Baska Formation
Eocene
Sulaiman Basin
Part of Ghazij Group, Chamalang (=Ghazij) Group
Paleogene in the time scale →Cited in 7 sources Last reviewed Aug 10, 2026
- Rank
- formation
- Status
- Published
- Age
- Cenozoic · Paleogene · Early EoceneEocene
- Named by
- Hemphill et al. (1973)
- Type locality
- 2 km east-northeast of Baska village31.4833°N, 70.1333°E
- Thickness
- 100m
- Lithology
- Green to grey shale and claystone interbedded with alabaster (gypsum), gypsiferous limestone and marl.
- Synonyms
- Not recorded
A gypsum-bearing Early Eocene shale, the top of the Ghazij Group, marking a restricted, salty phase.
Proposed by Hemphill and Kidwai (1973) to replace Eames' (1952) descriptive term 'shale with alabaster', with its type section near Baska village, the Baska Formation consists of gypsum, shale, limestone, marl and rare siltstone and is roughly 30–100 m thick. Its lower contact with the Drug Formation and upper contact with the Habib Rahi Formation are conformable. Fossiliferous rubbly limestone beds have yielded foraminifera (e.g. Lockhartia hunti, Dictyoconoides vredenburgi), bivalves and gastropods with an Early Eocene aspect (Iqbal, 1969).
Fossils
Contacts
Band colour = period; texture = dominant rock type. Lines between bands mark the contact type. 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
- Basin
- Sulaiman Basin
- Region
- Not recorded
- Depositional environment
- restricted marine, evaporitic
- Coordinates
- 31.4833°N, 70.1333°E
Correlation
Not recorded. Compare this unit against other basins on the correlation panel →
Economic significance
Contains alabaster (gypsum) beds.
Remarks
The uppermost, gypsum-bearing unit of the Ghazij Group in the Sulaiman Range, recording restricted, evaporitic conditions at the close of Ghazij deposition.
Sources (7)
- Malkani, M.S. & Mahmood, Z. (2017). Stratigraphy of Pakistan. Geological Survey of Pakistan, Memoir Vol. 24.
- Kazmi, A.H. & Jan, M.Q. (1997). Geology and Tectonics of Pakistan. Graphic Publishers, Karachi.
- 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.
- Jones, R.W. (1997). Aspects of the Cenozoic stratigraphy of the Northern Sulaiman Ranges, Pakistan. Journal of Micropalaeontology, 16(1), 51-58.
- Kazmi, A.H. & Abbasi, I.A. (2008). Stratigraphy and Historical Geology of Pakistan. Department & National Centre of Excellence in Geology, University of Peshawar, Peshawar. 524 pp. ISBN 978-969-9119.
- Hemphill, W.R. & Kidwai, A.H. (1973). Stratigraphy of the Bannu and Dera Ismail Khan Areas, Pakistan. U.S. Geological Survey Professional Paper 716-B (Geological Investigations in Pakistan), 36 p.
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.
Cite this unit
Qudsi, L. (2026). Baska Formation. In Pakistan Stratigraphy Dataset [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21363991
@misc{stratigraphypk_baskaformation,
author = {Qudsi, Lareb},
title = {{Baska 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/baska-formation (accessed August 30, 2026).
To cite the unit's original definition instead, see: Hemphill et al. (1973).
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