60 "ALBATROSS'' TROPICAL PACIFIC EXPEDITION. 



southeast point (PI. 27), and at the southeast point these lines become broad 

 belts (PI. 28), deeply sunken, while to the south of it the cliffs, which now 

 are becoming less in height (PI. 29, fig. 2), are undercut mainly at the first 

 terrace, and the face of the cliffs is cut into prominent buttresses (PI. 28, 

 fig. 1). These gradually pass into the face of the second terrace of the south 

 point, where they crop out only here and there through the dense vegetation 

 (PI. 29, figs. 2, 3) and at the base of the first terrace ran across the slope of 

 the steep coral sand beach which separates them in the shape of wide wedges 

 (PI. 29, figs. 1-3) ; the base of these buttresses has to a great extent been 

 eaten away, or ground into coral sand. 



That the lines of caverns indicate the former lines of terraces is easily seen 

 in the passage of the vertical cliffs of the east coast, where the terraces are 

 only indicated by lines of caverns, into the terraces themselves (Pis. 27-29). 

 This is well shown at the southern point, where the line of the second and 

 third terraces gradually recedes from the face of the vertical cliffs and passes 

 into the walls of the terraces behind the talus indicating their base. The 

 mode of formation of the talus is also well seen along the south point, where 

 the first terrace is gradually eaten away and its material ground into a steep 

 coral sand beach. The sea, by breaking into the face of the cliffs of the first 

 teri'ace, forms a series of buttresses at right angles to the reef platform, be- 

 tween which run short sand beaches. As we approach the south point, the 

 buttresses become smaller and smaller, and the sand beaches longer, till the 

 first terrace only consists of a series of apparently independent buttresses 

 separated by sand beaches. 



The path back of the beach which leads from the centre of the west side of 

 Makatea across to the east face of the island runs in a great crevasse at 

 right angles to the trend of the bluffs. It finds its way up between high 

 walls rising on each side from 20 to 30 feet (PI. 30), until it reaches the 

 top of the bluff, where it enters a small canon with walls about 12 feet high, 

 running level for a distance perhaps of an eighth of a mile, then a gentle 

 descent begins into the sink occupying the central part of the island. The 

 sink falls away from the foot of the slope of the highest point at the north- 

 ern end of the island towards the south, where the lowest part of the sink 

 is fully 50 to 75 feet lower than the surrounding rim of the cliffs. The 



