BONES NOT IN THE SOLID ROCK—RECENT BIRDS’ BONES. 155 
fissure, or cavern, formed by the disruption and subsidence of these 
masses, has been evidently filled up with this concretion, and is now 
exposed to full view, by the outward mass having dropped down, in 
consequence of the encroachments of the sea. It is to this spot that 
strangers are generally led to examine the phenomenon; and the 
composition having here attained to its greatest degree of hardness 
and solidity, the hasty observer seeing the bones inclosed in what has 
so little the appearance of having been a vacuity, examines no further, 
but immediately adopts the idea, of their being incased in solid rock. 
The communication from the former chasm, to the surface from which 
it has received the materials of the concretion, is still to be traced in 
the face of the rock, but its opening is, at present, covered by the base 
of the line-wall of the garrison. Here bones, apparently human*, are 
scattered among others of various kinds and sizes, even down to the 
smallest bones of birds. 
“ At the north extremity of the mountain, the concretion is ge¬ 
nerally found in perpendicular fissures; the miners there employed 
upon the fortifications, in excavating one of those fissures, found at a 
great depth from the surface two skulls (not human.) This concre¬ 
tion varies in its composition, according to the situation where it is 
found. At the extremity of Princes Lines, high in the rock which 
looks towards Spain, it is found to consist only of a reddish calcareous 
earth, and the bones of small birds, cemented thereby. The rock 
around this spot is inhabited by a number of hawks, that in the 
breeding season nestle here and rear their young; the bones in this 
* This error, as to the existence of human hones in this breccia, has been since 
corrected. 
x 2 
