CHAPTER X. 
THE CONTINUITY OF THE CHALK. 
Points of Resemblance between the Atlantic Ooze and the White 
Chalk.—Differences between them.—Composition of Chalk.—The 
Doctrine of the Continuity of the Chalk.— Objections. —Arguments 
in favour of the View from Physical Geology and Geography.— 
Former Distribution of Sea and Land.—Palontological Evidence. 
—Chalk-flints—Modern Sponges, and Ventriculites.~—Corals.— 
Echinoderms.— Mollusca. —Opinions of Professor Huxley and Mr. 
Prestwich.—The Composition of Sea-water. 
Matter.—Analysis of the contained Gases.— Differences of Specific 
Gravity.—Conclusion. 
Presence of Organic 
Apprenpix A,—Summary of the Results of the Examination of Samples 
of Sea-water taken at the Surface and at various Depths. By 
William Lant Carpenter, B.A., B.Sc. 
APPENDIX B.—Results of the Analyses of Eight Samples of Sea-water 
collected during the Third Cruise of the ‘Porcupine.’ By Dr. 
Frankland, F.R.S. 
Apprenbix C.—Notes on Specimens of the Bottom collected during 
the First Cruise of the ‘Porcupine’ in 1869. By David Forbes, 
FE.R.S. 
Appenpix D.—Note on the Carbonic Acid contained in Sea-water. 
By John Young Buchanan, M.A., Chemist to the ‘Challenger’ 
Expedition. 
Very speedily after the first samples of the bottom of 
the mid-Atlantic had been brought up by the sound- 
ing-line, and submittel to chemical analysis and 
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