MAKEMO. 101 



its further decay and disintegration ; at the same time soldering adjoining 

 pieces into a compact paving which eventually forms the great shore reef 

 flats and shoals of the lagoon of an atoll. Or the corallines grow in huge 

 masses on the bottom of the lagoon, and when dead and disintegrating 

 cover the floor of the lagoon with a viscid calcareous mass which, mixed 

 with fragments of shells and other invertebrates or pieces of dead coral, 

 makes a recent fossiliferous mass resembling more or less coarse chalk. 



On the northeast face the islands are narrow (PI. 60, figs. 1, 2) ; the 

 land rim is generally not more than 500 to 600 feet in width ; the 

 beaches are steep (PL 59). All along the sea face shores of the Paumotu, 

 where we find high coral sand beaches the boulders and shingle have been 

 completely ground to pieces, and the old ledge is well cleaned and left 

 exposed on the reef flat platform (Pis. 62, fig. 2 ; 65, fig. 1) ; where shingle 

 predominates there are usually lines of boulders at the foot of the shingle 

 beach, covering the reef flat in part (PI. 59, fig. 2) ; and where there are 

 masses of large boulders the land rim is low, the material for elevating it 

 to the height of the rest of the land rim, either as a coral sand or a shingle 

 beach, remaining piled up in masses of boulders along the low line of reef 

 flat or upon the old ledge reef flat (PI. 62). 



On the northeast face of Makemo the outer platform is narrow. The 

 outer edge is protected by masses of highly colored Nullipores and Pocil- 

 lipores (Pis. 59, fig. 1 ; 60, fig. 2 ; 62, 63). The northeast shore is protected 

 b}' narrow shingle beaches (PI. 62) and small masses of beach rock. There 

 are long reaches of this, forming a sort of hedge of beach rock and of recent 

 conglomerate boulders (PI. 63, fig. 2) in the rear of the narrow reef flat of 

 the old ledge, of which an outcrop runs here and there across the beach and 

 is lost in the mass of the outer belt of vegetation (PI. 64). For a long dis- 

 tance the land rim consists of long narrow islands edged by a coral shingle 

 beach from five to six feet high (Pis. 59, fig. 2 ; 62) ; and as we pursued our 

 course the outer shingle beach gradually' increased in height to seven or 

 eight feet, and in some places to nearly ten feet. There is no lee on the 

 northeast side of Makemo ; the whole shore is raked by the trades. 



The high sliingle beach stretch is followed by a low coast protected by 

 a ledge wall and masses of boulders. Here and there a small island covered 



