232 APPENDIX. 



observed upon the sandstone, but these depositions were so 

 partial, and in all cases the ground was so much overgrowTi 

 with bushes, that we were unable to examine their charac- 

 ters with any degree of minuteness. This striking differ- 

 ence, however, we observed, and we are led to consider it as 

 constant, that the inferior limestone, wherever it appears 

 exposed, is covered with small scales or fragments of the 

 hornstone nodules whose existence has already been alluded 

 to, while none of the flat calcareous fragments, abounding in 

 shells, are found upon it ; whereas these were uniformly 

 observed to the exclusion of the scales of hornstone upon 

 the surface of the calcareous stratum that overlays the sand- 

 stone." 



Mr. Keating gives the following further account of his 

 examination of the St. Peter's : — 



" The bluff upon which the fort is built offers a good oppor- 

 tunity for observing the geological structure of the country. 

 It consists of several strata, all disposed in parallel and hori- 

 zontal superposition. On the surface of the ground blocks 

 of limestone are found, which appear to be the remains of a 

 stratum that has, in great measure, disappeared. These are, 

 in most cases, of a compact and earthy texture, destitute of 

 any organic remains, exhibiting occasional specks of a crys- 

 talline nature, which are observed to be calcareous, as, not- 

 withstandmg their small volume, they present a distinct 

 rhombohedral cleavage. The first stratum which is observed 

 is about eight feet thick. It is formed of limestone, present- 

 ing a very distinct slaty stmcture. The texture of the rock 

 is compact, its fracture splinteiy and uneven. Organic 

 remains abound in it. These are, as far as we saw, exclu- 

 sively producti. They lie in the rock as thick as possible. 

 A small vacant space is generally observed between the inner 

 and the outer casts of the sliell. This is, however, generally 



