Top.
1.Gravels of rounded flints and pebbles, thin covering.
2.White chalk, 2 metres.
3.Earthy limestone, 60 centimetres.
4.Red and white clays and marls, about 30 metres.
5.Sandy limestone, 20 centimetres.
6.Clayey limestone, 15 centimetres.
7.Sandy limestone, 60 centimetres.
8.Limestone conglomerate, 1 metre.
9.Red and yellow clays at base.

These beds appear to dip slightly eastward. No fossils were seen.

The top of the plateau is a huge level gravel-plain, with white chalky limestone showing through occasionally. Sometimes this rock shows a loose tufaceous texture; at other places it is sandy and fissile, and now and again it encloses small pebbles. A broad camel-road going south-east was crossed at 145 kilometres, and another in the same direction was crossed at 157 kilometres. At 162 kilometres, the gravelly ground having gradually fallen to 179 metres above sea-level, a turn so as to take again an eastward course was made, and a long stretch of gently undulating gravelly ground, with white limestone showing through in small patches, was traversed. A camel-road going east was crossed obliquely at 185 kilometres. At 196 kilometres, low gravel-covered hills of some extent were passed. The pebbles range up to 10 or 15 centimetres in diameter, and are well-rounded. In the lower part of one of these hills, sandy chalky limestone is seen cropping out through the gravel which covers the slope. Then a little further on are other low hills of white and grey nummulitic limestone, only thinly sprinkled with pebbles and sand. Some of the beds here contain cylindrical nearly vertical holes, one being measured and found to be 8 centimetres diameter and 45 centimetres deep.

Beyond the hills just mentioned is a further stretch of gravel, till at 199 kilometres a broad low ridge of white and creamy limestone, crowded with large nummulites (N. gizehensis) is reached. The beds of this ridge dip slightly west. The hollows of the ridge are full of blown sand. Beyond is a flat depression, the floor of which is strewn with small nummulites (N. curvispira), and with Ostrea and other shells; then another small nummulitic ridge is crossed, after which comes some hard smoky-grey silicified limestone, with much sand on the surface. At 202 kilometres from the starting-point a slight descent was made from the limestone on to a shelving gravelly tract with some sand-dunes. Some 4 kilometres further on the wide belt of low sand-dunes fringing the cultivated area west of Minia was entered. This sandy tract has a width of about 4 kilometres; it contains some patches of grassy land with pools of water.

The village of Nasl Nadiub Lengat, at the edge of the valley-cultivation, was reached after covering 212 kilometres from the south point of the oasis, the march having occupied about 60 hours.

To summarise the geology of the area crossed in the traverse just described, it will be clear that although the beds which form the top of the scarp at the south end of the oasis are probably of Upper Cretaceous age, yet these beds are overlain by Eocene limestone with nummulites at a short distance (about 10 kilometres) east of the Baharia-Farafra road. It is probable that the entire stretch of limestone-plateau between this point and Minia is Eocene, nummulites being recorded both from near the centre of the tract and from the edge of the desert near Minia. The softer chalky beds traversed appear stratigraphically lower than the Nummulite-limestone, and would seem to correspond to the chalky-limestones with Operculina libyca and Lucina thebaica which occur so constantly near the base of the Eocene in Kharga Oasis. The gravels, as already remarked in referring to the Minia-Baharia road, are of uncertain age, but are certainly Post-Eocene. The sand-dune belt crossed near the centre of the tract is the same as that crossed on the outward journey from Minia, and extends for a great distance north and south.

Baharia-Farafra road.The road from Baharia to Farafra, traversed by Cailliaud in 1820,[26] and by Jordan in 1874[27], was taken by a party of the Geological Survey in proceeding to Farafra after surveying the west side of Baharia. The start was made from the same point as the return traverse to Minia, viz., the point of ascent of the Farafra road at the south scarp of Baharia (lat. 27° 48′ 13″ N., long. 28° 32′ 49″ E. of Greenwich), and the general course taken was in a direction 30°-40° west of south. A second, almost disused, road from Baharia to Farafra ascends the western escarpment from the depression 3½ kilometres further north, follows a narrow plateau at the base of the chalk escarpment and joins the main road some distance south of the extreme end of the oasis-depression.

The main road after ascending the scarp at the extreme south end of the depression, at the point mentioned, proceeds at first in a direction about 30° west of south, over a limestone plateau, with sandstones and clays below. After 4 kilometres hard concretionary grey sandstones are noticed, and 3 kilometres further on a small hill of hard false-bedded grey sandstone is passed. The escarpment of the White Chalk now approaches within 2 kilometres of the road on the right hand, on the left being slightly further away. These escarpments run parallel with the road for some 5 kilometres, forming a large bay, until at 12½ kilometres the road passes through a narrow pass with the cliffs of white chalk quite close on either side. Almost immediately the cliffs again recede, forming a small bay opening into another still larger at 14½ kilometres. At this point an isolated chalk stack, with great masses of fibrous calcite at the base, is passed, and this hill makes a convenient point for a survey-station. Several more isolated hills are now passed and then the chalk scarps on either side close up and join, the road passing up the escarpment at the end of the bay and gaining the summit of the white chalk at 20½ kilometres. The beds forming the plateau between the end of the oasis-depression and this escarpment of white chalk belong to the middle series of the Upper Cretaceous, the “variegated clays and sandstones,” fully described in [Chapter V].

From the top of the white chalk escarpment the road continues in a well-maintained direction of about 40° west of south, over a more or less level gravelly plain with outcrops of hard crystalline limestone or chalk. Another, less used, road to Farafra, via the bay to the north-east of Ain el Wadi (in Farafra Oasis), probably branches off about this point. At 35 kilometres a small hill of siliceous limestone is passed and the chalk forms a slight escarpment a little way to the left.

About a kilometre further on a ridge of dark brown ferruginous sandstone is crossed and almost immediately afterwards, at 49 kilometres, the road descends through snow-white chalk cliffs into the depression of Farafra. The chalk forming the cliffs weathers in places to a smoky-black colour. At the bottom of the descent, which is gentle and presents no difficulties, an isolated hill occurs on the left and from this the dark clump of palms of Ain el Wadi is plainly visible bearing 9° west of south and distant about 16 kilometres. From Ain el Wadi to Farafra village is another day’s march of 43 kilometres, the road bearing about 35 west of south, but for details the reader is referred to the report on Farafra Oasis.[28] With regard to the geology of the road across the plateau separating Baharia and Farafra, the age of the beds first passed over has already been mentioned. After rising on to the white chalk the surface of this formation is followed right up to the descent into Farafra. Although occasional crystalline limestones are crossed, these, with the surface accumulations of flinty material, are only skin deep and the former probably represents the upper part of the chalk itself. No Eocene beds were observed, and it is extremely doubtful if any exist; in the latter case they would be patches of Operculina-nummulitic limestone from the base of the Esna Shales, as this limestone is sometimes left capping the surface of the white chalk after complete denudation of the shales above, as in the bay to the north-east of Ain el Wadi. We thus see that the Cretaceous of Baharia is continuous with that of Farafra and that the intervening desert is not formed of the Nummulitic limestones of the Eocene as formerly supposed and shown on the Rohlfs Expedition map.[29]