180 CORALS AND CORAL ISLANDS. 
Below, it had been worn like the one just described, though 
to a less extent. Another similar mass was eight feet high. 
Figure 2 represents a block six feet high and ten feet in its 
longest diameter, seen on Waterland; it was unattached be- 
low, and lay with one end raised on a smaller block. On 
Aratica (Carlshoff), others were observed. One loose mass 
like the last was eight feet high and fifteen feet in diameter, 
and contained at least a thousand cubic feet. Raraka also 
afforded examples of these attached and unattached blocks, 
some standing with their tops six feet above high-water mark. 
These masses are similar in character to many met with 
among the fields of blocks just described, and differ only in 
having been left on the platform instead of transported over it. 
Some of them are near the margin of the reef, while others are 
quite at itsinner limit. The second mass alluded to above, on 
Kawehe, was a solid conglomerate, consisting of large fragments 
of Astreeas and Madrepores, and contained some imbedded 
shells, among which an Ostrea and a Cyprea were noticed. 
This is their usual character. The other two were parts of 
large individual corals (Porites); but there was evidence in the 
direction of the cells that they did not stand as they grew; on 
the contrary, they had been upthrown, and were afterward 
cemented with the material of the rock beneath them, probably 
at the time this rock itself was consolidated. Below some of 
the loose masses the platform was at times six inches higher 
than on either side of the mass, owing to the protection from 
wear given to the surface beneath it. These blocks are always 
extremely rough and uneven, like those of the emerging land 
beyond; and the angular features are partly owing, in both 
cases, to solution from rains and from the dashes of sea-water 
to which, with every tide, they are exposed. 
It should be distinctly understood that these masses here 
