CHAPTER X. 



THE CONTINUITY OV THE CHALK. 



Points of Eesemlilance between tlie 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 Yiew from Physical Geology and Geography. — 

 Former Distribution of Sea and Land. — Palseontological Evidence. 

 — Chalk-flints! — Modern Sponges, and Ventriculites. — Corals. — 

 Echinoderms. — Mollusca. — Opinions of Professor Huxley and Mr. 

 Prestwich. — The Composition of Sea-water.- — Presence of Organic 

 Matter. — Analysis of the contained Gases. — Differences of Specific 

 Gravity. — Conclusion. 



Appendix 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. 



Erankland, F.R.S. 

 Appendix C. — Notes on Specimens of the Bottom collected during 



the First Cruise of the 'Porcupine' in 1869. By David Forbes, 



P.R.S. 

 Appendix D. — Note on the Carbonic Acid contained in Sea-water. 



By John Young Buchanan, M. A., Chemist to the ' Challenger ' 



Expedition. 



Veey speedily after the first samples of the bottom of 

 the mid- Atlantic had been brought np by the sound- 

 ing-line, and submitted to chemical analysis and 



H H 2 



