ANDREWS: LIMESTONES OF THE FIJI ISLANDS. 29 



although in places 30 and 40 feet deep, have not altered materially the 

 original contour of the summit. 1 



Observations taken in the Windward Isles of the Group show a 

 remarkable similarity in this slope. Many of the angles of inclination 

 to the horiton of the limestone bluffs averaged 50° to 55°, with a final 

 100 feet of steeper slope. This top part might go even higher than 75°. 

 The truncated " sugar-loafs " are a topographical feature perfectly unmis- 

 takable (Plate 27). 



On examining these slopes closely, they are found to consist of black- 

 ened and weathered needle-like formations. The minute ridge-structure 

 mentioned before is developed to such a degree as to render climbing up 

 the steep faces dangerous, owing to their being so worn away as to yield 

 to the slightest touch in places. 2 Struck with a hammer, these eroded 

 blocks, of perhaps five hundredweight, and attached to the rock mass by 

 a column only one or two inches in diameter, ring like bells, and a very 

 slight blow is often quite sufficient to send them crashing down the hill 

 to the debris heap below. Notwithstanding this weathering, the re- 

 mainder still marvellously preserves the original contour of the reef as 

 it rose from the waters. 3 



At the base of these escarpments great talus heaps accumulate. These 

 were formed, apparently, in many cases, under submarine conditions. 

 The base assumes a less highly pitched angle of slope than the upper 

 development. Furthermore, denuded of its debris covering, the basal 

 rock, projecting here and there in rocky ribs, possesses a less slope than 

 the upper part. 



Again, the angle of inclination may exceed 80°. Then the cliff varies 

 altogether. It is no longer black, but more commonly assumes a yellow- 

 ish-white or brown color, and the face is encrusted with secondary cal- 

 careous material. This veiling of the cliff face hides otherwise easily 

 determinable characteristics of the limestone. Some few of these per- 

 pendicular exposures are most likely due to rupture subsequent to 

 upheaval. But this is exceptional. At the north of Mango are three 

 cliffs (Plate 9) close together, 300 feet above the talus, and so conspic- 

 uous as to constitute landmarks far out to sea. At the base of one of 



1 For a statement of the opposite view see A. Agassiz. /. c, p. 74, and Am. Jour. 

 Sci., Jan., 1900, p. 42 ; ib. Feb., p. 110; ib. March, p. 196; ib. May, p. 372. 



2 See A. Agassiz, I. c, Plates 97, 98. 



3 I think Mr. Andrews is mistaken. The immense amount of denudation which 

 has taken place in the Fiji Islands and other elevated reef islands in the Pacific 

 I have examined shows that the original reef slope is not preserved to any extent- 

 It has usually been greatly obliterated by denudation and erosion. — A. Agassiz. 



