CHAPTER X. 



THE CONTINUITY OP THE CHALK. 



Points of Eesemblance 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. Palaeontological Evidence. 

 --Chalk-flints. Modern Sponges, and Yentriculites. 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. 



Frankland, F.R.S. 

 APPENDIX C. Notes on Specimens of the Bottom collected during 



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



F.R.S. 

 APPENDIX 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 submitted to chemical analysis and 



H H 2 



