430 SYMPOSIUM ON SEDIMENTATION 



organisms living in and on tlie sediments change with their character. 

 Observations made on the Paleozoic rocks of Anticosti, Gotland, and else- 

 where have convinced me that this is one of the most fundamental factors 

 to be considered in correlation and stratigraphy. I snspect that a number 

 of our formations which are considered to bear a vertical relation to eacli 

 other or to liave been deported in distinct l)asins are laterally related to 

 each other, with the faunal differences merely due to environmental con- 

 ditions. 



The organic contents of sedimentary rocks should be studied to learn 

 if they were deported as they grew or were rolled about after death and 

 before deposition. Are the shells in natural position or are they upside 

 down? Are shells present which were broken and then healed? Infor- 

 mation of this character appears to me to be extremely valuable in the 

 interpretation of the sediments in respect to the conditions and places 

 of deposition. 



The question of paleogeography appears to me to be closely tied up 

 with the dolomite and flint problem. The "Niagaran" rocks of AViscon- 

 sin, Illinois, etcetera, are in large part at least composed of dolomite and 

 contain an abundance of flint nodules. Eocks of the same age and same 

 general conditions on the island of Anticosti, Gotland, and Esthonia con- 

 tain neither dolomite nor flint. Similarly, the Eichmond strata of Wis- 

 consin are filled with flint; yet there is none in the Eichmond deposits 

 of Anticosti or Esthonia. To interpret these differences, I think we need 

 the assistance of the paleogeographer and facts relating to paleogeography. 



E. M. Kindle : Professor Twenhofel in his remarks dwelt forcibly on 

 the inadequacy and uncertainty of meaning of the color nomenclature 

 used by geologists. I would call attention in this connection to the elab- 

 orate and exhaustive scheme of color shades and nomenclature which has 

 been worked out and used by zoologists. Mr. Eidgway's volume on this 

 subject furnishes the illustrations and nomenclature for more than one 

 thousand different shades of color. I believe that a less elaborate color 

 scheme would be adequate to the needs of most geologists and suggest 

 that a satisfactory one could be selected from Eidgway's color manual by 

 a committee of geologists. This is one of the things which should be 

 undertaken in connection with the initiation of the more precise and 

 exhaustive study of sediments now under consideration. 



Doctor Vaughan has suggested in his excellent presentation of plans 

 for researches in sedimentation the cooperation of various groups of 

 geologists. He has mentioned the universities and the State Geological 

 Surveys among the groups which should be represented in this coopera- 

 tion. There is, I think, one other group of men who should be invited 



