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1. Marine. Calcareous matter predominating. 
Formed chiefly by animals. 
Encrinital limestone. 
Coral limestone. 
Foraminiferal limestone. 
Shell limestone. 
Polyzoanal limestone. 
Hydrocoralline limestone. 
Formed chiefly by plants. 
Nullipore limestone (oolites). 
More or less siliceous in composition. 
Diatom limestones. 
Radiolarian limestones. 
Poriferan limestones. 
2. Sweet-water limestones. 
Shell marls. 
Chara limestones. 
Indusial limestones. 
(b) Chemical agencies more prominent than the organic. 
1. Deposits in Saline waters. 
Lagoon deposits. 
Lacustrine limestones. 
B. Terrestrial. Mainly of chemical origin. 
1. Calcareous deposits from springs. 
(a) Travertine, &c. 
(b) Stalagmite and stalactite. 
C. Subterranean. 
1. Infiltration products. 
2. Results of concretionary action. 
3. Extrusions resulting from the liberation of lime 
during the transmutation of one silicate into 
another; e.g., when augite is transmuted 
into hornblende or into biotite. 
D. Dolomitized, ferrified, silicified, marmorized, or other later 
modifications of any of the foregoing. 
