2. Commonwealth Bay Survey 



The track chart of the detailed survey that was conducted in Common- 

 wealth Bay from 19 to 21 February 1962 Is presented as Figure 67. Sufficient data 

 were collected on this survey to construct bathymetric and magnetic contour charts 

 of the area (Figs. 68 and 69). The irregular bathymetric relief of the area appears 

 to have no pronounced trends. Attempts made to obtain bottom samples indicated 

 that the area has little or no sedimentary column. The only samples obtained were 

 of sponge spicules and float. A crater cone was located at approximately 66® 49' S, 

 143* 08' W. 



The magnetic field in the area also is irregular with large anomalies. 

 These anomalies In general show very poor correlation with the bathymetric fea- 

 tures. Estimates of the depths to the magnetic sources, however, correspond 

 very closely with depths to the floor of the bay. This indicates that there is little 

 or no sedimentary cover over the magnetic source rock. Rock samples collected 

 from out -crops on shore were metamorphic rocks in which magnetite Is a common 

 accessory mineral . 



The indication that very little, if any, sedimentary cover Is present over 

 the magnetic source rock, combined with the lack of correlation between bathy- 

 metric and magnetic features, infer that the submarine topography In the Common- 

 wealth Bay area is the result of glacial scouring. The large magnetic anomalies 

 In the area are probably caused by magnetic susceptibility contrasts in the source 

 rock . 



79 



