2O6 



PLATE CIV. THE PRAM POINT PRESSURE RIDGES. 



FIG. 1 (Map B). From a photograph by E. H. SHACKLETON (Sh. 167, ^-plate) ; 

 taken amongst the pressure hummocks of the Pram Point Ridges, Oct. 1902. 



FIG. 2 (Map B.) From a photograph by R. W. SKELTON (S. 14, 5" x 4" plate), Feb. 

 1904; looking N.-E. from the heights above Pram Point, over the pressure 

 ridges, to Mount Terror. 



The series of ice-waves shown in Fig. 2 lying parallel with the coast are caused 

 in the old sea-ice by some partial pressure transmitted from the Barrier movement, 

 into the channel between Ross and White Islands. 



The point at which these waves are truncated by a horizontal fissure marks 

 the limit of open water in 1902. When the sea was again frozen over, similar 

 pressure hummocks began to appear as waves in the ice, and continued to increase, 

 until, in two years' time, large sheets were standing upright as in Fig. 1. In 1904 

 the ice again broke up : its thickness was then 8 feet, the result of two years' 

 growth. 



See Nat. Hist. Rep., vol. i., pp. 59, 82; also, Scott, Voyage of the 'Discovery,' 

 vol. i., pp. 384, 394. 



