In the scarp due north of Harra, the Cenomanian sandstones and clays with _Exogyra mermeti_ and _E. africana_ are conformably overlain by a hard yellow crystalline limestone containing small nummulites; so that here the Eocene clearly overlies the Cenomanian beds. If this upper limestone bed be followed southwards along the scarp (see the sections on Plate VIII) it appears to be continuous as far as the road leading to Ain Haswi, where the ground forming the bottom of the oasis-depression rises to the level of the limestone, and the clays are completely hidden by sand and limestone-debris. There commences here, however, a considerable thickening of the limestones, and hard brown limestones, with calcite-filled cavities, and some soft earthy beds come in; so that here we have the beginning of the series (No 6) which has been described as recurring on the opposite scarp in the same latitude, and which forms the hills north-west of Harra. The topmost bed of the scarp is a hard crystalline limestone, which appears continuous with that containing nummulites further north, and the top of the plateau is therefore probably here also Eocene. A little further south, the plateau-surface is covered with countless small hills of white chalky limestones with siliceous beds; these beds were searched without result for fossils, but as they overlie the hard crystalline rock, above mentioned as probably Eocene, they must be of Tertiary age, and therefore do not correspond with the Danian white chalk of the western plateau. As the large hill near the plateau east-north-east of Ain el Haiss is approached, the thickening of the lower crystalline brown and grayish-white limestones is very marked, and here they probably comprise both Cenomanian and Danian rocks; but the dip south-eastward is so strong that the Eocene must be close to the edge of the plateau, while the folding doubtless accounts for the crystalline nature of the rocks and their poverty in fossils. South of the large hill, a second plateau is met with at a distance of about a kilometre eastward from the main scarp; this second plateau consists of soft chalky beds similar to those above-mentioned, underlain by clays and sandstones, while the main scarp still exhibits brown and grayish crystalline limestones, though both the dip and the thickness of these beds become gradually smaller. As the south point of the oasis is approached the limestones thin out, till at the end only a few beds of hard yellow-brown limestone occur in the clays; these beds are continuous with those containing Cenomanian fossils on the west plateau. Thus at the south-east portion of the scarp the Danian is either absent, or represented by very thin beds at a little distance from the oasis. It might be suggested that the soft chalky limestones which form the second or upper plateau correspond with the Danian white chalk of the west side; but several considerations tend to negative this view.