Quart. Journ. Geol. Soc. Vol. LXVII, Pl. XVI. 



FIG. 1.— BLOCK OF GRANITE FROM THE UM ESH RANGE, SHOWING THE 

 FRETTING AWAY OF FELSPARS, THE OUTSTANDING QUARTZ, ETC. 



A. W. Phot 



FIG. 2.— ARROWHEAD TWIN OF GYPSUM FROM JUBAL ISLAND, SHOWING 

 THE MECHANICALLY ETCHED FIGURES. 



A. IV. Photo. 



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