_A._—=Wadi Rayan Series.=—(_Nummulites Gizehensis Beds_).
(A.I.e. Schweinfurth, I.b. Mayer-Eymar,[36] Lower Mokattam of Cairo).
Beds of this group are chiefly found in the south of the
depression. The wadis Rayan and Muêla, as already shown by
Schweinfurth and Mayer-Eymar[37], are cut out in clays and limestones
of Lower Mokattam age; the upper beds of limestone, containing
among other fossil[38] numerous examples of the large _Nummulites
gizehensis_, form the greater part of the floor of the depression
west of the Fayûm cultivation, stretching from Jebel Rayan to the
foot of Gar el Gehannem,[39] 28 kilometres west of the western end
of the Birket el Qurûn (Section XX). Near the latter hill examples
of _N. gizehensis_ of inordinately large size occur.[40]
At the conical hill at the southern entrance to Wadi Muêla the
following beds were noticed:—
_Top of hill._
1. Hard white limestone with small nummulites, _Lucina_,
_Callianassa_, and echinids. Salt occurs in thin deposits along
joint-planes. The lower part of this bed is largely composed of
small nummulites and bryozoa. This generally white limestone
passes down into
2. Brown, usually sandy, limestone with oysters and small nummulites.
In it are intercalated thin beds of greenish brown sandstone and
clayey sand with impressions of bryozoa. Some of the brown sandy
limestones are full of small nummulites. _Ostrea_ and _Carolia_
numerous. The beds are not constant, the clayey sandstones passing
insensibly into sandy limestones.
3. Softer beds with large nummulites, corals, _Ostrea_, _Nautilus_.
4. Soft green and brown clays, with occasional oyster-beds.
At the corner of the cliff 7½ kilometres N.N.W. of the monastery of
Der el Galamûn, in Wadi Muêla, occur about 80 metres of hard white
nummulitic limestones, with beds of argillaceous sandstone and sandy
clays. Fossils are numerous and include nummulites of several species
(_N. gizehensis_, etc.), _Carolia placunoides_, different species
of _Ostrea_, with gastropods (among others _Terebellum sopitum_),
bryozoa, etc. It is very noticeable that the nummulites, especially
the small species, occur in remarkable profusion not only in the
limestones but often in the clays.
The following section will give a good idea of the general alternations
found in this area; it was measured at Jebel Rayan,[41] 24 kilometres
west of the western end of the cultivation of Gharaq basin.
_Top of plateau._ Metres.
1. Hard snow-white limestone with occasional nummulites
passing down into hard highly nummulitic limestone;
_N. gizehensis_, _Ostrea_ sp., _Lucina_ sp., _Mitra_ sp.,
and _Carolia placunoides_ occur among others 31
2. Vertical-faced bed of greenish clayey sands and sandy
clays (glauconitic) with _Carolia_, _Ostrea_ and
_Nummulites_. Near top of bed there is much gypsum. The
nummulites in this bed are often collected together so as
to form hard concretionary masses; these masses, by
becoming more numerous, finally form a hard bed of
nummulitic limestone intercalated in the clays near the
top. The junction of the clays with the limestone of Bed
No. 1 is very irregular 16
3. Greenish shelly sands and sandy clayey bands, interbedded
with impure chalky nummulitic limestones with _N.
gizehensis_, _N. curvispira_, and a third smaller species;
_Ostrea_ sp. This bed is much obscured by debris 11
4. Hard slate-blue shales, weathering to paper-shales 2
5. Brownish marls passing up into clays 2
Limestone band largely made up of small and large
nummulites and echinids 1
Glauconitic (?) and clayey sands and sandy clays,
with _Ostrea_, _Carolia_, and nummulites, weathering
with a vertical face. In some bands large numbers of
small and large nummulites lie embedded in every
position, as if tossed about by currents during the
process of becoming buried by sediment. Gypsum occurs
in thin veins and often encloses the nummulites 36
6. Hard markedly-white nummulitic limestone full of _N.
gizehensis_ and other species (_N. curvispira_, etc.);
the rock usually has a dark brown colour when freshly
fractured. A shelly band rich in corals occurs nine
metres from the top. The upper part is more marly and
less nummulitic than the rest of the bed. Base invisible 30
---
Total thickness of beds in the above section 129
---
[Illustration: PLATE V.
ALLUVIAL DEPOSITS OVERLYING MARLY LIMESTONES (RAVINE BEDS) IN EL WADI,
RAVINE NEAR QASR GEBALI.]
The following is a section of the beds exposed in Wadi Muêla compiled
from a paper by Mayer-Eymar on this oasis:—
_Top._ Metres.
{ { White siliceous cavernous limestone with
{ { _Lucina globulosa_, Desh., _Gisortia_,
{ { _Rostellaria_, _Eschara Duvali_,
{ { Michelin., (Probably ≡ bed No. 1 of our
{ { J. Rayan section) 10
{ {
{ { Greyish-yellow marl, rich in places with
{ Id. { _Ostrea Gumbeli_, _Pecten mœlehensis_,
{ { May.-Eym., _Vulsella chamiformis_,
{ { May.-Eym., _Velates Schmiedeli_, Chemnitz,
{ { _Cerithium fodicatum_, _Pleurotoma_,
{ { _Borsonia_, _Fusus_, _Rostellaria_, etc. 6
{ {
{ { Yellowish sandy marl, with small
{ { nummulites.
PARISIAN. {
{ { Yellowish marls, divided by one or two
{ { bands of red clay, with _Nummulites
{ { gizehensis_ 7
{ {
{ Ic. { Hard bedded clay 1
{ {
{ { Vari-coloured gypseous marls 4
{ {
{ { (Probably ≡ beds 2, 3, 4 at J. Rayan).
{
{ { Very hard, rich greenish-grey, siliceous
{ { limestone with _N. gizehensis_, _Pecten
{ { corneus_, J. Sow., and _Lucina_ (_L.
{ Ib. { consobrina_, Desh., and _L. Defrancei_,
{ { Desh.). 4 to 5
{ {
{ { (Probably ≡ upper part of bed 5 at J.
{ { Rayan.)
There is a considerable difference in thicknesses between the above
section and that of Jebel Rayan. Our heights agree closely with those
of Schweinfurth, so that it is probable that Mayer-Eymar is in error,
notwithstanding his challenge of Schweinfurth’s figures in the
paper mentioned.
_B._—=Ravine Beds.=
The beds of this series, consisting of gypseous clays, clayey marls,
and white marly limestones, are met with bordering the cultivation
on the east, west and north sides; they pass under the alluvial
soil of the cultivated land and are frequently seen in the bottoms
of canals, and especially in the deep ravines known as El Bats,
and El Wadi (Plates III and V). The relation of these beds to the
Rayan series below is well seen at the prominent outstanding hill
Gar el Gehannem (Fig. 2); here the plain to the east and south is
formed of the uppermost member of the Wadi Rayan series, a limestone
full of _Nummulites gizehensis_. In the hill itself the latter is
directly overlain by gypseous and glauconitic sandy clays and marls,
with hard intervening beds of yellowish, often marly, limestone. The
upper beds consist of alternating clays, sandy limestone and sandstone,
at the top being a thick bed of the latter passing up gradually into
the sandstones of the Birket el Qurûn series. The following is the
detailed section:—
_Summit of Gar el Gehannem._ Thickness in metres.
1. Hard yellow and white limestone crowded with }
shells, chiefly large individuals of _Carolia }
placunoides_ and _Ostrea Fraasi_. Numerous }
nummulites in upper part } 25
}
2. Limestone full of _Turritella carinifera_, }
_Ostrea Clot-Beyi_ } 1
}
3. Brown clays } Lower 6
} beds of
4. Shelly limestone with _Carolia_, _Turritella_, } Qasr el
_Ostrea_, _Cardita_ and _Qerunia_ } Sagha
(_Hydractinia_) } Series 1
} (45
5. Greenish clays } metres) 6
}
6. Nummulitic limestone with _Carolia_, _Qerunia_ }
and four species of _Turritella_ } 1½
}
Light blue clays } 2
}
7. Light green and brown sandstone with irregular }
concretions } 2½
8. Brown shelly limestone full of _Carolia }
placunoides_, _Ostrea Reili_, _O. Fraasi_, }
_Turritella_, _Balanus_ and nummulites } 2
}
9. Yellow sandstone with bands of shelly }
limestone crowded with nummulites, oysters, } Birket
etc. Near top casts of _Cardita_, _Carolia_; } el Qurûn
also _Cerithium_, _Teredo_, _Ostrea_, } Series
_Pecten_, _Pinna_, and echinids. Calcareous } (50
concretions near base } metres) 18
}
10. Clays with much gypsum } 6
}
11. Yellow sandstone with _Balanus_. Bands }
crowded with two species of nummulites and }
occasional oysters. In places the }
foraminiferal bands become highly }
calcareous. Below similar, with hard }
compact grey bands and occasional fish-spines }
and teeth } 24
12. Similar to above, with numerous casts of }
_Cardita_, etc., and small _Ostrea_ } 24
}
Argillaceous sandstone with thick stockwork }
of gypsum and calcareous nodules } 6
}
13. Light yellow, brown, and greyish gypseous clays } 3
}
14. Yellow-brown sandstones and sandy limestones, }
often argillaceous. Fish-scales. }
}
Brown clays }
}
Yellow-white marls and marly limestone } Ravine 5
} Beds
15. Hard light yellow shelly limestone, in part } (10
marly, in part sandy } metres) 10
}
16. Ochreous-yellow, grey, and white clays and }
marls with gypsum } 9
}
17. Hard yellow-white shaly marl with numerous }
shell-impressions; much gypsum } 3
}
18. Yellow marly clays; soft yellow and grey-brown }
clays, dark sandy glauconitic, yellow, and }
black, clays. _Zeuglodon_ remains fairly }
common. Shell impressions. Much gypsum }
}
Fairly hard yellow-white glauconitic marl } 10
Marly limestone with _Nummulites gizehensis_ forming top of
Rayan beds.
[Illustration: FIG. 2.—Section at Gar el Gehannem, showing the
relation of the Wadi Rayan Series to the Ravine Beds.]
The clays, marls, and limestones of the Ravine beds are generally found
to contain fairly numerous shell-impressions, including _Nucularia_
sp., _Leda_ sp., _Cardita_ sp., _Corbula_ aff. _pixidicula_, _Lucina_
sp., _Oudardia ovalis_, Desh., _Tellina tenuistriata_,[42] numerous
small fish-scales, and occasional large teeth of sharks; while the
skeletons of the toothed-whale _Zeuglodon Isis_ are fairly common,
although usually in poor preservation.
In the ravine of El Bats, about one kilometre west of Sêla, these beds
(5-6 metres thick) are seen unconformably overlaid by 12 metres of
false-bedded gypseous sands and clays passing up into the superficial
cultivated loam. The junction of these alluvial deposits and the
underlying Eocene is distinctly unconformable and an intervening
pebble-bed is occasionally present (Fig 3).
In the large ravine known as El Wadi, which traverses the west side
of the cultivation of the Fayûm, these beds are frequently well
exposed; their lithological characters remain very constant. Here,
as in El Bats, they are unconformably overlain by a varying thickness
of Pleistocene and Recent clays. Their surface, a plain of subaerial
denudation, represents the original floor of the depression before
the entry of the sediment-carrying water from the Nile Valley through
the Lahûn gap; its irregularity is seen in Plate V.
The plain bordering the cultivation to the east of Sêla and Rubiat
likewise consists of these same white marls with fish-scales,
etc.; they pass regularly under the cultivated land. Shaly marls,
gypseous clays, and chalky limestones of the same age are seen in,
and to the south of, the railway crossing the desert between Sêla
and Medum. Eastwards they stretch into the Nile Valley, being found
exposed along the desert-edge bordering the cultivation at Medum,
Nawamis and Masaret-Abusia.
{ 1. Marsh and poorly cultivated land.
{
RECENT { 1a Cultivated loam.
AND {
PLEISTOCENE { 2. Sands and clays, with gravelly bands;
{ often concretionary and gypseous beds.
{
{ 3. Pebble-bed marking unconformable junction.
MIDDLE } RAVINE { 4. Gypseous saliferous marly clays, white
EOCENE } BEDS { marls and limestone with fishscales and
} { _Tellina Corbula_, etc.
FIG. 3.—Sketch-Section across _El Bats_, 1 kilometre West of Sêla.]
The same beds are exposed immediately to the east of the village of
Sersena, midway between Sêla and Tamia. They are again well seen
in the ravine below the last named village, and forming the narrow
strip of the desert projecting into the cultivation as far as the
northern end of the Tamia lake; they also occur on the shore of the
latter at El Tuba, about 2 kilometres south of the village. At Tamia
their exposure measures 25 metres in thickness.
At various points along the north side of the Birket el Qurûn
exposures of this series occur, the beds forming the lower sloping
part of the cliffs overlooking the lake, as well as the base of the
island “Geziret el Qorn,” although only the upper beds are visible
above the water of the lake. Both here and along the northern shore of
the lake they are for the most part hidden by the high level recent
lacustrine clays, but where occasionally exposed their identity is
certain, the characteristic small brown fish-scales being abundant,
besides occasional teeth, with shell-impressions of the different
genera enumerated above.
[Illustration: PLATE VI.
ESCARPMENT OF THE BIRKET EL QURUN SERIES NEAR THE WESTERN END OF
THE LAKE.]
At the western end of the lake the Ravine beds form the lower part
of the cliff as well as the plain to the south; the underlying
_Nummulites gizehensis_ limestone not being exposed. The series
consists of some 45 metres of white and grey shaly marls with harder
bands of siliceous limestone intercalated throughout, one of which
usually forms the uppermost bed. It is, in fact, the development in
places of one or other of these hard beds of limestone near the top
of the series that gives rise to the bold promontories, or horns,
which occur on the north side of the Birket el Qurûn.
The greater part of the marls and clays met with from 18·5 to 112·5
metres below the surface in the boring at Medinet el Fayûm in all
probability belong to the Ravine beds.
The maximum thickness of this series is 70 metres, measured at Gar
el Gehannem.
_C._—=Birket el Qurun Series= (_Operculina-Nummulite Beds_).
The above designation is convenient and applicable to these beds,
which form the escarpment immediately overlooking the lake on the
north side throughout its length.
The group includes all the beds between those last described and
the well-marked Qasr el Sagha series, homotaxial with the Upper
Mokattam (the brown beds) of Jebel Mokattam, near Cairo. It thus
appears to be the equivalent of the upper part of the white
beds (quarried limestones) of the Mokattam section, although
the lithological characters are entirely different, the massive
limestones of Jebel Mokattam being represented in the Fayûm by an
arenaceous and argillaceous series, deposited probably in water of
far less depth. Where the different members of this series are well
exposed certain beds are found to be characterized by the abundance
of two foraminifera, the one a small thin-shelled _Operculina_
(_O. discoidea_)., and the other a small thick nummulite.[43] The
tests of these foraminifera sometimes make up entire bands of rock. In
addition, the series includes certain beds which at times become very
fossiliferous, and contain a well-preserved molluscan fauna.
The series is well seen in the desert separating the Fayûm from the
Nile Valley; on the south-east and east sides of the former; along
the northern boundary of the cultivation and the Birket el Qurûn;
and westwards in the cliffs to beyond the outlying hill-mass of Gar
el Gehannem.
The following section was measured on the south-west of the Fayûm,
from Ezba Qalamsha (on the confine of the cultivation) to the ridge
summit 5 kilometres to the south-east.
_Top._ Metres.
Summit of ridge 5 kilometres south-east of Ezba
Qalamsha.
Pliocene Raised Beach with occasional _Ostrea
cucullata_, Born., made up of gravels with
blocks of limestone.
{ 1. Ochre-coloured calcareous sandstone and sandy
{ limestone crowded with foraminifera
{ (_Nummulites Fraasi_, etc.), _Ostrea_, etc. 38
{
{ 2. Sandy limestone, largely made up of
{ foraminifera (_Operculina discoidea ?_) 2
{
{ 3. Sandy shale 2
{
{ 4. Sandstone, partly calcareous, with much
{ gypsum 3
{
{ 5. Calcareous sandstone with concretionary
BIRKET { weathering 17
EL QURUN {
SERIES. { 6. Shale with gypsum 2
{
{ 7. Calcareous sandstone 4
{
{ 8. Shale with gypsum 2
{
{ 9. Calcareous sandstone, hard and yellowish 2
{
{ 10. Gypseous shale with numerous small shells
{ (_Tellina_ sp.) passing down into sandy
{ limestone. (This bed is the uppermost member
{ of the Ravine beds) 6
--
Total thickness 78
--
_Base, cultivation level._
To the north of the Lahûn pyramid the beds agree generally with the
above. The following are the chief divisions here:—
_Top of Hills._ Metres.
Gravel Terrace (Pliocene) 22 metres thick.
1. Calcareous sandstone and sandy limestones full of
nummulites; also _Ostrea_, etc. 31
2. Ochre-coloured calcareous sandstone or sandy limestone,
often crowded with _Operculina discoidea_ and some
_Nummulites Fraasi_, etc. 12
3. Sandy limestone with small foraminifera at top and
some shells. The upper part of this bed has been
quarried 20
4. Shales and shaly limestone; gypsum —
--
Total thickness 63
--
The foraminiferal sandy limestones of this series are seen at points
in the desert bounding the eastern margin of the cultivation, notably
east of Sersena and at the top of the hill 15 kilometres north-east
of Rubiat.
The following section was measured at the prominent hills 17 kilometres
28° N. of E. (magn.) of Tamia:—
Metres.
1. Greyish laminated sandy clays with gypsum; _Ostrea_
band near top 7
2. White sandy limestone with numerous badly preserved
_Ostrea_, _Pecten_, and other lamellibranchs 1
3. Dark-brown clayey sands with gypsum and grey sandy
clays with obscure plant-remains. Occasional _Ostrea_ 14
4. Hard, white, sandy limestone with numerous _Ostrea_
at top; soft clays with gypsum 1
5. Greenish and brownish sands and sandy clays with }
band of sandy limestone near top }
} 14
6. Greyish-brown, impure, sandy limestone weathering }
into large globular concretions. Shell impressions }
7. Sandy clays and marls alternating with impure }
limestones; much gypsum. Occasional fish-remains and }
small oysters } 22
}
8. Greenish sandy limestone with traces of shells }
9. Finely laminated grey-brown clays with black
carbonaceous matter and fish-remains; saliferous 3
10. White sandy limestone 1
11. Soft yellow sandstones, etc. }
}
12. White marls with fish-scales, etc.; base not seen. } 7
(This bed, and possibly also 9, 10, 11, should be }
reckoned as belonging to the Ravine beds) }
--
Total thickness 70
--
In the north of the Fayûm the series is characterized by the
presence of one or more very constant well-marked beds of hard
calcareous sandstone, which almost invariably weather into huge
globular masses. These masses should be regarded as huge weathered-out
concretions, rather than as water-rounded blocks, although no doubt
in many cases their roundness has been increased by the action of the
waters of Lake Moeris as the level of the latter gradually fell, and
possibly still earlier during the invasion of the Pliocene sea; from
the latter time also may date the millions of parallel vertical borings
with which these and other exposed rocks are often perforated. In
the various places where one of these beds forms the present surface
of the desert the concretions may be seen in different stages of
exposure, from the initial, where only just the tops are laid bare,
to the final stage where the globes are left completely weathered out,
as seen in the illustration (Plate VII). The appearance of the desert
when covered for many square kilometres with thousands of these blocks
is more easily imagined than described.
The lower beds of the Birket el Qurûn series form the island Geziret
el Qorn, and consist of clays and sandstones containing a considerable
number of organic remains. These beds were collected from and examined
by Schweinfurth[44] in 1879, the mollusca being subsequently described
by Mayer-Eymar,[45] while the vertebrate remains, which included
cetacean bones and numerous fish-teeth, were submitted to Dames.
The following species were determined by Mayer-Eymar, who indicated
that the fauna as a whole had a Bartonian aspect[46]:—
UPPER BED.
_Ostrea plicata_, Defr.
_Arca Edwardsi_, Desh.
_Lucina pomum_, Duj.[47]
_Lucina_ cfr. _tabulata_, Desh.
_Cardium Schweinfurthi_, May.-Eym.
_Cytherea Newboldi_, May.-Eym.
_Tellina pellucida_, Desh.
_Mactra compressa_, Desh.
_Corbula pyxidicula_, Desh.
_Calyptræa trochiformis_, Lam.
_Turritella angulata_, Sow.
_Ficula tricarinata_, Lam.
LOWER BED.
_Astrohelia similis_, May.-Eym.
_Goniastræa cocchii_, d’Achiardi.
_Heliastræa acervularia_, May.-Eym.
_Heliastræa Ellisi_, Defr. (_Astræa_).
_Heliastræa flattersi_, May.-Eym.
_Ostrea digitalina_, Dubois.
_Ostrea gigantea_, Sol.
_Ostrea longirostris_, Lam.
_Ostrea producta_, Delb. et Raul.
_Isocardia cyprinoides_, Braun.
_Turritella carinifera_, Desh.
_Turritella transitoria_, May.-Eym.
_Turritella turris_, Bast.
_Turbo Parkinsoni_, Defr.
_Pleurotoma_, sp.
The cetacean remains, belonging to the genus _Zeuglodon_, were
described by W. Dames,[48] who compared them with the American species
_Z. macrospondylus_ and _Z. brachyspondylus_, but did not then consider
them to represent a new species; in a later publication,[49] however,
the same author described similar but more complete remains, also
collected by Schweinfurth (from beds belonging to our Qasr el Sagha
series), as a new species, _Z. Osiris_. A considerable number of
fish-remains from Geziret el Qorn are also described in the earlier
publication. Although the difference in size of the bones of separate
individuals was considered by Dames to be sexual, it seems probable
that there are two distinct species of _Zeuglodon_, as the smaller
type appears to have a much greater upward range than the larger[50];
both species, _Z. Osiris_, and _Z. Isis_ occur in the Birket el Qurûn
series, and a very fine mandible of the larger was obtained from these
beds in the cliffs near the west end of the lake.[51] More recently
a third species has been discovered by Stromer and described under
the name of _Z. Zitteli_.[52]
[Illustration: FIG. 4.—Profile of beds of Geziret el Qorn.
1. Hard brown sand-rock with large concretions of weathered globular
sandstone on the summit; ferruginous nodular bands containing
shell-casts occur near top. 2. Soft gypseous clays with bands of
sand-rock and sandstone with _Ostrea_, _Cardium Schweinfurthi_,
_Turritella_, corals, _Zeuglodon_, chelonian and fish-remains. 3. Brown
sand-rock. 4. Soft gypseous clays and harder brown sandstones. 5. White
shaly marl with fish-scales; hard band at top and soft sandy shaly
clays below.
The surface-slope is much less than shown in sketch and is generally
covered by a deposit of lacustrine clays containing freshwater shells
and fish-bones.]
The accompanying profile (Fig. 4), measured during a hurried visit
to the island for the purpose of correlating these beds with those
of the mainland, shows the character of the lower beds of the Birket
el Qurûn series at this point.[53]
[Illustration: PLATE VII.
WEATHERED CONCRETIONARY SANDSTONE (BIRKET EL QURUN SERIES) ON NORTH
SHORE OF LAKE NEAR GEZIRET EL QORN.]
The upper beds of the Birket el Qurûn series in this part of the
Fayûm are lithologically similar to those just described, consisting
of alternating clays and sandstones, about 37 metres thick. They are,
however, generally much richer in fossil remains, which are likewise
usually better preserved than in the lower beds. Some of the brown
sandstones of this series are literally crowded with perfect examples
of many of the typical mollusca; and further west, near the end of
the lake, foraminiferal bands again become noticeable. Near Dimê the
escarpment of these and the lower beds is gentle and inconspicuous,
but followed westwards it becomes a bold precipitous cliff, increasing
in height towards the western end of the lake, where it is capped by
the lower beds of the Qasr el Sagha series.
The following section was measured on the mainland[54] opposite the
island Geziret el Qorn.
_Top._ Metres.
1. Gypseous clays, separated by a band of brown sandstone
crowded with white well-preserved shells, including
numerous individuals of _Plicatula polymorpha_, _Ostrea_,
_Turritella_ and _Lucina pharaonis_. Large vertebrae of
_Zeuglodon Isis_ occur on this horizon further to the
north-east 8
2. Sandstones and gypseous clays. Although here the
sandstones are not hard or predominant, this bed is
equivalent to the hard sandstone full of borings capping
the plain between the ruins of Dimê and the top of the
escarpment overlooking the lake. Further north this bed
often contains numerous _Carolia placunoides_ and _Ostrea_ 3
3. Gypseous clays 3
4. Clays, brown sandstones, and occasional beds of limestone,
often very fossiliferous, containing _Ostrea Reili_,
_Carolia placunoides_, _Cardita Viquesneli_, d’Arch.,
_Lucina_ sp., _Turritella pharaonica_,[55] _Clavelithes
longævus_, _Qerunia cornuta_, etc., etc. 10
5. Clays with fossils as in last bed, capped by hard band of
shelly sandstone 3
6. Alternating yellow-brown sandstones and gypseous clays 10
--
Total thickness 37
--
Bed with weathered-out sandstone concretions at top—upper bed of
section at Geziret el Qorn.[56]
At the western end of the Birket el Qurûn the series is well marked,
the sandstone beds forming the steep face of the bold precipitous
cliffs which are so marked a feature at this end of the lake. The group
has a thickness of some 50 metres and is overlain by the lower beds
of the Qasr el Sagha series; it is more convenient here to give the
entire section of the cliffs down to the base of the series under
discussion:—
_Top of Cliffs._ Metres.
1. Hard grey sandstone and shelly limestone }
passing up into calcareous sandstone }
(forming surface of plain dipping north). }
}
2. Impure sandstone with numerous fossils:— }
_Qerunia cornuta_, corals, _Ostrea Reili_, }
_O. Clot-Beyi_, _Carolia placunoides_, }
_Plicatula polymorpha_, _Cardita_ }
(? _fajumensis_) sp., _Clavelithes }
longævus_, _Serpula_, etc. }
}
3, 4. Clays with band of argillaceous } Lower part
sandstone. Septaria bed near base. }(42 metres)
Fish-remains. } of Qasr
} el Sagha
5. Earthy limestone crowded with _Ostrea } Series.
Clot-Beyi_, _O._ sp., _Plicatula }
polymorpha_, _Pecten_ sp., _Lucina_ sp., }
_Cytherea_ sp., _Turritella_ sp., }
_Nonionina_ sp., _Oliva_ sp., _Pleurotoma_ }
sp., _Vermetus_ sp., _Nautilus_ sp. }
}
6. Thin-bedded clays, grey with yellowish band, }
sandy clays interbedded with soft whitish }
sandstones with small irregular concretions. }
Clays, gypseous and sometimes carbonaceous. }
}
7. Shelly sandstone, hard on upper surface and }
very fossiliferous (forms similar to Bed 9). }
}
8. Gypseous clays. }
9. Thin (·25 to ·5 metre) hard dark
reddish-brown, very ferruginous,
concretionary-weathering sandstone with
nummulites and _Operculina_ and
well-preserved examples of _Qerunia
cornuta_, _Pecten_ sp., _Pectunculus_ sp.,
_Venus_ sp., _Cardita Viquesneli_, _Astarte_
sp., _Macrosolen Hollowaysi_, _Lucina_ sp.,
_Natica_ sp., _Cerithium_ sp., _Clavelithes
longævus_, _Voluta_ sp., _Dentalium_ sp. 1
10. Hard purplish clays 7
11. Soft yellowish sandstone with _Ostrea_
sp., _Cardita ægyptiaca_, _Lucina_ sp.,
_Turritella_ sp., and sharks’ teeth. Upper
surface tends to become dark, ferruginous,
and concretionary 1
12. Purple clays, with strings of gypsum 6
13. Soft light-yellow sandstones with harder
shelly bands and occasional concretionary
beds, forming vertical cliff-wall 17
14. Grey and brown clays 18
--
_Ravine Beds._ Total 50
--
In the cliffs west of the end of the lake the upper bed No. 9 continues
highly fossiliferous and yields the most perfectly preserved molluscan
remains to be found in the Fayûm and probably in Egypt.
A few kilometres east of the end of the lake a band of large globular
concretions occurs in the thick brown sandstone forming the vertical
face of the cliff. In many places the effect of weathering of these
rocks is of some interest, numerous “earth-pillars” having been
formed; these are largely the result of the action of blown sand,
assisted by rain, the concretions being left capping pillars of
brown sandstone, the sides of which are sculptured by the wearing
action of sand. The curious perforate or cellular appearance which
the weathered surfaces of this sandstone assume after long exposure
are particularly noticeable in this neighbourhood and in the Zeuglodon
Valley further west.
In the well-marked hill distant 17 kilometres to the north-east of
Gar el Gehannem, the soft fossiliferous sandstones of this series are
crowded with _Operculina_, _Nummulites_, and many species of mollusca
beautifully preserved.
At Gar el Gehannem the series is seen (Fig. 2 and detailed section
page 36) forming part of the slope of the hill, underlain by the
Ravine beds, and capped by part of the Qasr el Sagha series. It here
consists of yellow sandstones divided by a bed of clay; the sandstones
are often crowded with nummulites (of two species); also _Operculina_
(_discoidea?_), echinids, _Balanus_ sp., _Ostrea Reili_, _O. Fraasi_,
_Carolia placunoides_, and species of _Pecten_, _Pinna_, _Cardita_,
_Teredo_, _Turritella_, and _Cerithium_.
[Illustration: FIG. 5.—Section of cliffs, western end of the Birket
el Qurun.
Pleistocene.—(_a_) Lacustrine clays and sands with freshwater shells
and fish-remains; _Middle Eocene_, 1. 14 Clays, sandstones and impure
limestones; 15 White shaly clays and marly limestones.]
In the Zeuglodon Valley, 12 kilometres W.S.W. of Gar el Gehannem,
the brown sandstones of the Birket el Qurûn series are divided by a
narrow band of fine-bedded grey clay. Most of the fantastically shaped
hills on the south-west slope of the valley are carved out of the
lower division of the sandstone. The concretionary beds of the Birket
el-Qurûn series are not developed in this neighbourhood. Remains of
_Zeuglodon_ of both species (_Z. Osiris_ and _Z. Isis_) are remarkably
abundant and the skeletons of these cetaceans may be found in every
stage of weathering. The larger species, _Z. Isis_, is the more
common, and series of vertebrae, twelve to fifteen in number, can
frequently be counted in situ. The remains are most abundant enclosed
in the hard brown nodular bands of the series but in such cases it is
almost impossible to extract specimens of any value. In one instance
an almost complete skull of _Z. Isis_, measuring 116 cm. in length,
was found enclosed in a large block of the nodular rock.[57] Bones are
frequently to be observed protruding from the wind-worn sides of the
small hills, while those portions of the skeleton already weathered
out litter the ground below. Exposed they break up with rapidity,
although where the enclosing rock is softer than the bone itself,
parts of the skeleton beautifully preserved and perfectly free from
matrix may sometimes be obtained.
The molluscan fauna is represented by very large numbers of
pseudomorphs in sulphate of strontium (celestine) of the genera
_Lucina_, _Turritella_, _Fusus_ and _Nautilus_, the profusion of
individuals of a species of the latter being very marked. In the case
of lamellibranchs the radiating bundles of crystals of celestine are
seen to originate from a point placed centrally on one of the valves,
so that on this side (of a slightly weathered example) a radiating mass
of crystals is seen, while on the other appear numerous contiguous
circular areas, representing the terminal ends of the bundles of
crystalline fibres or needles. Apart from the quantities of organic
pseudomorphs, masses of crystalline celestine occur in the sandstones
throughout the valley, and altogether the quantity of sulphate of
strontium present must be very great. The gigantic oysters and other
fossils which occur in some of the overlying higher beds, and the
numerous individuals of nummulites in the sandstone itself, never
seem to be replaced by celestine.
Nummulites of two species are very abundant in some bands and the
presence in the Zeuglodon Valley of occasional individuals of the
large _N. gizehensis_ shows that in favourable localities this species
persisted throughout the time represented by the deposition of the
Ravine beds and ranged upward into the basal members of the Birket
el Qurûn series.
In the higher hills within the valley, and in the hill-mass on the
south side, the yellow sandstones of the Birket el Qurûn series
pass up into the basal members of the Qasr el Sagha series. In their
upper limits the sandstones become very nummulitic in places and at
the top bands made up of _Carolia_ and _Ostrea_ occur. Above these,
in the basal members of the Qasr el Sagha series, huge oysters and
finely preserved specimens of _Qerunia cornuta_ are conspicuous.
The dip in the valley is 2° north.
The southern face of the hill-mass lying immediately to the south of
the Zeuglodon Valley is an almost sheer cliff of over 100 metres,
descending to the silt covered basin below which has already been
noticed (page 23). On this escarpment the hard nodular marly limestones
of the Ravine beds are seen near the base, overlain by a mass of grey
shaly gypseous beds; above, forming as a rule a vertical wall of rock,
lies the hard massive brown sandstone of the Birket el Qurûn series,
here undivided by clays; at the top, highly fossiliferous alternating
clays and limestones are found forming the summit of the hills.
The exact junction between the Birket el Qurûn series and the
overlying Qasr el Sagha beds is naturally perfectly arbitrary, many
of the fossils being common to both groups. _Carolia placunoides_,
which is perhaps the most abundant fossil in the Qasr el Sagha series,
is sometimes very common in the upper beds of the underlying group,
and, as shown before, is common enough in the still lower _Nummulites
gizehensis_ beds of Wadi Rayan. So that, though this fossil itself is
no criterion, its relative abundance in the upper series justifies
those beds being called the “Carolia beds,” the additional name
of the Qasr el Sagha series being taken from the old ruin of that
name where these beds are fully seen.
[Illustration: PLATE VIII.
MIDDLE EOCENE ESCARPMENT (QASR EL SAGHA SERIES) 12 KILOM. WEST OF
QASR EL SAGHA.]
_D._—=Qasr el Sagha Series= (_Carolia Beds_).
This division is strikingly developed in the north of the Fayûm,
where it forms a bold escarpment of great length, consisting of
an alternating series of very fossiliferous clays and limestones,
with sands and sandstone in the upper beds, of a total thickness of
175 metres.
This series is the equivalent of the well known Upper Mokattam beds of
Jebel Mokattam, immediately to the east of Cairo. The cliffs of this
hill are among the best known in Egypt and have been studied by many
geologists, including Zittel, Schweinfurth, Mayer-Eymar, etc.; these
authors have classified the whole of the Upper Mokattam of Cairo as
equivalent to the Upper Parisian (Middle Eocene) of Western Europe. The
series is far better developed in the Fayûm than at Jebel Mokattam,
where the total thickness is only some 70 to 80 metres.
In consequence of the discovery in these beds of a highly interesting
vertebrate fauna, including land animals, the series becomes of
the greatest importance. As already mentioned, as long ago as 1879,
Schweinfurth, during a journey across the Fayûm, obtained remains of
_Zeuglodon_ in the underlying series from the island in the Birket
el Qurûn. Subsequently[58] he obtained additional remains of the
same cetacean in a violet marl belonging to the present series, from
a locality 12½ kilometres west of Qasr el Sagha[59]; these remains,
as already mentioned, were described by Dames as _Z. Osiris_. Since
then important finds of land and marine mammals and reptiles have been
made in different beds of this series; these will be referred to later.
The outcrop of the Qasr el Sagha series occupies a large part of
the northern desert of the Fayûm. The beds are, however, best seen
in the cliffs about 8 kilometres north of the Birket el Qurûn,
where they form a steep double escarpment, running east and west,
nearly parallel to the northern shore of the lake. The dip of the
series being northward at a very low angle, and the upward slope
of the ground being in the same direction, this cliff dies out a
few kilometres north-east of Qasr el Sagha. A little further north,
however, a N.W.-S.E. fold and fault again exposes nearly the whole
of the beds of the series, forming prominent cliffs as before.
In the conspicuous hill 17½ kilometres 28° N. of E. (magnetic) of
Tamia the series consists of innumerable alternations of clays and
sandy limestone. The calcareous beds nearly always contain numerous
examples of _Carolia placunoides_, _Ostrea_ and _Turritella_ of
several species, but other well-preserved fossils are rare. The
exposed beds here have a thickness of about 55 metres, and are
underlain by the Birket el Qurûn beds with a well-marked band of
concretionary sandstone, the thickness of the two series together
being 127 metres. The upper beds of the former series are not here
exposed, the top of the hill being formed of well-rounded flint
and quartz pebbles embedded in a base of finely crystalline gypsum
(2 metres thick), a deposit of Pleistocene times.
To the north of Tamia a large area of desert is occupied by the beds
of this series; the district has the character of an undulating plain
with occasional groups of hills and low irregular escarpments. At
the groups of hills 12 kilometres N.N.E. of Tamia, and just to the
east of Garat el Faras, the Qasr el Sagha beds are found to consist
as usual of an alternating series of sands, sandstones, clays, marls
and limestones, with numerous individuals of _Ostrea_, _Carolia_
and _Turritella_, besides vertebræ, teeth and spines of large fish.
We may pass now to the locality where this series shows its best
development and exposure, the beds being all concentrated in one
bold escarpment, generally divisible into an upper and a lower
cliff. These cliffs overlook the Birket el Qurûn, although distant
usually about 8 kilometres, being separated from the lower escarpment
of the Birket el Qurûn series (immediately above the lake shore)
by a broad plain, the surface of which is usually the dip-slope of a
hard bed of sandstone. From Qasr el Sagha (6½ kilometres N.N.E. of
Dimê) these cliffs trend westward, keeping approximately the same
distance from the north shore of the lake; they have been followed
and mapped for a distance of 70 kilometres to a point 13 kilometres
N.N.W. of Gar el Gehannem, whence they could be seen still trending
in a direction slightly south of west (see Plate XVII).
Small faults are of frequent occurrence along these escarpments, but
are not of other than local interest; they almost invariably have their
downthrow to the north, and it seldom exceeds a few metres. Fig. 5
shows a section through one of these faults near Qasr el Sagha.
The following detailed section (Plate XXIII) will show the character
of the beds forming this division. As might be expected in such a
series, although the calcareous bands are fairly constant, there is
a continuous change of character among the sandy and clayey sediments
from point to point; the false-bedding is in places very striking.
The main part of the section was measured 3½ kilometres north-east
of Qasr el Sagha, but the lower beds not being exposed at that point,
they were added from the cliffs at the ruin itself. The total thickness
is 154 metres.
Thickness
_Top._ in metres.
1. Hard, white, grey-weathering, sandy limestone with
numerous shell-casts: _Echinolampas Crameri_,
Loriol, _Plicatula Bellardi_, May.-Eym. 2
2. False-bedded sand and sand-rock with grey and
green clays; concretions and bands of ironstone.
Hard, dark-brown or purplish ferruginous sandstone
band. Occasional vertebrae of _Zeuglodon Osiris_,
Dames, _Pterosphenus_ (_Mœriophis_)
_Schweinfurthi_, Andr., crocodilian and fish-
remains; coprolites 16
3. Hard, calcareous, ferruginous, clayey sandstone
with brown ironstone concretions. Occasional fish-
spines.
Clays with massive veins of gypsum forming a
stock-work, and left weathered out above surface.
_Cardium Schweinfurthi_, May.-Eym., _Cardita
fajumensis_, Oppenh., (_Cossmannella ægyptiaca_,
May.-Eym[60]), _Crassatellithes_ sp. 9
4. Hard, yellow, gypseous sandy limestone or
calcareous sandstone 1½
5. Sandy, glauconitic clays with gypsum; oyster-bed
at base in places. _Alectryonia Clot-Beyi_,
Bellardi, _Exogyra Fraasi_, May.-Eym. 10
_2nd escarpment._
6. Hard or friable limestone, sometimes sandy, full
of _Carolia placunoides_, Cantr., and _Exogyra
Fraasi_, also _Ostrea_ aff. _heteroclyta_, Defr.,
_Ostrea Reili_, Fraas., _O. elegans_, Desh.,
_Plicatula Bellardi_, May.-Eym., _Pectunculus (?)
ægyptiacus_, Oppenh., _Qerunia_ (_Hydractinia_)
_cornuta_, May.-Eym. 2
7. Purplish clays interbedded and remarkably current-
bedded with ash-grey sands, with both ferruginous
and highly carbonaceous bands with plant-remains,
lignite and natural charcoal. Vertebrate remains
fairly common, the mammalian including _Zeuglodon
Osiris_, _Eosiren libyca_, Andr., _Mœritherium
Lyonsi_, _Barytherium?_ Andr.; the reptilian
_Stereogenys Cromeri_, Andr., and _Tomistoma
africanum_, Andr., with numerous coprolites; also
frequent remains of siluroid and other fish.
Masses of coral, _Astrohelia similis_, Felix, in
places 12
8. Hard grey, close-grained, concretionary sandstone,
frequently weathering into huge elongated rounded
masses; _Turritella pharaonica_, Cossm.
Hard, purplish clays with grey sandy clays,
sandrock, etc. Occasional crocodile and fish-
remains 4
9. Hard ripple-marked sandstone. False-bedded
sandstones with clay partings; ferruginous and
lignitic bands with lumps of lignite. Occasionally
coprolites and remains of Sirenia and Crocodilia
are numerous 7
10. Hard or friable brown sandy limestone with shell-
casts filled with scalenohedra of calcite.
_Carolia placunoides_, _Turritella_ sp. ½
11. Gypseous clays, with red ferruginous band;
weathering to paper-shales below 4½
12. Light-yellow limestone and calcareous sandstone
with sharks’ teeth, _Mesalia fasciata_, Lam.,
_Cassidaria_ sp., _Rimella rimosa_, Sol.,
_Trachelochetus bituberculatus_, Cossm.,
_Turritella carinifera_, Desh., _T. Lessepsi_,
May.-Eym., _Cardita fajumensis_, Oppenh.
_Goniopora?_ 1
13. Slate-blue and brown gypseous clays with band
containing _Mesalia_ sp., _Cassidaria nilotica_,
Bell., _Exogyra Fraasi_ and _Goniaræa elegans_ 3
14. Sandstone and sandrock, light yellow 1
15. Yellow sandy friable limestone with casts of
shells and _Mesalia fasciata_, _M. oxycrepis_,
May.-Eym., _Turritella Lessepsi_, _T. pharaonica_,
Cossm., _Alectryonia Clot-Beyi_, _Ostrea Reili_ ½
16-17. Sands, sandy clays and clays with a double band of
limestone containing _Ampullina hybrida_, Lam.,
_Melongena nilotica_, var. _bicarinata_,
May.-Eym., _Tudicla_ aff. _umbilicaris_,
May.-Eym., _Turritella Lessepsi_, _T. parisiana_,
May.-Eym., _Solarium_ sp., _Alectryonia Clot-
Beyi_, _Plicatula polymorpha_ (occasional),
_Lucina fortisiana_, Defr., _L. pharaonis_, Bell.,
_Mytilus affinis?_ J. and C. Sowerby, _Astrohelia
similis_, _Goniaræa elegans_, Mich.; numerous
vertebrate remains both above and between
limestones including _Zeuglodon Osiris_, _Eosiren
libyca_, _Barytherium grave_, Andr., _Moeritherium
Lyonsi_, _M. gracile_, Andr., _Gigantophis
Garstini_, Andr., _Pterosphenus Schweinfurthi_ and
_Tomistoma africanum_, Andr. The remains of a
siluroid fish are abundant; also _Propristis
Schweinfurthi_, Dames. Large numbers of
coprolites. Silicified wood 12
18. Brown sandy limestone with casts of shells,
_Akera_ aff. _striatella_, Lam., _Ampullaria_, n.
sp., _Gisortia gigantea_, Munst., _Lanistes
antiquus_, Blanck., _Melongena nilotica_, var.
_bicarinata_, _Mesalia_ sp., _Cassidaria
nilotica_, _C._ aff. _nodosa_, _Solarium_ aff.
_bistriatum_, Desh., _Alectryonia Clot-Beyi_,
_Cardium Schweinfurthi_, _Exogyra Fraasi_, _Lucina
pharaonis_, Bell., _Macrosolen Hollowaysi_, J.
Sowerby, _Meretrix nitidula_, Lam., _M.
parisiensis_, Desh., _Ostrea flabellula_, Lam.,
_Tellina_ sp., overlying clays with gypsum 4
19. Sandy limestone with numerous _Carolia
placunoides_ and _Turritella imbricataria_, Lam. 1
20. Greyish-blue and brown ferruginous, sandy, and
other clays. Plant remains 13
21. Friable shelly limestone with occasional small
calcite veins ½
22. Clays 4
23. Hard yellow sandy limestone with _Ostrea_ and
_Anisaster_ (_Agassizia_) _gibberulus_ ½
24. Clays with thin bands of fibrous gypsum 6
25. Hard friable shelly limestone with numerous
fossils, including _Dictyopleurus Haimi_, Dunc.
and Slad.; _Akera_ aff. _striatella_, _Turritella
carinifera_, _T. imbricataria_, _T. pharaonica_,
_Alectryonia Clot-Beyi_, _Arca tethyis_, Oppenh.,
_Cardita_ aff. _carinata_, J. Sowerby, _C._ aff.
_depressa_, Locard., _C._ aff. _triparticostata_,
Cossm., _C._ cf. _gracilis_ and _depressa_,
Locard., _Cardita fajumensis_, _Cucullæa_ aff.
_crassatina_, Lam., _Exogyra Fraasi_, _Glycimeris_
(_Pectunculus_) _pulvinatus_, Lam., _Ostrea_ aff.
_Reili_, _Spondylus ægyptiacus_, Bull. Newt.,
_Pecten solariolum_, May.-Eym., _P. moelehensis_,
May.-Eym., _Qerunia cornuta_, _Euspatangus
cairensis_, Loriol, _Linthia_ sp., _Anisaster
gibberulus_, _Schizaster_ aff. _africanus_,
Loriol; bryozoa ½
26. Sandy clays with gypsum 7
27. Friable, gypseous, impure limestone with _Exogyra
Fraasi_, _Carolia placunoides_, _Turritella_ sp.,
_Qerunia cornuta_, _Alectryonia Clot-Beyi_ ½
28. Sandy gypseous clays 3
29. Friable sandy limestone with _Carolia
placunoides_, _Exogyra Fraasi_, _Turritella_ sp.
(The ruin of Qasr el Sagha is built on this bed) 1
30. Gypseous sandy clays with occasional oyster-
limestone with _Qerunia cornuta_; ferruginous
sandstone band, etc. 27
---
Total 154
---
Hard grey sandstone with _Zeuglodon_ and numerous _Carolia_,
_Ostrea_, etc., in places, capping plain to south of Qasr el Sagha
and forming the top of the “Birket el Qurun series.”
The chief divisions of the series remain fairly constant and can be
recognized and followed for many kilometres westwards.[61] The lower
beds form the summits of Gar el Gehannem and the neighbouring hills
(see Fig. 2 and section p. 36), the upper beds of the series being
exposed in the higher escarpments to the north.
Although vertebrate remains are more common on some horizons[62] than
on others, they are occasionally met with in most of the beds. The
most prolific bone horizon is, however, about half-way down, i.e.,
those beds numbered 16 and 17 in the above section; bed 7 also yielded
a number of remains. At the point where the upper part of the section
was measured, 3½ kilometres north-east of Qasr el Sagha, the beds
16 and 17 yielded a considerable number of land-animal remains, all
of which occurred within a fairly confined space, suggesting that
they had been carried out from the land to this point by a strong
river-current and deposited when the latter became too feeble to
carry them further out to sea. The same beds were also examined in
the faulted bay 8 kilometres to the north, but no bones, or at most
a very occasional fragment or two, were obtained here. This is easily
explained by the greater distance of this locality from the land-mass
to the south. Westwards the same beds were always found more or less
bone-bearing, isolated detached mandibles, limb-bones and vertebræ of
_Mœritherium_, being of frequent occurrence, although no such complete
remains were found as those from near Qasr el Sagha. Reptilian and
fish bones are very widespread throughout the area. An extensive and
detailed examination of these beds over a large area can hardly fail
to yield important results, as other localities where skeleton-carrying
currents came out from the land would very likely be discovered.
That the Qasr el Sagha series was deposited in fairly shallow water at
no great distance from land seems certain, not only from the general
lithological character of the beds but from the number of land-animal
remains and the frequency of river and shore-frequenting whales,
dugongs, crocodiles and turtles. The clays, moreover, are found
to abound with impressions of plants, and in some cases are highly
lignitic, being made up of compressed masses of vegetation including
solid twigs, now found in a state more resembling charcoal than
ordinary dense lignites; some bands approximate to an impure brown
coal. In certain beds of the series further to the west, very thin
seams of true coal occur; they were, however, never seen to exceed one
or two millimetres. The intercalated bands of limestone are generally
impure and do not indicate any great conditions of depth, but only
rather a temporary cessation in the supply of sand and clay. Corals,
moreover, abound along many horizons.
[Illustration: PLATE IX.
UPPER BEDS OF FLUVIO-MARINE SERIES WITH BASALT CAP, LOOKING WEST FROM
THE EASTERN EXTREMITY OF JEBEL EL QATRANI.]