352 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
The whole presents a blacker aspect than the surrounding desert, 
caused, as we found subsequently, by the ferruginous character of the 
- grit and conglomerate forming these knolls, im which much of the 
silicified wood lay partially imbedded, the ends protruding from the 
superjacent sand. The sandstone, in one specimen presented to the 
Society, exhibits marks of marine shells, which from the cireumstance 
of their being casts, and those in the subjacent limestone being casts 
also, cannot have been derived from the limestone, an observation for 
which I am indebted to Mr. Lonsdale. 
Many of the trunks he scattered loosely over the surface, amid 
rolled and angular fragments of the dark grit, pebbles of jasper, chert, 
quartz, and sharp-edged bits of silicified wood; but they were not in 
so perfect a state of preservation as the imbedded trunks. The site 
which they occupy slopes gradually in a southerly direction towards 
Wadi et-Tih, and is drained by the shallow channels previously men- 
tioned, which run into a ravine following the general slope of the 
land: at the time of our visit they were perfectly dry. The prospect 
is bounded to the south by the low calcareous ridge that skirts the 
valley of Et-Tih, separating it from the wastes of Baccara, and runs 
westerly to the Nile. To the east lies the monotonous expanse of the 
Suez desert ; to the west the mural limestone ridge of the Mokattem ; 
and to the north the valley separating the petrifaction-bed from the 
once continuous stratum forming the sandstone heights of the Red 
Mountain (Gebel Ahmar). 
The largest trunks are seen in the greatest abundance on or in the 
vicinity of the scattered knolls, particularly towards the south-east 
portion of the area, where they lie, like the broken stems of a fallen 
forest, crossing each other at various angles. The majority of the 
larger trunks had a north-west direction. Two of the largest ob- 
served measured, severally, 48 and 61 feet in length, and 23 and 3 
feet in diameter. They resemble in external aspect the present palm 
of Egypt, but internally the wood has the annular concentric struc- 
ture of exogenous stems, A few exhibited, externally, longitudinal 
fibres intersected, at intervals from two to three feet asunder, by 
transverse divisions, giving the trunk the appearance of a gigantic 
Calamite, although the internal structure is that of dicotyledonous 
wood, and is pronounced by Mr. Robert Brown, who kmdly examined 
the specimens, not coniferous. One of these trunks had a cireum- 
ference of thirty inches. The jointed appearance it is possible may 
have been caused by contraction during the process of silicification, 
but may it not be the original structure of a tree now no longer 
known? The greater portion of the trunks visible lie scattered loosely 
in and on the sand and gravel, in broken fragments from 1 to 3 feet 
long, and from 4 to 12 inches in diameter. A few are yet seen im- 
bedded horizontally in the sand and pudding-stone, and. still fewer 
preserve a vertical position, not rising higher than from 12 to 20 inches 
above the present surface of the sand. From one of these stumps I 
cleared away the sand and gravel, as far as was practicable with no~ 
better instruments than a hammer and my hands, and clearly traced 
it to the subjacent pudding-stone in which it stood imbedded. No 
