18 



MAEION EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



A Crack in pack 



FicuKE 7. — Winds and currents often open cracks in the pacls ice such as shown 

 here. A crack differs from a lead in respect to its width, a crack not heing of 

 sufficient width to permit navigation. A crack Is the antithesis of a pressure 

 ridge. (Photograph by 11. G. I'onting in the Scientific Reports of the British 

 Antarctic Expedition.) 



A Lead 



Figure 8. — A lead in pack ice. Ships In the pack are conned b.y the ice navigator 

 from a station aloft. This Is the best vantage point to study the system of leads 

 and the location of open water. (Photograph by H. G. Pouting in the Scientific 

 Reports of the British Antarctic Expedition.) 



