A regional unconformity at the Danian–Selandian (D/S) boundary is recorded in Western Desert, Egypt,
based upon field study, biostratigraphic analyses and paleoenvironmental parameters. This unconformity
is marked by the absence of the topmost part of planktonic foraminifera Igorina albeari/Globanomalina
pseudomenardii (P3b) Subzone and the uppermost part of the equivalent calcareous nannofossil Ellipsolithus
macelus NP4 Zone (NTp8A-B Subzones) in all the sections studied. Furthermore, benthic foraminiferal

The gastropod fauna of the Upper Cretaceous Aruma Formation in central Saudi Arabia comprises fifteen
species belonging to fifteen genera, fourteen families, and five clades. The species are not abundant at any
individual stratigraphic level but are equally and irregularly scattered in the formation. The studied species
come mainly from the Hajajah Member of Upper Cretaceous Aruma Formation in central Saudi Arabia.
Calliomphalus orientalis (Douvillé, 1916); Coelobolma corbarica Cossmann, 1918; Turritella (Torquesia)

Bryozoan nodules, coralline algae, scleractinian corals and oysters form an important organic
buildup, 1.2–4.5 m thick in the Langhian-Serravaliann sediments of Egypt. Based on type, shape
and size of the substrate, bryozoan nodules take tree-like and globular morphologies. Tree-like specimens
reach 10 cm in maximum height and 3 cm in diameter, while Globular ones attain 9 cm in maximum
diameter. Most tree-like nodules are perforated with wide or narrow pores, few are

Seventy-five bryozoan species were picked from shallow bottom sediments (0–33m depths) at five sites in the northern Red
Sea: El Fanader, Hurghada Harbour, Makkadi Bay, Al Qweh Lagoon and El-Humrawen. Crisia specimens (Cyclostomata)
are common and exhibit different variations. Six species were recognised among the specimens collected: Crisia eburnea
(Linnaeus), Crisia elongata (Milne-Edwards), Crisia hornesi Reuss, Crisia sertularoides (Audouin), Crisia tenuis

In order to assess arsenic on the Tarut coast, Saudi Arabian Gulf, 38 sediment samples, 26 seawater
samples and 40 gastropod and bivalve specimens were collected for analyses by Inductively Coupled
Plasma-Mass Spectrometer. The Enrichment Factor (EF), the Geoaccumulation Index (Igeo) and the
Contamination Factor (CF) indicated that coastal sediments of Tarut Island are severely enriched, strongly
polluted and very highly contaminated with arsenic as a result of anthropogenic inputs. Comparison with