SEDIMENTATION, ENVIRONMENT, AND EVOLUTION. 25 



Much, light was thrown upon the deposits of ancient times 

 by the results of the " Challenger " Expedition in 1873-76, 

 albeit the work was confined very largely to deep-sea deposits. 

 From the geological as well as the biological, chemical, and 

 physical standpoints, the benefits which are likely to accrue 

 from a new " Challenger " Expedition, such as that suggested 

 recently by the President of the British Association for the 

 Advancement of Science,* cannot be over-estimated. Apart 

 from the storehouse of new facts in nature always ready to be 

 drawn upon, we now realise more clearly than in 1872 what 

 problems require elucidation and what fields lack exploration. 



Our knowledge, for example, of the terrigenous belt which 

 fringes the continents is inadequate, and seems to be relatively 

 less than that of the depths of the oceans. Nevertheless, most 

 of the fossiliferous strata, which it is our duty and pleasure to 

 study, were actually deposited as ancient terrigenous belts. t 

 We need more exact information regarding the exact conditions 

 of sedimentation to-day, and their influence upon plant and 

 animal life. Even the terminology of the subject cannot be 

 regarded as adequate or settled. J Few or no accurate and 

 quantitative descriptions of modern sediments exist. § 



It may therefore be an advantage if tentative suggestions 

 are here put forward regarding points upon which a new 

 " Challenger " Expedition might throw much light, and about 

 which our present knowledge is insufficient. A re-examination 



* Herdman, Professor W. A., Pres. Address, Rept. Brit. Assoc, Cardiff, 

 1920 (1921). 



f Compare for example, Professor W. W. Watts, Pres. Address, Geol. 

 Soc, 1911, p. lxXvi. 



$ For example, Professor W. A. Herdman suggested in 1895 the term 

 " neritic " to include those shallow- water, detrital deposits full of organic 

 remains, deposits which do not find a place in Murray's " Challenger " 

 scheme. 



§ In the " Challenger " reports, deposits of various-sized grains are 

 termed indiscriminately "sands" or "muds." The only quantitative 

 work which seems to have been accomplished is that by I)r. Sven Oden 

 recently on the mechanical composition of Globigerina Ooze, Radiolarian 

 Ooze, and Red Clay collected on the expedition. See Proc. Roy. Soc, 

 Edinburgh, Vol. 36 (1916), p. 219. 



