IOO 



PLATE LI. THE PRESSURE RIDGES AT CAPE CROZIER. 



FIG. 1. From a photograph taken by C. R. ROYDS (R. 154, 5" x 4" film), Oct. 18, 

 1902 ; looking eastward from the land-ice of the eastern extremity of Cape 

 Crozier, Ross Island. 



FIG. 2 (Map B). From a photograph taken by R. W. SKELTON (Sk. 191, ^-plate), 

 Oct. 18, 1902; looking S.-E. from the land-ice of the eastern extremity 

 of Cape Crozier, Ross Island. 



There are five great pressure ridges in the Barrier ice at Cape Crozier. In 

 each of the Figures here shown, the foremost ridge is that which abuts on the fast 

 land-ice, and the contrast between the moving ice and the stationary is evident. In 

 Fig. 1, for example, the camera was placed well back upon the land-ice, while the 

 figure which appears in the centre of the picture stands on the edge of the 

 stationary land-ice, looking down into a trough 20 feet deep, from the bottom of 

 which rises the first tumbled pressure ridge of the moving ice-sheet, to a height of 

 40 or 50 feet. 



In Fig. 2 the same contrast can be seen, while beyond the pressure ridges 

 the level surface of the Great Ice Barrier stretches away indefinitely to the S. and 

 E. Compare also Plate LII., which gives a bird's-eye view of these vast disturb- 

 ances, and some idea of their extent. They have been traced for more than fifty 

 miles, gradually increasing in magnitude from S. to N., but the climax of disturb- 

 ance is at Cape Crozier. 



