The Carboniferous rocks of northern Egypt are mainly in the subsurface; surface exposures are very limited. From the data available, six stratigraphic maps were constructed to show the thickness variations, facies changes, and paleogeology. Thickness maxima are in two main trends: (1) a narrow, linear, NW-SE basin coinciding with the Gulf of Suez and (2) a broad, NE-SW basin (with a thinner section) in the Western Desert. The basins are separated by a northward-extending "basement complex" mass on which no Carboniferous sedimentary rocks are present. Both basins seem to open toward the mouth of the Nile delta and the western part of Sinai.

Lithologically, the Carboniferous consists mainly of sandstone with minor limestone-shale intercalations. The shale and carbonate generally increase in amount northward. Northern Sinai has a more carbonate-rich facies than does the northern part of the Western Desert. Though the limestones are marine, the sandstones were deposited in environments ranging from marine to continental.

The lithologic characteristics and the thickness of the Carboniferous System were affected both by the tectonic framework of sedimentation and by subsequent geologic events. A large "basement complex" mass separated the eastern tectonically active embayment along the Gulf of Suez from the tectonically more stable Western Desert. The northern shelf region, which generally subsided during Carboniferous sedimentation, constituted the northernmost part of Egypt. The Gulf of Suez embayment therefore is inferred to have formed as early as the Carboniferous. Later structural evolution and denudation in places reduced the thickness of the Carboniferous section.

Petroleum is found in the Carboniferous strata of some fields in the Gulf of Suez province. Source rocks probably are not present in the Carboniferous. Therefore, the petroleum probably migrated from younger strata, most likely of Miocene age.