26 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



of much of the geological material collected on the former 

 expedition would doubtless yield valuable results, but there 

 can be no question as to the advantage of collecting material 

 more systematically and fully (so far as terrigenous deposits 

 are concerned), and noting as far as possible the exact con- 

 ditions of accumulation. 



The following suggestions are not intended to be exhaus- 

 tive ; they are rather those which occur to one interested 

 particularly in the petrology of sediments : — 



Geological Investigations which it is Desirable that a 

 New " Challenger " Expedition Should Undertake. 



1. A more comprehensive and detailed scheme of classification 



of deposits, especially the terrigenous group. 



2. The description of all deposits, so far as possible, on a 



quantitative basis, i.e., by mechanical analyses, with 

 a terminology founded on such a basis. The full 

 determination, qualitatively and quantitatively, by 

 modern petrological methods of the mineral constituents 

 of sediments. 



3. Investigation of the methods of mechanical precipitation 



of sediments in sea- water, and the effect on size of grain 

 or aggregate of the salinity (including lime-contents, 

 etc.) and temperature (upon which the viscosity of the 

 water depends). 



4. The relation of the sediment (grain-size and general 



chemical character) to the depth of water in which 

 laid down ; the consideration of what is the deepest 

 water indicated by any particular type of sediment, as 

 bearing upon the question of permanence or instability 

 of the continents and oceans, and on the origin of certain 

 rocks. 



5. Further investigation of the effects of chemical precipita- 



tion or replacement of deposits under varying conditions 





