Cenozoic • Paleogene In GSP lexicon

Chashmai Formation

Eocene

Cited in 5 sources Last reviewed Jul 16, 2026

Unit summary

Rank: Not recorded
Status: Published
Age: Cenozoic · Paleogene · Early–Middle EoceneEocene
Named by: Not recorded
Type locality: Chashmai, Kohat
Thickness: 50-150 m
Lithology: Clastic facies — sandstone and shale — of the Eocene Kohat succession.
Synonyms: Not recorded

The sandy-and-shaly western version of the Eocene Kohat rocks — the same age as the Shekhan limestone but made of clastic sediment.

Named after Chashmai area in Kohat. Marginal marine to continental sequence. Part of the Panoba Group.

Fossils

Sparse fauna

Contacts

In the Kohat Basin column

LimestoneShale / mudSandstoneFossils recordedConformableContact not recorded

Band colour = period; texture = dominant rock type. Lines between bands mark the contact type; dotted = no contact recorded in the sources (not a claim of conformity). True scale makes height ∝ recorded thickness; hatched = thickness not recorded. Ages approximate, for ordering.

This unit (highlighted) within its province column; faded ends continue above and below. Line style marks the contact type.

Distribution & setting

Kohat Basin

Basin: Not recorded
Region: Not recorded
Depositional environment: shallow marine
Coordinates: Not recorded

Correlation

Not recorded. Compare this unit against other basins on the correlation panel →

Economic significance

Not recorded

Remarks

The western clastic (siliciclastic) lateral facies of the Eocene Kohat succession, equivalent eastward to the carbonate Shekhan Formation and, in the centre and south, to the Bahadar Khel Salt–Jatta Gypsum evaporites.

Research notes (2)

Field-by-field findings drawn from the cited literature. Every statement is traced to a registered source — follow a citation for the full reference.

Name & nomenclature (2)

Distinct from the separate Cretaceous 'Chashmai Kharsai Formation' of the Kurram/Waziristan area; this Kohat-Potwar entry is the Eocene clastic facies.

Khan, S., Rashid, M.U. & Haider, N. (2019)
Removed the stray synonym 'Chashmai Kharsai': that is a separate Early Cretaceous belemnite shale of North Waziristan (Ahmed et al. 2000), now recorded as the distinct Chashmai Kharsai Formation. The Eocene Chashmai Formation is unrelated.

Shah, S.M.I. (2009)

Sources (4)

Malkani, M.S. & Mahmood, Z. (2017). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 24.
Khan et al. (2019). Foraminiferal studies of the Eocene Shekhan Formation, Panoba section, Kohat, northern Pakistan: implications for biostratigraphy and palaeoenvironments. International Journal of Hydrology (MedCrave).
Indian Plate Lexicon (indplex.geolex.org), Geological Society of India and international compilation.
Shah, S.M.I. (2009). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 22.

Reviewer confidence: high

Every fact on this page is source-cited. This entry is part of the peer-archived Pakistan Stratigraphy Dataset (doi.org/10.5281/zenodo.21363991, CC‑BY‑4.0).

Lexicon status: Name attested in the Shah (1977/2009) Geological Survey of Pakistan compilation — the national stratigraphic lexicon. This records where the name is documented; it is not an endorsement of the unit’s definition, age or figures.

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Cite this unit

APA

Qudsi, L. (2026). Chashmai Formation. In Pakistan Stratigraphy Dataset [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21363991

BibTeX

@misc{stratigraphypk_chashmaiformation,
  author    = {Qudsi, Lareb},
  title     = {{Chashmai Formation} --- Pakistan Stratigraphy Dataset},
  year      = {2026},
  publisher = {Zenodo},
  doi       = {10.5281/zenodo.21363991},
  url       = {https://doi.org/10.5281/zenodo.21363991}
}

Archived dataset: doi.org/10.5281/zenodo.21363991 (CC‑BY‑4.0) · Direct link to this entry: https://stratigraphy.pk/formation/chashmai-formation (accessed October 29, 2026).

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