Figure 2-1 3. — Hudson Bay area. 



Along the shores of Hudson Bay and Strait the ice begins to form 

 about late October and builds outward to a distance of 5 to 7 miles. 

 The thickness of the ice varies. In protected inlets the ice usually 

 is about 5 feet thick as a winter maximum. Outside these shel- 

 tered places the ice is subject to the effects of storms which may 

 raft the ice to thicknesses of 15 to 20 feet. By November the en- 

 trance to Hudson Strait is blocked by pack ice, and although the 

 Strait does not freeze from shore to shore the center of the channel 

 is filled by pack ice moving both east and west with the currents. 

 By the end of June the ice begins to break up and drift toward 

 Hudson Strait, thus clogging the channel during most of July. 

 The Bay and Strait are usually open to navigation during late July, 

 August, September, and October, depending on the direction of the 

 prevailing winds. Early November again sees this area being cut 

 off from outside surface communication as the sea-ice begins to 

 form. 



TOPOGRAPHY 



Underlying most of this area are pre-Cambrian rocks of the 

 Canadian shield, with a belt of sedimentary rocks extending 

 through the central arctic islands and including most of the far 

 northern and western islands. Erosion and weathering of the 



42 



