§ 42. RECENT LIMESTONE OF THE BERMUDAS. 85 



detritus is blown inland by the winds, and is soon con- 

 solidated by the percolation of water, and the infiltration 

 of crystallized carbonate of lime ; a fine white calca- 

 reous stone is thus formed, which in some localities is 

 sufficiently compact for building. In this rock are nu- 

 merous shells and corals, of species which inhabit the 

 neighbouring seas; in some instances the large mottled 

 trochus, so well known to collectors both in its natural and 

 polished state, with all its colours preserved, is imbedded 

 in a pure white limestone. In many specimens the colours 

 are faded, and the shells very much in the state of those 

 found in the tertiary strata at Grignon ; in others the shelly 

 matter is wanting, but the hard stone retains the forms and 

 markings of the originals. The corals are imbedded in a 

 similar manner ; and masses occur in the limestone so like 

 the fossil corals of the oolite of this country, that it requires 

 an experienced eye to detect their real nature. 



In a suite of specimens, showing the transition from 

 loose sand to solid rock, we have — 



1. Broken shells and corals, retaining their colours. 



2. Similar materials, more comminuted and completely bleached. 



3. An aggregation of fine sand and white earth, broken shells, and 



corals. 



4. Friable limestone, resembling soft chalk, and composed of com- 



minuted corals, &c. 



5. Hard limestone, of similar materials. 



6. Compact limestone, enveloping shells and pebbles. 



7. A fine indurated limestone, so hard as to be with difficulty broken 



by the hammer, inclosing a few shells and corals: this stone is 

 employed for building.* 



* On this bare calcareous rock the coffee-plant finds sufficient sup- 

 port, and is seen in many places growing luxuriantly, its stems shoot- 

 ing out from between the crevices of the stone. In the botanic gardens 

 at Kew arc several coffee-plants from Bermuda, growing on blocks of 

 this rock. 



