106 



MARIOX EXPEDTTIOX TO DAVIS STRAIT AND BAFFIN BAY 



ICEBERG With an Arch 



FiGUKE 67. — Octasioually icebergs are observed in the wesleni Nortli 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 cliflfs on shore. (Photograph by Lieut. Commander N. G. Ricketts. ) 



The -Twin' Berg 



FiGUKE 6S. — A modification of the ordinnry •" dry dock " or •' valley " shaped berg 

 is the type shown here. Such ice is sometimes reported by vessels at sea as two 

 bergs or twin bergs. It, however, is simply one l)erg that" has been disintegrated 

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

 The U. S. Coast Guard cutter Tampa can be seen through thi^ gap. standing by 

 the berg, warning by radio all approaching steamships. (Official ph'otograph, 

 international ice patrol.) 



