SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 27 



of depth, i.e., under varying pressure and temperature 

 in sea-water, and of varying content of silica, calcium, 

 magnesium, and carbon dioxide ; and on the formation 

 of dolomite,* colloidal silica (e.g., flint), etc. 



6. Precipitation through such organic agency as that of 



bacteria, as suggested in the case of limestones. t (In 

 this connexion, the present-day analogue of the Chalk 

 cannot be regarded as globigerina ooze). 



7. The relation of the character of sediments to rising and 



sinking adjacent land areas from which they are 

 derived ; the criteria in each case — mechanical, mineral, 

 and chemical ; the effect on organisms ; the composition 

 of the sea-water in each case. 



8. Further investigation of coral-reef formation. Evidence 



of upheaval or submergence provided by the relief of 

 islands and the form of the coast-line. 



9. The petro logical character and possible origin of the 



boulders on the sea-bottom — especially in the case of 

 the various " narrow " seas.f 

 10. The possibilities of deep-sea boring, by Joly's or other 

 apparatus, and the bearing of the evidence yielded on 

 Recent and Tertiary geological history and climatic 

 conditions, and on the question of the permanence of 

 the oceans. § 



* See Watts, Professor W. W.. in discussion upon Professor E. W. 

 Skeats's paper. Q.J.G.S., Vol. 61 (1905), p. 141. 



f G. H. Drew " On the Precipitation of Calcium Carbonate in the Sea 

 by Marine Bacteria, etc." Publication No. 182, Carnegie Institution, 

 Washington, 1914. 



$ See Peach, B. N., Proc. Boy. Soc., Edinburgh, Vol. 32 (1912), p. 262. 

 Cole, Professor G. A. T., and Crook, T., Mem. Geol. Surv., Ireland, " Rock- 

 Specimens dredged from the Floor of the Atlantic " (1910). Herdman, 

 Professor W. A., and Lomas, J., 7th, 8th, 9th, 12th Ann. Reports, Liverpool 

 Marine Biol. Committee, 1894-5-6 and 8. Also Proc. Liv. Geol. Soc, Vol. 8 

 (1898), p. 205. 



§ On deep-sea boring apparatus, by which it is considered that a 

 depth of several feet might be bored in the sea-floor, see Joly, Professor J., 

 Sci. Proc. Roy. Dublin Soc, New Series, Vol. 8 (1897), p. 509, and Vol. 14 

 (1914), p. 256. Also Evans, J. W., Bept. Brit. Assoc, Bournemouth, 1919 

 (1920), p. 179. 



