisca		Bivalve
	C. persica
Hydrobiidae [3]	Indeterminate		A family of fresh to brackish water snails
Chlamys [3]	C.senatoria		Bivalve	Upper Al-Kharrara Member & Abu Samrah member
Fissurella [3]	Indeterminate		Gastropod
Natica [3]
Xenophora [3]
Turritella [3]
Cerithiidae [3]
Conus [3]
Bulla [3]
Hydrobia [3]			Gastropod "Very locally" found
Potamides [3]
Capsa [3]	C. lacunosa
	cf. C. fragilis
Tellina [3]	T. bipartita		Bivalve
Diplodonta [3]	D.cf. rotundata
Barbatia [3]	B. barbata		Bivalve
Anadara [3]	A.cf. turonica
Cardiocardita [3]	C.cf. monolifera
	C.aff. turonica
Solecurtus [3]	S. basteroti
Timoclea [3]	T. subspadicea
Musculus [3]	M.sp.		Bivalve
Eastonia [3]	Indeterminate
Panopea [3]			Gastropod
Tapes [3]			Bivalve
Mactra [3]
Lucina [3]
Cardium [3]
? Olivella [3]			Remains of "Internal molds"
Voluta [3]
Fasciolaria [3]
Cassis [3]
Cypraea [3]

Echinoderms from the Dam formation
Genus	Species	Material	Notes	Member	Images
Fibularia [3]	F. damensis		A Sand Dollar
Agassizia [3]	A. aff. persica		Sea urchin
Cidaris [3]	C.sp.	Spines

Bryozoans from the Dam formation
Genus	Species	Material	Notes	Member	Images
?Cupuladria [3]	C. gr.haidingeri

Crustacean remains have also been found in the formation ^[3]

References

1. "Al-Nakhsh Member, Dam Formation, Qatar". www.mindat.org. Retrieved 2026-01-13.
2. Pyenson, Nicholas D.; Sakal, Ferhan; LeBlanc, Jacques; Blundell, Jon; Klim, Katherine D.; Marshall, Christopher D.; Velez-Juarbe, Jorge; Wolfe, Katherine; Al-Naimi, Faisal (2025-12-10). "High abundance of Early Miocene sea cows from Qatar shows repeated evolution of seagrass ecosystem engineers in Eastern Tethys". PeerJ. 13 e20030. doi: 10.7717/peerj.20030 . ISSN   2167-8359. PMC   12701702 . PMID   41394419.
3. LeBlanc, Jacques (2021-10-22). "Stratigraphic Lexicon: A revised guide to the Cenozoic Surface Formations of Qatar, Middle East (excluding the islands)". Biosis: Biological Systems. 2 (4). doi:10.37819/biosis.001.04.0134. ISSN   2707-9783.