xviii CONTENTS 



CHAPTER XXIII 



CALCAREOUS FORMATIONS, VOLCANIC MUDS, PALAGONITE-TUFFS 



General Character, 317. — Coral Limestones, 318. — Foraminiferal Limestones, 

 319. — Pteropod-oozes, 320. — Foraminiferous Volcanic Muds, 321. — Samples 

 322. — Altered kinds, 324. — Submarine Palagonite-tufifs of mixed composi- 

 tion, 326. — Samples, 330. — Altered Basic Tuffs, 332. — Submarine Basic 

 Pumice Tuffs, 333. — " Crush-tuffs " formed of basic glass and palagonite, 

 334. — Zeolitic Palagonite-Tuffs, 334. — Palagonite-marls, 335. — Acid Pumice 

 Tuffs, 336 Pages 2,^7— ZZ(> 



CHAPTER XXIV 



PALAGONITE 



Its abundance in afragmental condition in Vanua Levu, 337. — Its occurrence in 

 deep-sea deposits, 338. — Modes of formation in situ,^ 338. — In the 

 upper portion of a basaltic flow, 339. — In the groundmass of hemi-crystal- 

 line basaltic rocks, 339. — In veins in a basic tuff-agglomerate, 340. — In the 

 fissures of a basaltic dyke, 341. — In the matrix of pitch-stone agglomerates, 

 349. — In "crush-tuffs," 341.— Regarded as a solidified magma-residuum of 

 low fusibility, 342.— Its connection with crushing, 342. — Bunsen's experi- 

 ment, 343. — Rosenbusch and Renard, 344. — The Nandua series of beds, 

 345. — Suggested explanation of the origin of palagonite, 346.— Type of 

 basalt associated with palagonite, 347. — Hydration and disintegration of 

 palagonite, 348 Pages 337—349 



CHAPTER XXV 



SILICIFIED CORALS, FLINTS, LIMONITE 



Mode of occurrence of the silicified corals, 351.— Their character and structure, 

 352.— Flints, nodules of Chalcedony, Agates, etc., 353.— Other siliceous 

 concretions, 354.— Jasper, 355.— Deposits of Limonite, 356.— Magnetic 

 Iron-sand, 357. — Suggested explanation of the silicification of the corals, 

 358,— Note on a sihcified Tree-fern, 360 Pages 350—360 



CHAPTER XXVI 



MAGNETIC ROCKS 



Previous observations, 361.— Magnetic Polarity usually caused by atmospheric 

 electricity, 362.— Displayed by both acid and basic rocks, 364.— Very 

 frequent in Vanua Levu, 365.— Its relation to specific weight, 366.— The 

 influence of locality, 367.— Frequently observed in mountain peaks, 367.— 

 Description of the peaks, 368.— Measurement of the polarity of rocks, 370. 



Pages 361—371 



