224 



MR. JTJKES-BKOWNE AND PEOF. HAEHISON 



embedded in coral-sand and debris. It is sometimes a breccia or 

 boulder-rock, sometimes a rubble-rock, and sometimes a calcareons 

 sand-rock. 



§ 4. Analyses of Coral-eocks. 



Tbe following are analyses, made by one of ns in the Government 

 laboratories of Bridgetown (Barbados) and Georgetown (British 

 Gniana), of seven specimens of coral-rock. The first was a loose un- 

 consolidated rock from an excavation near Bennetts, at a level ot 

 about 400 feet. The next three were specimens obtained tor us by 

 Mr. Easton from a shaft in Plumtree Gully, east of Endeavour, the 

 surface-level being about 680 feet : Nos. 1 and 2 were from a depth 

 of about 45 feet, and No. 3 from 30 feet down; ^o. 1 had a 

 brownish tint. The fifth sample was part of th .it sent by Mr 

 Piggott from the well at Ellis Castle, taken from a depth of 130 feet 

 from the surface-a rather hard white rock. The sixth was a piece 

 of the hard white limestone with tubular cavities described on 

 p. 215. The seventh was a similar hard limestone taken from near 

 the surface by the road south of Castle Grant. 



S 5 



Calcium carbonate 



Magnesium carbonate ... 



Calcium phosphate 



Iron peroxide and alumina 



Sihea and clay 



Loss on ignition 



Plumtree Gully. 



(D 



No. 1. 



95-78 93-38 



201 



trace 



2-27 



•05 



100-11 



2-05 

 •05 

 •78 



3-10 

 •70 



No. 2. 



i^ 



No. 3. 



96-52 

 1-74 



trace 

 •64 

 1-20 



100-06 



10010 



99-01 

 •56 

 •13 

 •35 

 •20 





100-25 



9809 

 1-25 



-07 

 •27 



•48 



100-16 





98-80 I 97-26 

 •87 1 2-44 



trace , trace 

 -19 -17 

 •29 ' -13 



10015 10000 



The following is an analysis of a soft white fine-grained mud or 

 marl from the base of the coral-rock near Codringtou :— 



Calcium carbonate ^t ?? 



Magnesium carbonate 1'1| 



Calcium phosphate '^j 



Calcium oxide '"*i 



Iron and alumina '^^ 



Silica and clay [^^ 



Loss on ignition '^^ 



100-45 



