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SKEATS : CHEMICAL COMPOSITION OF LIMESTONES. 59 
consolidated volcanic mud derived from the subjacent volcano, and 
mixed with calcareous organisms such as Foraminifera. This was 
usually succeeded by foraminiferal limestones composed of calcium 
carbonate to the extent of 75 to 85 per cent, the remainder consisting 
of ‘insoluble matter. Raised coral reefs were found by him resting 
either on the foraminiferal limestones or on the volcanic muds. 
Although some of the larger islands have been elevated as much as 
10,000 feet, Mr. Guppy never found the raised reefs above the level of 
600 feet, and they were never more than 150 to 200 feet in thickness. 
Most of the analyses, made for Mr. Guppy by Dr. Leonard Dobbin, 
were of the volcanic muds, but two analyses of coral limestones were 
added. In one from the Shortland Islands the amount of calcium 
carbonate was 95.76 per cent ; the remainder, 4.24 per cent, consisted 
of insoluble residue. Another specimen from Choisel Bay gave, on 
analysis, 94.19 and 5.81 per cent of calcium carbonate and insoluble 
residue respectively. 
In a paper read before the Geological Society, in 1891, Mr. Jukes 
Brown and Professor Harrison’ gave a description of the geology of 
‘Barbados. They stated that no volcanic rocks occurred, that there 
was no evidence of subsidence, that six sevenths of the surface of the 
island were covered with coral rock, having a maximum thickness of 
260 feet, and that terraces occurred up to a height of 1100 feet. 
The following are the results of nine analyses of some of the raised 
coral limestones : — 
: e - Ferric “1: 
Calcium Magnesium Calcium = Silica Loss on 
Carbonate.| Carbonate. | Phosphate. ace and Clay.| Ignition. Total, 
trace ; ‘ 100.11 
05 : ; 5 100.06 
== 3 : 100.10 
13 F : 100.25 
07 : : 100.16 
trace : : 100.15 
trace : : 100.00 
100.45 
100.14 
I. Marl near Bennett’s, 400 ft. VI. Grove’s hard limestone. 
II. 635 ft. VII. Castle Grant limestone. 
III. 635 ft. }Plumtree Gully. VIII. Base of coral rock near Codrington. 
IV. 650 ft. IX. Crystalline concretionary rock from shaft 
Y. Ellis Castle Well, 130 ft. from the surface. at Cane Garden. 
1 Q. J. G.S., 1891, pp. 197-246. 
