220 Lieut. Newbold on the Geology of Egypt. 
are considered to be the remains of once continuous strata. The 
sandstone varies from a red, white or yellow compact rock to a 
loose quartzoze grit, with a calcareous, felspathic or ferruginous 
cement, and associated with it is a conglomerate composed of quartz, 
chert and jasper, derived chiefly from the subjacent limestone ; also 
beds of variously coloured marls containing gypsum and salt, and 
in which the natron beds of Egypt are situated. 
Casts of marine shells were noticed by Mr. Newbold in the vici- 
nity of Wadi Ansari, and trunks with smaller fragments of silicified 
trees occur in many parts of the Egyptian and Libyan deserts, par- 
ticularly in the Suez desert, seven miles east by south from Cairo. 
This district, called the ‘‘ petrified forest,” is described in great de- 
tail. It consists of a sterile irregular plateau, which is considerably 
above the level of the Nile, lying on the slope of the Mokattem range, 
and it extends three and ahalf miles southwardly, and four miles east- 
wardly. Many of the trunks are scattered over the surface among 
rolled and angular fragments of dark grit, and pebbles of jasper, 
chert, quartz and sharp-edged fragments of silicified wood. The 
largest trunks occur in the greatest abundance on or near dark- 
coloured knolls, particularly towards the south-east portion of the 
area, where they lie like broken stems of a fallen forest, crossing each 
other at various angles ; but the majority of the larger trees are di- 
rected towards the north-west. Two of the greatest, measured by the 
author, were 48 and 61 feet in length, and 24 and 3 feet in diameter ; 
but the lesser fragments are generally from 1 to 3 feet long, and 
4 to 12 inches in diameter. Among the fractured trunks which lay 
broken transversely on the sand-hills, Mr. Newbold noticed many 
with the edges sharp, and in nice adaptation, though the fragments 
were several feet apart. 
A few specimens are imbedded horizontally in the sand and asso- 
ciated conglomerate, and a still fewer occur in a vertical position 
rising from 12 to 20 inches above the surface. Mr. Newbold cleared 
the sand from one of these stumps, and ascertained that its lower 
part was imbedded in the subjacent conglomerate; but it exhibited 
no traces of roots. 
The trunks, which are rarely flattened and never invested with 
coaly matter, are branchless, and in general knotless ; though in some 
specimens Mr. Newbold traced places for the insertion of branches ; 
roots also are wanting, but among the masses enclosed in the sand 
some were found, which bore strong resemblance to the bulbous base 
of palms, and others which assimilated to the tortuous roots of exo- 
genous trees. Internally the trunks exhibit a concentric structure, 
though externally they resemble the present palms of Egypt. Some 
specimens examined by Mr. R. Brown were decided to be dicotyle- 
donous, and not coniferous; but one brought from the Nubian 
desert by the Rev. Vere Monro is stated to exhibit that structure. 
Indications of a jointed appearance are mentioned, but Mr. Newbold 
is of opinion that this calamite or reed-like structure may be due to 
contraction during the process of silicification. Instances of decay 
at the time the trunks were imbedded the author also noticed, the 
