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HUDLESTON: GEOLOGY OF PALESTINE. 
4. Kochs older than the Cretaceous Limestones. — We must of course 
begin with the crystalline rocks, of which granite is the most 
important, but with it are associated those porphyries, which in the 
Egyptian granitic region have yielded such fine building stones. 
The mountainous core of the Sinai Peninsula, including- all the 
great ranges before mentioned, consist of some variety of granite, 
and it is evident that red felspar granites are the most abundant, 
and characterize the region by the colour which they impart to the 
rocks. We obtain our best account of the physical aspect of this 
region, and of the peculiar features produced by granite and its 
associated rocks from the pen of the late Professor Palmer.* 
This lamented author ascended most of the principal granite 
mountains, such as Jebel Mousa, Jebel Katherina, &c., and brought 
away specimens of the rocks ; some of which by the kindness of 
Professor Bonney I have been able to inspect. 
Koch Specimen 1 . — Let us begin with the summit of Jebel 
Katherina. This is a syenitic granite of a peculiar nature : in a pinkish 
felspar base, which occupies the bulk of the mass, are small crystals 
of orthoclase, quartz, and hornblende. The quartz is not insterstia^ 
as in the more typical granites. 
Koch Specimen 2. — Jebel Musa. This is from Mount Sinai itself, 
and is a mixture of coarse red felspar and grey vitreous quartz* 
There is very little trace of any third mineral, so that the rock 
nearly approaches a pegmatite. 
Koch Specimen 3. — Summit of Serbal. This is a more thorough 
pegmatite than the other, and in better condition ; the felspar is a 
bright red. The two last specimens arc very typical of the 
granites of the Sinai Peninsula. 
Serbal is especially remarkable for the number of diorite dykes 
which traverse the softer granite, and project like so many teeth, 
according to Dr. Fraas, from the ridge forming the summit of 
the mountain. The serrated aspect which one sees in pictures may be 
due to this cause. 
We obtain a considerable amount of information relative to the 
granites of this region from Professor Milne, who accompanied the 
* Desert of the Exodus, vol. I., p. 27, 
