Age

Formation

Type of rocks

Thickness (m)

Eocene

Chalk Marl B4/5

Chalk marl and chert

Up to 150

Cretaceous-Tertiary

Bituminous Marl B3

Bituminous Marl

Only in small outcrops

Campanian Maastrichtian

Um Ghudran Silicified Limestone B1/2

Silicified limestone overlain by chert beds

Around 70 m

Turonian-Santonian

Massive Limestone A7

Massive sandy limestone

55 m

Cenomanian

Na’ur A1/2, Fuheis A3 Hummar A4, Shueib A5/6

Alternating beds of limestone, dolomite, marly limestone, dolomitic limestone, sandstone, marl and some gypsum layers and evaporate residues

Around 300 m

Deep sandstone aquifer system

Lower Cretaceous-Precambrian

Coarse, medium and fine-grained sandstone

1450 - 1600 m