1850.] Lead Mines of Kohel et Ter&feh. 219 



nace, for five successive days and nights. Lead (galena) is not only 

 found at the old excavations of Kohel et Terdfeh y but in several other 

 places in the eastern desert of Egypt, generally in short veins and 

 nests, in the limestone, as at "Wadi Araba, and the Mokattern. Old 

 lead mines are said to exist at Gebel Rassds, as before observed. 



T. J. N. 



Formation around Kohel et Terdfeh. 



Note. — The beds in this section are taken in the ascending order commencing 

 with the lowest. T. J. N. 



The formation in the plain (fersh) towards the N. W. of the Kohel 

 is composed of parallel layers of coarse, yellow, compact psammite, a 

 foot in thickness — succeeded by a layer, 4 or 5 inches thick, contain- 

 ing rolled pebbles of quartz, porphyry, granite, gneiss, &c. Seams of 

 crystallised sulphate of lime intercalate these layers ; and thin laminee 

 of the same matter branch through them vertically. Over them we 

 have several beds of yellow psammite tinged with red, and containing 

 nodules of oxidulated iron ; each bed averaging from 1^ feet to 2 feet, 

 in thickness. Several thin layers of gypsum, with intervening clays 

 and ferruginous psammites — about four inches thick in the aggregate, 

 and a layer, about eight inches thick, of calcareous sandstone — very 

 compact and hard — containing silicified bivalves in good preservation, 

 sufcceed. 



Overlying them is a series of light green and streaked psammites of 

 a less compact structure than the inferior beds — each layer is separated 

 from the other by an intervening seam of gypsum — about one, or one 

 and a half inch thick. 



Over these chloritic psammites we have a close arrangement of 

 parallel bands of gypsum, with intervening layers of disintegrated 

 clay (?) about twelve inches thick. Above them lies stratified sulphate 

 of lime of a compact nature from twenty to twenty-five feet thick, 

 with about seven or eight feet of a less compact sulphate of lime over- 

 lying it. Above the sulphates of lime we have a layer of corals : 

 and over the corals a diluvium composed of a dark yellowish marl ; on 

 which reposes a gravel of sharp angular fragments of granitic and 

 felspathic formations ; some of the fragments are a cubic foot in size ; 



