316 PROFESSOR E. HULL, LL.D., T.R.S., F.G.8., ON THE 
specially mentioned the colossal statues of the Memnium at 
Thebes, it was called by De Roziére the “Monumental Sand- 
stone.’* 
This rock consists of red and variegated sandstone several 
hundred feet in thickness, and is destitute of fossils, except 
plants. Where it rests upon the old erystalline rocks it 
becomes a breccia, or conglomerate ; in fact it constitutes a 
beach or shore bed, made up of pebbles derived from the 
original floor and bordering uplands of crystalline rocks. 
Red sandstone occupies large areas in Nubia, and Middle and 
Southern Sahara.t It is also found in Arabia Petrea, and 
along the eastern slopes of the Arabah Valley and shores of 
the Dead Sea. Its geological age has been long a subject 
of discussion amongst observers and travellers in the East, 
and it has been referred successively to the Cretaceous, 
Triassic, Permian, and Devonian ages. It is now known 
that it belongs in part to two geological periods widely 
separated, viz.: the Lower Cretaceous and the Lower Car- 
boniferous. The discovery of limestone strata with Carboni- 
ferous marine fossils, within the mass of the red sandstone 
in the Wady Arabah, near the western shore of the Red 
Sea, by Schweinfurth;{ in the Wady Nasb, in the Sinaitic 
Peninsula, by Bauerman;$ and to the east of the Dead 
Sea by the author, shows that the lower portion at least 
is in some places Carboniferous, or older; while the upper 
strata, passing as they do into the Lower Cretaceous 
series and conformably stratified therewith, indicates that 
these beds are of Cretaceous age. It is probable that the 
Carboniferous sandstones are only local; and that more 
generally the greater mass, including that in the Nile Valley, 
is of Cretaceous age. To the lower (or Carboniferous) 
division I have given the name of “The Desert Sandstone,” 
to distinguish it from the upper or Cretaceous division, to 
which the name ‘Nubian Sandstone” properly belongs.|| 
It is not improbable that the Adigrat sandstone formation of 
* “ Grés Monumental,” which happily avoided any theory regarding 
its geological age. De Roziére, “ Description de ’Egypte,” Hist. Nat., 
dls 
+ Zittel, loc. cit., p. 41. The red sandstone of the Ahaggai Mountains 
is considered by Zittel to be Paleozoic. 
t “Sur une récente Exploration géologique de ’Ouadi Arabah,” Bull. 
del Institut Egyptien, 1887. 
§ Quart. Journ. Geol. Soc., vol. xxv., p. 27; also “ Geol. Arabia Petra 
and Palestine,” Mem. Pales. Exploration Fund, p. 44. 
|| Zbid., p. 45. 
