DESCRIPTION OF THE ISLANDS: COOK ISLAND 185 



The coast-line of the plateau on the southern and western sides is ever}^vhere steep 

 and rocky, and is formed as on other islands of black columnar basalt. The surface of 

 the plateau appears smooth and is probably overlaid with scoria and ash. The cliffs be- 

 tween Isaacson Point and Jagged Point are black, brown and red, and seem to be com- 

 posed mainly of tuff and ash : there are some fallen boulders on the narrow beach at their 

 base. Above Jagged Point a projecting spur forms an irregular knife-edge of curious 

 outline (Plate XXVIII, fig. 4) and the rock here is fine-grained and pale yellowish brown, 

 apparently a hard volcanic mud, with an underlying stratum of black basalt, visible at 

 the water-line. The lower cliffs on the north-east side are stratified with alternate layers 

 consisting apparently of tuff agglomerate and ash. 



Ringed penguins are very abundant on the island and have formed rookeries near the 

 shore at a number of points. On the north-east side, as already mentioned, small parties 

 of them were seen to have ascended the steep slopes of the cone almost to the brink of 

 the crater and to a height of at least 450 ft. above the sea. For a penguin such a journey 

 must be very arduous, and their object — unless it be to admire the view — is difficult to 

 understand. 



One or two patches of green vegetation were seen on the plateau and at several places 

 the snow was remarkably stained with reddish pink, yellow and yellowish green. The 

 first of these is the familiar " red snow ", caused by the unicellular alga Chlamydomonas, 

 and samples of it were collected on Thule Island. The yellow and yellowish green 

 patches were probably also due to algae, but of this it was not possible to be certain. 



There is no record of any landing on the island. 



Cook Island 

 Lat. 59° 26I' S ; long. 27° 09V W 



(Plates XXVII and XXIX ; Plate XXX, fig. i ; Fig. 20) 



This island is the largest and highest in the Southern Thule Group. It is rather 

 regularly oval in outline, but in the west there is a shallow bay which faces Douglas 

 Strait and is bounded at the south by Reef Point. Elsewhere only small projections 

 interrupt its even contour: Resolution Point^ in the north-east. Swell Point in the east 

 and Jeffries Point'- in the south. The island is nearly 3^ miles long and 2\ miles wide, 

 its longer axis lying east and west; in circumference it is 9! miles. It has three ice- 

 capped peaks, of which Mt Harmer,^ situated a little to the north of its middle point, 

 is the highest, having an altitude of 3660 ft. above sea-level. 



Cook Island is buried deep beneath an ice-cap (Plate XXIX; Fig. 20), and it is only 

 below the hanging glaciers and on headlands that the underlying rocks are visible. The 

 glacier follows the undulations of the rock beneath, and frequent ridges and protrusions 

 where the ice is crevassed indicate inequalities in the surface below, which have not yet 



^ H.M.S. 'Resolution', in which Cook circumnavigated the globe. 



^ Miss M. E. Jeffries, staff of the Discovery Committee. 



^ Sir Sidney F. Harmer, K.B.E., Sc.D., F.R.S., vice-chairman of the Discovery Committee. 



