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



FIG. 1.— COARSE SAND WITH MINIATURE ' DREIKANTER," FROM THE PLAIN BETWEEN 

 THE UM ESH AND THE JEBEL ZEIT RANGES: NATURAL SIZE. 



A. W. Photo 



FIG. 2— WHITE LIMESTONE-CLIFFS. JUBAL ISLAND. SHOWING THE EFFECT OF 

 WIND-BLOWN CALCAREOUS SAND UPON JOINT-PLANES. 





4 



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!. W. Photo. 



Bemrose Ltd,, Co//o., Derby. 



