402 T. W. VAUGHAN RESEARCHES ON SEDIMENTATION 



physical characteristics? The answer to this question would include in- 

 formation on the chemical and mineralogic composition of the rock, the 

 sizes and the percentage of the different sizes of the particles composing 

 it, the shapes of the particles, the percentage of pore space, and the per- 

 centage of particles of different kinds. 



2. What were the sources of the constituents of the rock ? The answer 

 to this question would tell whether the constituents are clastic, organic, 

 or chemical in origin; or, if the constituents have been derived from 

 more than one source, as usually is the case in sedimentary rocks, what 

 the proportion of each kind is according to its source. In the case of 

 clastic constituents, information would be given on nature of the parent 

 rock, where it was, its topographic features and relations, and by what 

 processes it was disintegrated. In the case of constituents of organic 

 origin, the kinds of organisms, the relative importance of each kind, and 

 the relative importance of the total organic constituents would be ascer- 

 tained. In the case of chemically deposited constituents, the relative 

 importance of the different constituents and the processes by which they 

 were formed would be made known. 



3. How were the constituents brought to the place of their deposition ? 

 The answer to this question would let us know whether the transporting 

 agent was wind, flowing Avater, ice, or gravity without the help of these 

 agents, or whether two or more agents acted jointly. We should also 

 know the velocity of the transporting agents and their capacity for mov- 

 ing material. 



4. What were the factors that caused deposition; what were the agen- 

 cies that caused the particular arrangement in beds, laminae, etcetera, 

 exhibited by the deposit? Deposition may be caused by checking the 

 velocity of a transporting agent, by the flocculation of particles, or by 

 crystallization from a supersaturated solution. If this question were 

 answered, we should know not only the part played by each of these 

 processes, but should also know how currents were checked, the processes 

 involved in the flocculation of the particles, and the nature of the solu- 

 tions from which crystallization took place. Information would also be 

 given on rates of deposition. 



5. Under what conditions not necessarily factors in origin, transporta- 

 tion, and cause of deposition did deposition take place? The answer to 

 this question would comprise information on the chemical composition 

 of the water, in the case of aqueous sediments; the depth of the water; 

 the relations to land areas — distance from the land, the topographic fea- 

 tures of the land, and the climate of the land; and whether the deposit 

 was made on a stationary, rising, or sinking basement. 



