286 SIR WILLIAM DAWSON, C.M.G., LL.D V P.E.S., 



hood, where the whole surface of the ground there is rich with the 

 most beautiful f oirnis of agate and cornelian . 



Professor J. Logan Loblby, F.Gr.S. — There is one point which T 

 may throw some light on, as to there being actual alabaster in 

 Egypt. Professor Hall has rightly held that the alabaster that 

 Sir Wm. Dawson mentions is now called "limestone stalactite." 

 It was originally called alabaster, from the Arabic word alabastron, 

 but it is not now so called. The original alabaster was a substance 

 similar to the onyx stone, that is, carbonate of lime ; but what we 

 now call alabaster is sulphate of lime, and banks of that have 

 been found in Egypt. As to the Nubian sandstone, I observe that 

 Sir William Dawson says its age probably ranges from Permian to 

 Lower Cretaceous. 



Mr. W. H. Hudleston, F.R.S., President Geol. Soc. — I suppose I 

 should say a few words. We owe a great deal to Sir Wm. Dawson 

 for his information on the rocks of Egypt. There is one difficulty 

 with regard to these rocks, and that is that you find there are 

 such large numbers and varieties of this gneiss rock associated 

 with diorite and granite and so forth. There are not many 

 rich mineral veins there. We do not hear of many minerals 

 produced from Egypt — in fact, Egypt though rich in stone seems 

 to be poor in metallic minerals. 



The question of the Nubian sandstone, as Professor Hull knows, 

 is one that concerns a wide area, and few have done more than 

 Professor Hull himself in settling what that formation represents 

 in the Sinaitic Peninsula — that it is in part Carboniferous, whilst 

 the upper portions are probably of Cenomanian age. With 

 reference to the masses of Siliceous rock in more recent deposits 

 such as those of the Mokattam hills, the Author says : — " That 

 this is the origin of the hills is evident from the nearly horizontal 

 position of their layers, from their containing silicified wood so 

 distributed and with its cracks filled by sandstone, &c, so as to 

 show that it was embedded in the natural state, and afterwards 

 silicified, and by the irregular pipes or craters passing through 

 the hardest parts of the beds, and appai-ently the channels of 

 geysers or fountains of heated water." He then proceeds to say 

 that there is no evidence of such action in that neigbourhood — I do 

 not suppose there is likely to be ; in fact, I am myself inclined to 

 think this formation may more probably be the result of the action 

 of cold rather than hot water. Possibly Professor Hull will be 



