106 



MARIOIs^ EXPEDITION TO DAVIS STItAIT AXD BAFFIN BAY 



ICEBERG With an Arch 



FiGUKE 67. — Occasionally itebergs are observed in the western North Atlantic pierced 

 by a large hole or bore through which the waves continually surge and spout. 

 Such holes or bores develop from the gradual enlargement of a slight depression 

 or embayment. Caves are developed by waves in a fashion similar to those along 

 the sea cliffs on shore. (Photograph by Lieut. Commander N. G. Ricketts. ) 



The -Twin' berg 



FuiURE 68. — A moditieation of the ordinary "dry dock" or " vallry ' shaped Imm l; 

 is the type shown here. Such ice is soiui'timi's reported by vessels at sea as t\\ • 

 bergs or twin bergs. It, however, is simply one berg tliat has 1)een disiiitegrateil 

 by wave action until the mid section has retreated below the surface of the sea. 

 The U. S. Coast (iuard cutter Tampa eaii be seen through the gap. standing iiy 

 the berg, warning liy radio all approaching steamships. (Official ph'otograpb. 

 international ice patrol.) 



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