In the first place, it has been mentioned above that similar soft chalky limestones occur at about the same horizon further north, where they overlie beds which are probably Eocene. Again, on the line followed from the south end of the oasis of Minia, nummulites were found in abundance only a few kilometres away from the oasis. And lastly, these chalky limestones never show folding comparable with that of the lower beds, a fact which seems nearly conclusive in view of the unconformity known to exist at other points between the Cretaceous and the Eocene. If the Eocene age assigned above to the chalky limestones of the eastern plateau be correct, it is possible that the clays and sandstones which underlie and separate them from the Cretaceous limestones may represent the Esna Shales of the more southern oases, though sandstones are elsewhere absent from this series. _Unconformity and overlap._—From the above description of the Eocene rocks of Baharia we see that their relation to the underlying Cretaceous system is one of unconformable overlap.[53] In the north part of the oasis we have the Eocene (Up. Lib.-Low. Mok.) overlying directly the lower beds of the Cenomanian; further south, on the west, the same beds overlie the White Chalk of Danian age, and no doubt at an intermediate point the Eocene overlies the intermediate beds. On the east side, though the actual demarcation of the Eocene and Cretaceous beds is a matter of some difficulty, the difference of dip between the two systems in some localities is well marked. It seems certain then that after the deposition of the Cretaceous beds in this region, elevation took place with a considerable amount of folding (which will be noticed fully further on). The land thus formed underwent a marked denudation before subsidence took it below the surface of the sea and allowed of the deposition of the Eocene deposits just described. POST-EOCENE (OLIGOCENE?). 3. _Ferruginous grits and quartzites, with limonite and pisolitic iron-ore._ As already mentioned, one of the most striking topographical features of the oasis is the number of isolated black, and for the most part perfectly conical, hills within the depression. These hills are composed of the lower Cenomanian sandstones and clays of the Cretaceous, and owe their existence and dark colour to protecting caps of very hard, dark, ferruginous, silicified grits and quartzites, often associated with limonite. The first impression obtained on examining these rocks, is that they are merely silicified and ferruginous bands of the sandstone series below, which forms the general oasis-floor and part of the walls and hills.