Al Hammah Formation

Al Hammah Fm

Period:

Quaternary

Age Interval:

Middle Pleistocene (Chibanian)

Province:
Cyrenaica Basin

Type Locality and Naming

Al Hammah Fm is located along the coastal margins of the Cyrenaica Basin in northeast Libya.

Synonym:

References: Shaltami, O.R., et al. (2020), and Google Gemina (Aug’26)

Lithology and Thickness

“The formation is dominantly composed of aeolian calcarenites (wind-blown, carbonate-rich sandstones) and consolidated oolitic/bioclastic grainstones. The framework grains consist heavily of reworked marine bioclasts (such as fragments of foraminifera, mollusks, and echinoids) that were swept onshore from exposed beaches during sea-level drops. It is notable for containing prominent, heavily reworked older fossils—such as Nummulites derived from the nearby eroded Eocene Dernah Fm. It exhibits distinct large-scale cross-bedding, a hallmark structural feature of ancient coastal sand dunes.” (Google Gemini overview)

Lithology Pattern:

Sandy limestone

Relationships and Distribution

Lower contact

Unconformable onto the Tansulukh Fm (Shaltami et al. (2020)). Both of these aeolian packages, the Al Hammah Fm and the “overlying to transitional Al Haniyah Fm are distinct from the purely marine calcarenites of the Tansulukh Fm (Google Gemini overview)

Upper contact

Unconformable below the similar aeolian facies of the Al Haniyah Fm (Shaltami et al. (2020))

Regional extent

Mainly the coastal margins of the Cyrenaica Basin. “Onshore winds transported loose, marine-derived carbonate sands inland, organizing them into expansive coastal dune ridges along the northern flank of the Al Jabal al Akhdar uplift.” (Google Gemini overview)

GeoJSON

{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[24.38,28.97],[24.44,29.45],[23.6,29.81],[21.28,29.89],[20.27,32.06],[20.25,33.14],[20.67,33],[23.31,33.18],[24.38,32.55],[24.99,32.54],[25.2,31.39],[26.18,29.37],[24.38,28.97]]]}}

Fossils

reworked bioclasts.

Age

“Ionian” according to Shaltami et al. (2020), which is Chibanian in the international Pleistocene stage terminology. [For graphic purposes, the extent of the upper and lower unconformities, which are equivalent to nearly the same time span of the known preserved deposits, have been omitted here.]

Age Span:

Beginning stage:

Chibanian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

0.77

Ending stage:

Chibanian

Fraction up in the ending stage:

1.0

Ending date (Ma):

0.13

Depositional setting

Coastal dunes

Depositional pattern:

Additional Information

Compiler:

Shaltami, O.R., et al. (2020). Petroleum system of the Cyrenaica Basin – A review. In: 1^st International Symposium on Geosciences (ISG2020), 21th March 2020, Proceeding Book: published by BR Petrobras. P. 64-71.

Tawadros, E.E. (2011). Geology of North Africa. CRC Press (Taylor & Francis Group), 931 pp.

Google Gemini (Aug 2026) – assembled synthesis of Cyrenaica Basin units from various web-accessible publications.

El Oshebi, F.M., Fares, F.F. (2026). Stratigraphy, facies, and depositional environments of the Eocene sequence in the Ras Al Hilal area, Cyrenaica, Libya. Arabian Jour. Geosciences, 19:79. https://doi.org/10.1007/s12517-026-12488-2.

El-Hawat, A.S., Abdulsamad, E.O. (2004) Geology and Archeology of Cyrenaica, Northeastern Libya. Field trip guide B01, 32^nd International Geological Congress. 36 pp.