Study of tht^ New York Obelisk as a Decayed Boulder. 107 



and etched surfaces of rounded boulders, near the level of the river : 

 Views from Philse to the N. and to the S. W., showing development 

 of columnar structure bj the decay, in the direction of the strike, 

 and formation of elongated boulders : Yiews of Philte from the E. 

 and from the S.W., showing the eroded columns of " Pharaoh's 

 Throne," rounded ledges, with hard seams (of quartz?) projecting 

 above the eroded surfaces, and huge exfoliating boulders.] 



These forms are so 'familiar to the geologist's eye, as character- 

 istic of rock-decomposition in a climate of heavy rainfall and winter 

 frosts, that it is at first hard to believe that these occur in one of 

 the most arid regions on the globe, where frost is unknown. The 

 topographical features suggest the probability that, throughout the 

 entire upper stratum of granite, to which the Egyptian quarrymen 

 were compelled to limit their exploitation, not exceeding a thickness 

 of 60 or 70 feet, the stone was already quite uniformly affected by a 

 kind of "dry rot." Further light on this matter will be presented 

 beyond, in physical tests made on the freshest stone I have been 

 able to procure from the Assouan quarries. 



To Yilliers Stuart^ we owe an archieological observation at the 

 First Cataract, whose geological importance seems to have been 

 overlooked: "We landed at the island of Schael, just below the 

 falls, to examine the inscriptions on the rocks ; they are very 

 numerous and curious, and extend over a period of 2000 years. 

 The earliest we saw was of Ousertasen the Third, of the Xllth 

 dynasty (2200 B. C, Lepsius) . . There is a special interest about 

 Ousertasen's, for it was inscribed while the Nile was still at its 

 original level, 23 feet higher than now ; and accordingly it stands 

 high upon the rocks. . . . They are all cut in granite, and Ouser- 

 tasen's showed its great age by the fact that a process of decay in 

 the granite itself had set in, the once polished surface being corroded 

 and eaten by the tooth of time, and the outlines somewhat blurred. 

 High up among the loftiest rocks of the island, however, I found 

 another inscription and a statuette cut in bold relief in a niche 

 which must have been much older even than Ousertasen ; the 

 granite had so entirely decayed that the features of the statue had 

 dissolved and were undistinguishable. There were manv lines of 

 hieroglyphics in like manner quite decayed and illegible. No clue 

 therefore existed to the date except the condition of the stoue, 



• Nile Gleanings, 203. 



